Patent Publication Number: US-11643556-B2

Title: Fluorescent conjugated polymers

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     Pursuant to 35 U.S.C. § 119 (e), this application claims priority to the filing date of U.S. Provisional Patent Application Ser. No. 62/359,632, filed Jul. 7, 2016, the disclosure of which application is incorporated herein by reference. 
    
    
     INTRODUCTION 
     Fluorescent dyes are compounds which, when irradiated with light of a wavelength which they absorb, emit light of a (usually) different wavelength. Fluorescent dyes find use in a variety of applications in biochemistry, biology and medicine, e.g. in diagnostic kits, in microscopy or in drug screening. Fluorescent dyes are characterized by a number of parameters allowing a user to select a suitable dye depending on the desired purpose. Parameters of interest include the excitation wavelength maximum, the emission wavelength maximum, the Stokes shift, the extinction coefficient, the fluorescence quantum yield and the fluorescence lifetime. Dyes may be selected according to the application of interest in order to, e.g., allow penetration of exciting radiation into biological samples, to minimize background fluorescence and/or to achieve a high signal-to-noise ratio. 
     Molecular recognition involves the specific binding of two molecules. Molecules which have binding specificity for a target biomolecule find use in a variety of research and diagnostic applications, such as the labeling and separation of analytes, flow cytometry, in situ hybridization, enzyme-linked immunosorbent assays (ELISAs), western blot analysis, magnetic cell separations and chromatography. Target biomolecules may be detected by labeling with a fluorescent dye. 
     SUMMARY 
     Water solvated polymeric dyes and polymeric tandem dyes are provided. The polymeric dyes include a water solvated light harvesting multichromophore having a conjugated segment of aryl or heteroaryl co-monomers linked via covalent bonds, vinylene groups or ethynylene groups. The polymeric tandem dyes further include a signaling chromophore covalently linked to the multichromophore in energy-receiving proximity therewith. Also provided are labeled specific binding members that include the subject polymeric dyes. Methods of evaluating a sample for the presence of a target analyte and methods of labeling a target molecule in which the subject polymeric dyes find use are also provided. Systems and kits for practicing the subject methods are also provided. 
    
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
       It is understood that the drawings, described below, are for illustration purposes only. The drawings are not intended to limit the scope of the present teachings in any way. 
         FIG.  1   , panels A-B, shows normalized absorption and emission spectra (panel B) for exemplary polymeric dyes and polymeric tandem dyes based on the core polymeric dye structure 1 (panel A). Red Tandem includes Dye=Dyomics dye DY-633. NIR (near IR) Tandem includes Dye=Dyomics dye DY-752. 
         FIG.  2    depicts exemplary polymeric dyes including a common 1, 4-linked phenyl co-monomer linked via ethynylene groups and a variety of M 2  co-monomers. 
         FIG.  3    depicts exemplary polymeric dyes including a common 1, 3-linked phenyl co-monomer linked via ethynylene groups and a variety of M 2  co-monomers. 
         FIG.  4    depicts exemplary polymeric dyes including a common 1, 3-linked or 1, 4-linked phenyl co-monomer linked via ethynylene groups and a variety of co-monomers and further including co-monomers having an internal linking site for attachment of a signaling chromophore (“Dye”). 
         FIG.  5    depicts exemplary water solvated polymeric dyes including co-monomers linked via ethynylene groups. 
         FIG.  6    depicts exemplary water solvated polymeric dyes including substituted phenyl co-monomers linked via vinylene groups. 
         FIG.  7    depicts exemplary water solvated polymeric dyes including substituted phenyl co-monomers linked via vinylene groups. 
     
    
    
     DEFINITIONS 
     Before describing exemplary embodiments in greater detail, the following definitions are set forth to illustrate and define the meaning and scope of the terms used in the description. 
     Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Still, certain terms are defined below for the sake of clarity and ease of reference. 
     It must be noted that as used herein and in the appended claims, the singular forms “a”, “an”, and “the” include plural referents unless the context clearly dictates otherwise. For example, the term “a primer” refers to one or more primers, i.e., a single primer and multiple primers. It is further noted that the claims can be drafted to exclude any optional element. As such, this statement is intended to serve as antecedent basis for use of such exclusive terminology as “solely,” “only” and the like in connection with the recitation of claim elements, or use of a “negative” limitation. 
     As used herein, the term “sample” relates to a material or mixture of materials, in some cases in liquid form, containing one or more analytes of interest. In some embodiments, the term as used in its broadest sense, refers to any plant, animal or bacterial material containing cells or producing cellular metabolites, such as, for example, tissue or fluid isolated from an individual (including without limitation plasma, serum, cerebrospinal fluid, lymph, tears, saliva and tissue sections) or from in vitro cell culture constituents, as well as samples from the environment. The term “sample” may also refer to a “biological sample”. As used herein, the term “a biological sample” refers to a whole organism or a subset of its tissues, cells or component parts (e.g. body fluids, including, but not limited to, blood, mucus, lymphatic fluid, synovial fluid, cerebrospinal fluid, saliva, amniotic fluid, amniotic cord blood, urine, vaginal fluid and semen). A “biological sample” can also refer to a homogenate, lysate or extract prepared from a whole organism or a subset of its tissues, cells or component parts, or a fraction or portion thereof, including but not limited to, plasma, serum, spinal fluid, lymph fluid, the external sections of the skin, respiratory, intestinal, and genitourinary tracts, tears, saliva, milk, blood cells, tumors and organs. In certain embodiments, the sample has been removed from an animal or plant. Biological samples may include cells. The term “cells” is used in its conventional sense to refer to the basic structural unit of living organisms, both eukaryotic and prokaryotic, having at least a nucleus and a cell membrane. In certain embodiments, cells include prokaryotic cells, such as from bacteria. In other embodiments, cells include eukaryotic cells, such as cells obtained from biological samples from animals, plants or fungi. 
     As used herein, the terms “support bound” and “linked to a support” are used interchangeably and refer to a moiety (e.g., a specific binding member) that is linked covalently or non-covalently to a support of interest. Covalent linking may involve the chemical reaction of two compatible functional groups (e.g., two chemoselective functional groups, an electrophile and a nucleophile, etc.) to form a covalent bond between the two moieties of interest (e.g. a support and a specific binding member). In some cases, non-covalent linking may involve specific binding between two moieties of interest (e.g., two affinity moieties such as a hapten and an antibody or a biotin moiety and a streptavidin, etc.). In certain cases, non-covalent linking may involve absorption to a substrate. 
     As used herein, the term “polypeptide” refers to a polymeric form of amino acids of any length, including peptides that range from 2-50 amino acids in length and polypeptides that are greater than 50 amino acids in length. The terms “polypeptide” and “protein” are used interchangeably herein. The term “polypeptide” includes polymers of coded and non-coded amino acids, chemically or biochemically modified or derivatized amino acids, and polypeptides having modified peptide backbones in which the conventional backbone has been replaced with non-naturally occurring or synthetic backbones. A polypeptide may be of any convenient length, e.g., 2 or more amino acids, such as 4 or more amino acids, 10 or more amino acids, 20 or more amino acids, 50 or more amino acids, 100 or more amino acids, 300 or more amino acids, such as up to 500 or 1000 or more amino acids. “Peptides” may be 2 or more amino acids, such as 4 or more amino acids, 10 or more amino acids, 20 or more amino acids, such as up to 50 amino acids. In some embodiments, peptides are between 5 and 30 amino acids in length. 
     As used herein the term “isolated,” refers to an moiety of interest that is at least 60% free, at least 75% free, at least 90% free, at least 95% free, at least 98% free, and even at least 99% free from other components with which the moiety is associated with prior to purification. 
     A “plurality” contains at least 2 members. In certain cases, a plurality may have 10 or more, such as 100 or more, 1000 or more, 10,000 or more, 100,000 or more, 10 6  or more, 10 7  or more, 10 8  or more or 10 9  or more members. 
     Numeric ranges are inclusive of the numbers defining the range. 
     As used herein, the term “specific binding” refers to the ability of a capture agent (or a first member of a specific binding pair) to preferentially bind to a particular analyte (or a second member of a specific binding pair) that is present, e.g., in a homogeneous mixture of different analytes. In some instances, a specific binding interaction will discriminate between desirable and undesirable analytes in a sample with a specificity of 10-fold or more for a desirable analyte over an undesirable analytes, such as 100-fold or more, or 1000-fold or more. In some cases, the affinity between a capture agent and analyte when they are specifically bound in a capture agent/analyte complex is at least 10 −8  M, at least 10 −9 M, such as up to 10 −10  M. 
     As used herein, the terms “affinity” and “avidity” have the same meaning and may be used interchangeably herein. “Affinity” refers to the strength of binding, increased binding affinity being correlated with a lower Kd. 
     The methods described herein include multiple steps. Each step may be performed after a predetermined amount of time has elapsed between steps, as desired. As such, the time between performing each step may be 1 second or more, 10 seconds or more, 30 seconds or more, 60 seconds or more, 5 minutes or more, 10 minutes or more, 60 minutes or more and including 5 hours or more. In certain embodiments, each subsequent step is performed immediately after completion of the previous step. In other embodiments, a step may be performed after an incubation or waiting time after completion of the previous step, e.g., a few minutes to an overnight waiting time. 
     As used herein, the terms “evaluating”, “determining,” “measuring.” and “assessing,” and “assaying” are used interchangeably and include both quantitative and qualitative determinations. 
     The term “separating”, as used herein, refers to physical separation of two elements (e.g., by size or affinity, etc.) as well as degradation of one element, leaving the other intact. 
     As used herein, the term “linker” or “linkage” refers to a linking moiety that connects two groups and has a backbone of 100 atoms or less in length. A linker or linkage may be a covalent bond that connects two groups or a chain of between 1 and 100 atoms in length, for example a chain of 1, 2, 3, 4, 5, 6, 8, 10, 12, 14, 16, 18, 20 or more carbon atoms in length, where the linker may be linear, branched, cyclic or a single atom. In some cases, the linker is a branching linker that refers to a linking moiety that connects three or more groups. In certain cases, one, two, three, four or five or more carbon atoms of a linker backbone may be optionally substituted with a sulfur, nitrogen or oxygen heteroatom. In some cases, the linker backbone includes a linking functional group, such as an ether, thioether, amino, amide, sulfonamide, carbamate, thiocarbamate, urea, thiourea, ester, thioester or imine. The bonds between backbone atoms may be saturated or unsaturated, and in some cases not more than one, two, or three unsaturated bonds are present in a linker backbone. The linker may include one or more substituent groups, for example with an alkyl, aryl or alkenyl group. A linker may include, without limitations, polyethylene glycol; ethers, thioethers, tertiary amines, alkyls, which may be straight or branched, e.g., methyl, ethyl, n-propyl, 1-methylethyl (iso-propyl), n-butyl, n-pentyl, 1,1-dimethylethyl (t-butyl), and the like. The linker backbone may include a cyclic group, for example, an aryl, a heterocycle or a cycloalkyl group, where 2 or more atoms, e.g., 2, 3 or 4 atoms, of the cyclic group are included in the backbone. A linker may be cleavable or non-cleavable. 
     As used herein, the terms “polyethylene oxide”, “PEO”, “polyethylene glycol” and “PEG” are used interchangeably and refer to a polymeric group including a chain described by the formula —(CH 2 —CH 2 —O—) n — or a derivative thereof. In some embodiments, “n” is 5000 or less, such as 1000 or less, 500 or less, 200 or less, 100 or less, 50 or less, 40 or less, 30 or less, 20 or less, 15 or less, such as 3 to 15, or 10 to 15. It is understood that the PEG polymeric group may be of any convenient length and may include a variety of terminal groups and/or further substituent groups, including but not limited to, alkyl, aryl, hydroxyl, amino, acyl, acyloxy, and amido terminal and/or substituent groups. PEG groups that may be adapted for use in the subject multichromophores include those PEGs described by S. Zalipsky in “Functionalized poly(ethylene glycol) for preparation of biologically relevant conjugates”, Bioconjugate Chemistry 1995, 6 (2), 150-165; and by Zhu et al in “Water-Soluble Conjugated Polymers for Imaging, Diagnosis, and Therapy”, Chem. Rev., 2012, 112 (8), pp 4687-4735. 
     As used herein, the term “alkyl” by itself or as part of another substituent refers to a saturated branched or straight-chain monovalent hydrocarbon radical derived by the removal of one hydrogen atom from a single carbon atom of a parent alkane. Alkyl groups of interest include, but are not limited to, methyl; ethyl, propyls such as propan-1-yl or propan-2-yl; and butyls such as butan-1-yl, butan-2-yl, 2-methyl-propan-1-yl or 2-methyl-propan-2-yl. In some embodiments, an alkyl group includes from 1 to 20 carbon atoms. In some embodiments, an alkyl group includes from 1 to 10 carbon atoms. In certain embodiments, an alkyl group includes from 1 to 6 carbon atoms, such as from 1 to 4 carbon atoms. This term includes, by way of example, linear and branched hydrocarbyl groups such as methyl (CH 3 —), ethyl (CH 3 CH 2 —), n-propyl (CH 3 CH 2 CH 2 —), isopropyl ((CH 3 ) 2 CH—), n-butyl (CH 3 CH 2 CH 2 CH 2 —), isobutyl ((CH 3 ) 2 CHCH 2 —), sec-butyl ((CH 3 )(CH 3 CH 2 )CH—), t-butyl ((CH 3 ) 3 C—), n-pentyl (CH 3 CH 2 CH 2 CH 2 CH 2 —), and neopentyl ((CH 3 ) 3 CCH 2 —). 
     The term “substituted alkyl” refers to an alkyl group as defined herein wherein one or more carbon atoms in the alkyl chain have been optionally replaced with a heteroatom such as —O—, —N—, —S—, —S(O) n — (where n is 0 to 2), —NR— (where R is hydrogen or alkyl) and having from 1 to 5 substituents selected from the group consisting of alkoxy, substituted alkoxy, cycloalkyl, substituted cycloalkyl, cycloalkenyl, substituted cycloalkenyl, acyl, acylamino, acyloxy, amino, aminoacyl, aminoacyloxy, oxyaminoacyl, azido, cyano, halogen, hydroxyl, oxo, thioketo, carboxyl, carboxylalkyl, thioaryloxy, thioheteroaryloxy, thioheterocyclooxy, thiol, thioalkoxy, substituted thioalkoxy, aryl, aryloxy, heteroaryl, heteroaryloxy, heterocyclyl, heterocyclooxy, hydroxyamino, alkoxyamino, nitro, —SO-alkyl, —SO-aryl, —SO-heteroaryl, —SO 2 -alkyl, —SO 2 -aryl, —SO 2 -heteroaryl, and —NR a R b , wherein R′ and R″ may be the same or different and are chosen from hydrogen, optionally substituted alkyl, cycloalkyl, alkenyl, cycloalkenyl, alkynyl, aryl, heteroaryl and heterocyclic. 
     “Alkoxy” refers to the group —O-alkyl, wherein alkyl is as defined herein. Alkoxy includes, by way of example, methoxy, ethoxy, n-propoxy, isopropoxy, n-butoxy, t-butoxy, sec-butoxy, n-pentoxy, and the like. The term “alkoxy” also refers to the groups alkenyl-O—, cycloalkyl-O—, cycloalkenyl-O—, and alkynyl-O—, where alkenyl, cycloalkyl, cycloalkenyl, and alkynyl are as defined herein. 
     The term “substituted alkoxy” refers to the groups substituted alkyl-O—, substituted alkenyl-O—, substituted cycloalkyl-O—, substituted cycloalkenyl-O—, and substituted alkynyl-O— where substituted alkyl, substituted alkenyl, substituted cycloalkyl, substituted cycloalkenyl and substituted alkynyl are as defined herein. 
     “Amino” refers to the group —NH 2 . 
     The term “substituted amino” refers to the group —NRR where each R is independently selected from the group consisting of hydrogen, alkyl, substituted alkyl, cycloalkyl, substituted cycloalkyl, alkenyl, substituted alkenyl, cycloalkenyl, substituted cycloalkenyl, alkynyl, substituted alkynyl, aryl, heteroaryl, and heterocyclyl provided that at least one R is not hydrogen. 
     “Aryl” by itself or as part of another substituent refers to a monovalent aromatic hydrocarbon radical derived by the removal of one hydrogen atom from a single carbon atom of an aromatic ring system. Aryl groups of interest include, but are not limited to, groups derived from aceanthrylene, acenaphthylene, acephenanthrylene, anthracene, azulene, benzene, chrysene, coronene, fluoranthene, fluorene, hexacene, hexaphene, hexalene, as-indacene, s-indacene, indane, indene, naphthalene, octacene, octaphene, octalene, ovalene, penta-2,4-diene, pentacene, pentalene, pentaphene, perylene, phenalene, phenanthrene, picene, pleiadene, pyrene, pyranthrene, rubicene, triphenylene, trinaphthalene and the like. In certain embodiments, an aryl group includes from 6 to 20 carbon atoms. In certain embodiments, an aryl group includes from 6 to 12 carbon atoms. Examples of an aryl group are phenyl and naphthyl. 
     “Heteroaryl” by itself or as part of another substituent, refers to a monovalent heteroaromatic radical derived by the removal of one hydrogen atom from a single atom of a heteroaromatic ring system. Heteroaryl groups of interest include, but are not limited to, groups derived from acridine, arsindole, carbazole, β-carboline, chromane, chromene, cinnoline, furan, imidazole, indazole, indole, indoline, indolizine, isobenzofuran, isochromene, isoindole, isoindoline, isoquinoline, isothiazole, isoxazole, naphthyridine, oxadiazole, oxazole, perimidine, phenanthridine, phenanthroline, phenazine, phthalazine, pteridine, purine, pyran, pyrazine, pyrazole, pyridazine, pyridine, pyrimidine, pyrrole, pyrrolizine, quinazoline, quinoline, quinolizine, quinoxaline, tetrazole, thiadiazole, thiazole, triazole, benzotriazole, thiophene, triazole, xanthene, benzodioxole and the like. In certain embodiments, the heteroaryl group is from 5-20 membered heteroaryl. In certain embodiments, the heteroaryl group is from 5-10 membered heteroaryl. In certain embodiments, heteroaryl groups are those derived from thiophene, pyrrole, benzothiophene, benzofuran, indole, pyridine, quinoline, imidazole, oxazole and pyrazine. 
     “Heterocycle,” “heterocyclic,” “heterocycloalkyl,” and “heterocyclyl” refer to a saturated or unsaturated group having a single ring or multiple condensed rings, including fused bridged and spiro ring systems, and having from 3 to 20 ring atoms, including 1 to 10 hetero atoms. These ring atoms are selected from the group consisting of nitrogen, sulfur, or oxygen, wherein, in fused ring systems, one or more of the rings can be cycloalkyl, aryl, or heteroaryl, provided that the point of attachment is through the non-aromatic ring. In certain embodiments, the nitrogen and/or sulfur atom(s) of the heterocyclic group are optionally oxidized to provide for the N-oxide, —S(O)—, or —SO 2 -moieties. 
     Examples of heterocycles and heteroaryls include, but are not limited to, azetidine, pyrrole, imidazole, pyrazole, pyridine, pyrazine, pyrimidine, pyridazine, indolizine, isoindole, indole, dihydroindole, indazole, purine, quinolizine, isoquinoline, quinoline, phthalazine, naphthylpyridine, quinoxaline, quinazoline, cinnoline, pteridine, carbazole, carboline, phenanthridine, acridine, phenanthroline, isothiazole, phenazine, isoxazole, phenoxazine, phenothiazine, imidazolidine, imidazoline, piperidine, piperazine, indoline, phthalimide, 1,2,3,4-tetrahydroisoquinoline, 4,5,6,7-tetrahydrobenzo[b]thiophene, thiazole, thiazolidine, thiophene, benzo[b]thiophene, morpholinyl, thiomorpholinyl (also referred to as thiamorpholinyl), 1,1-dioxothiomorpholinyl, piperidinyl, pyrrolidine, tetrahydrofuranyl, and the like. 
     Unless otherwise constrained by the definition for the heterocyclic substituent, such heterocyclic groups can be optionally substituted with 1 to 5, or from 1 to 3 substituents, selected from alkoxy, substituted alkoxy, cycloalkyl, substituted cycloalkyl, cycloalkenyl, substituted cycloalkenyl, acyl, acylamino, acyloxy, amino, substituted amino, aminoacyl, aminoacyloxy, oxyaminoacyl, azido, cyano, halogen, hydroxyl, oxo, thioketo, carboxyl, carboxylalkyl, thioaryloxy, thioheteroaryloxy, thioheterocyclooxy, thiol, thioalkoxy, substituted thioalkoxy, aryl, aryloxy, heteroaryl, heteroaryloxy, heterocyclyl, heterocyclooxy, hydroxyamino, alkoxyamino, nitro, —SO-alkyl, —SO-substituted alkyl, —SO-aryl, —SO-heteroaryl, —SO 2 -alkyl, —SO 2 -substituted alkyl, —SO 2 -aryl, —SO 2 -heteroaryl, and fused heterocycle. 
     The term “alkaryl” or “aralkyl” refers to the groups -alkylene-aryl and substituted alkylene-aryl where alkylene, substituted alkylene and aryl are defined herein. 
     “Alkylene” refers to divalent aliphatic hydrocarbyl groups preferably having from 1 to 6 and more preferably 1 to 3 carbon atoms that are either straight-chained or branched, and which are optionally interrupted with one or more groups selected from —O—, —NR 10 —, —NR 10 C(O)—, —C(O)NR 10 — and the like. This term includes, by way of example, methylene (—CH 2 —), ethylene (—CH 2 CH 2 —), n-propylene (—CH 2 CH 2 CH 2 —), iso-propylene (—CH 2 CH(CH 3 )—), (—C(CH 3 ) 2 CH 2 CH 2 —), (—C(CH 3 ) 2 CH 2 C(O)—), (—C(CH 3 ) 2 CH 2 C(O)NH—), (—CH(CH 3 )CH 2 —), and the like. “Substituted alkylene” refers to an alkylene group having from 1 to 3 hydrogens replaced with substituents as described for carbons in the definition of “substituted” below. 
     “Substituted” refers to a group in which one or more hydrogen atoms are independently replaced with the same or different substituent(s). Substituents of interest include, but are not limited to, alkylenedioxy (such as methylenedioxy), -M, —R 60 , —O − , ═O, —OR 60 , —SR 60 , —S − , ═S, —NR 60 R 61 , ═NR 60 , —CF 3 , —CN, —OCN, —SCN, —NO, —NO 2 , ═N 2 , —N 3 , —S(O) 2 O − , —S(O) 2 OH, —S(O) 2 R 60 , —OS(O) 2 O − , —OS(O) 2 R 60 , —P(O)(O − ) 2 , —P(O)(OR 60 ) (O − ), —OP(O)(OR 60 )(OR 61 ), —C(O)R 60 , C(S)R 60 , —C(O)OR 60 , —C(O)NR 60 R 61 , —C(O) − O − , —C(S) OR 60 , —NR 62 C(O)NR 60 R 61 , —NR 62 C(S)NR 60 R 61 , —NR 62 C(NR 63 )NR 60 R 61  and —C(NR 62 )NR 60 R 61  where M is halogen; R 60 , R 61 , R 62  and R 63  are independently hydrogen, alkyl, substituted alkyl, alkoxy, substituted alkoxy, cycloalkyl, substituted cycloalkyl, cycloheteroalkyl, substituted cycloheteroalkyl, aryl, substituted aryl, heteroaryl or substituted heteroaryl, or optionally R 60  and R 61  together with the nitrogen atom to which they are bonded form a cycloheteroalkyl or substituted cycloheteroalkyl ring; and R 64  and R 65  are independently hydrogen, alkyl, substituted alkyl, aryl, cycloalkyl, substituted cycloalkyl, cycloheteroalkyl, substituted cycloheteroalkyl, aryl, substituted aryl, heteroaryl or substituted heteroaryl, or optionally R 64  and R 65  together with the nitrogen atom to which they are bonded form a cycloheteroalkyl or substituted cycloheteroalkyl ring. In certain embodiments, substituents include -M, —R 60 , ═O, —OR 60 , —SR 60 , —S − , ═S, —NR 60 R 61 , ═NR 60 , —CF 3 , —CN, —OCN, —SCN, —NO, —NO 2 , ═N 2 , —N 3 , —S(O) 2 R 60 , —OS(O) 20 —, —OS(O) 2 R 60 , —P(O)(O − ) 2 , —P(O)(OR 60 )(O), —OP(O)(OR 60 )(OR 61 ), —C(O)R 60 , —C(S)R 60 , —C(O)OR 60 , —C(O)NR 60 R 61 , —C(O)O − , —NR 62 C(O)NR 60 R 61 . In certain embodiments, substituents include -M, —R 60 , ═O, —OR 60 , —SR 60 , —NR 60 R 61 , —CF 3 , —CN, —NO 2 , —S(O) 2 R 60 , —P(O)(OR 60 )(O − ), —OP(O)(OR 60 (OR 61 ), —C(O)R 60 , —C(O)OR 60 , —C(O)NR 60 R 61 , —C(O)O − . In certain embodiments, substituents include -M, —R 60 , ═O, —OR 60 , —SR 60 , —NR 60 R 61 , —CF 3 , —CN, —NO 2 , —S(O) 2 R 60 , —OP(O)(OR 60 )(OR 61 ), —C(O)R 60 , —C(O)OR 60 , —C(O)O − , where R 60 , R 61  and R 62  are as defined above. For example, a substituted group may bear a methylenedioxy substituent or one, two, or three substituents selected from a halogen atom, a (1-4C)alkyl group and a (1-4C)alkoxy group. When the group being substituted is an aryl or heteroaryl group, the substituent(s) (e.g., as described herein) may be referred to as “aryl substituent(s)”. 
     Other definitions of terms may appear throughout the specification. 
     DETAILED DESCRIPTION 
     As summarized above, water solvated polymeric dyes and polymeric tandem dyes are provided. The polymeric dyes include a water solvated light harvesting multichromophore having a conjugated segment of aryl and/or heteroaryl co-monomers linked via covalent bonds, vinylene groups or ethynylene groups. The polymeric tandem dyes further include a signaling chromophore covalently linked to the multichromophore in energy-receiving proximity therewith. Also provided are labeled specific binding members that include the subject polymeric dyes. Methods of evaluating a sample for the presence of a target analyte and methods of labeling a target molecule in which the subject polymeric dyes find use are also provided. Systems and kits for practicing the subject methods are also provided. 
     Before the various embodiments are described in greater detail, it is to be understood that the teachings of this disclosure are not limited to the particular embodiments described, and as such can, of course, vary. It is also to be understood that the terminology used herein is for the purpose of describing particular embodiments only, and is not intended to be limiting, since the scope of the present teachings will be limited only by the appended claims. 
     The section headings used herein are for organizational purposes only and are not to be construed as limiting the subject matter described in any way. While the present teachings are described in conjunction with various embodiments, it is not intended that the present teachings be limited to such embodiments. On the contrary, the present teachings encompass various alternatives, modifications, and equivalents, as will be appreciated by those of skill in the art. 
     Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs. Although any methods and materials similar or equivalent to those described herein can also be used in the practice or testing of the present teachings, some exemplary methods and materials are now described. 
     The citation of any publication is for its disclosure prior to the filing date and should not be construed as an admission that the present claims are not entitled to antedate such publication by virtue of prior invention. Further, the dates of publication provided can be different from the actual publication dates which can be independently confirmed. 
     As will be apparent to those of skill in the art upon reading this disclosure, each of the individual embodiments described and illustrated herein has discrete components and features which can be readily separated from or combined with the features of any of the other several embodiments without departing from the scope or spirit of the present teachings. Any recited method can be carried out in the order of events recited or in any other order which is logically possible. 
     All patents and publications, including all sequences disclosed within such patents and publications, referred to herein are expressly incorporated by reference. 
     In further describing the subject invention, polymeric dyes including light harvesting multichromophores and related polymeric tandem dyes further including a signaling chromophore are described first in greater detail. Next, labeled specific binding members which include the subject polymeric dyes are described. Then, methods of interest in which the subject polymeric dyes find use are reviewed. Systems and kits that may be used in practicing methods of the present disclosure are also described. 
     Polymeric Dyes 
     As summarized above, the present disclosure provides water solvated polymeric dyes. The subject water solvated polymeric dyes include a light harvesting multichromophore having a conjugated segment of aryl and/or heteroaryl co-monomers which are connected to each other via covalent bonds, vinylene groups and/or ethynylene groups. In some instances, the subject polymeric dye includes a conjugated segment of aryl and/or heteroaryl co-monomers connected via ethynylene groups. In some cases, the subject polymeric dye includes a conjugated segment of aryl and/or heteroaryl co-monomers connected via single covalent bonds. In certain instances, the subject polymeric dye includes a conjugated segment of aryl and/or heteroaryl co-monomers connected via vinylene groups. 
     As used herein, the terms “light harvesting multichromophore”, “polymeric dye” and “conjugated polymer” are used interchangeably and refer to a conjugated polymer which has a structure capable of harvesting light with a particular absorption maximum wavelength and converting it to emitted light at a longer emission maximum wavelength. In some cases, the light harvesting multichromophore is itself fluorescent. Conjugated polymers (CPs) are characterized by a delocalized electronic structure and may have an effective conjugation length that is substantially shorter than the length of the polymer chain, because the backbone may contain a large number of conjugated segments in close proximity. In some cases, conjugated polymers are efficient for light harvesting and provide for optical amplification via Forster energy transfer to an acceptor. 
     As used herein the term “unit” refers to a structural subunit of a polymer. The term unit is meant to include monomers, co-monomers, co-blocks, conjugated segments, repeating units, and the like. A “repeating unit” is a subunit of a polymer that is defined by the minimum number of distinct structural features that are required for the unit to be considered monomeric, such that when the unit is repeated n times, the resulting structure describes the polymer or a block thereof. In some cases, the polymer may include two or more different repeating units, e.g., when the polymer is a multiblock polymer or a random arrangement of units, each block may define a distinct repeating unit, e.g., an n-block and a m-block. It is understood that a variety of arrangements of n and/or m repeating units or blocks are possible and that in the depicted formula of the subject multichromophores described herein any convenient linear arrangements of n and m co-blocks of various lengths are included within the structure of the overall polymer. In some cases, a repeating unit of the polymer includes a single monomer group. In certain instances, a repeating unit of the polymer includes two or more monomer groups, i.e., co-monomer groups, such as two, three, four or more co-monomer groups. As used herein, the term “co-monomer” or “co-monomer group” refers to a structural unit of a polymer that may itself be part of a repeating unit of the polymer. In some embodiments, the conjugated polymer includes a block copolymer that is composed of blocks of polymerized monomers. In such cases, the block copolymer may be described as having distinct repeating units each corresponding to a distinct co-block of the polymer. In some cases, the polymer is a diblock copolymer that contains two different co-blocks. In such cases, the polymer may be described as including co-blocks, where each co-block may be composed of co-monomers, such as one, two, three or more co-monomers. 
     The multichromophore may have any convenient length. In some cases, the particular number of monomeric repeating units or segments of the multichromophore may fall within the range of 2 to 500,000, such as 2 to 100,000, 2 to 30,000, 2 to 10,000, 2 to 3,000 or 2 to 1,000 units or segments, or such as 5 to 100,000, 10 to 100,000, 100 to 100,000, 200 to 100,000, or 500 to 50,000 units or segments. In some instances, the particular number of monomeric repeating units or segments of the multichromophore may fall within the range of 2 to 1,000, such as 2 to 500, 2 to 100, 3 to 100, 4 to 100, 5 to 100, 6 to 100, 7 to 100, 8 to 100, 9 to 100 or 10 to 100 units or segments. 
     The multichromophore may be of any convenient molecular weight (MW). In some cases, the MW of the multichromophore may be expressed as an average molecular weight. In some instances, the polymeric dye has an average molecular weight in the range of 500 to 500,000, such as from 1,000 to 100,000, from 2,000 to 100,000, from 10,000 to 100,000 or even an average molecular weight in the range of 50,000 to 100,000. 
     In some embodiments, the multichromophore includes a particular aryl or heteroaryl co-monomer that constitutes 5% or more by molarity (e.g., 5 mol %) of the multichromophore, such as 10% or more, 15% or more, 20% or more, 25% or more, 30% or more, 40% or more, 45% or more, 50% or more, 60% or more, 70% or more, or even more by molarity of the multichromophore. In such cases, the multichromophore may include 5 or more repeating units, such as 10 or more, 20 or more, 30 or more, 40 or more, 50 or more, 60 or more, 70 or more, 80 or more, 90 or more, 100 or more, 200 or more, 500 or more, 1000 or more, 10,000 or more, or even more repeating units. In such cases, the multichromophore may include 5 or more co-monomer units, such as 10 or more, 20 or more, 30 or more, 40 or more, 50 or more, 60 or more, 70 or more, 80 or more, 90 or more, 100 or more, 200 or more, 500 or more, 1000 or more, 10,000 or more, or even more co-monomer units. In certain embodiments, the aryl or heteroaryl co-monomer of interest constitutes 25% or more by molarity of the multichromophore, such as 30% or more, 40% or more, 45% or more, 50% or more, or even more by molarity of the multichromophore, which includes 5 or more repeating units, such as 10 or more, 20 or more, 30 or more, 40 or more, 50 or more, 60 or more, 70 or more, 80 or more, 90 or more, 100 or more repeating units. 
     In some embodiments, the multichromophore includes a plurality of first optically active units forming a conjugated system, having an absorption wavelength (e.g., as described herein) at which the first optically active units absorb light to form an excited state. In certain instances, the multichromophore includes a conjugated polymer segment or an oligomeric structure including bandgap-lowering n-conjugated repeating units. 
     The subject multichromophore may have one or more desirable spectroscopic properties, such as a particular absorption maximum wavelength, a particular emission maximum wavelength, extinction coefficient, quantum yield, and the like. The subject polymeric dyes and polymeric tandem dyes provide for a variety of absorption and emission profiles which depend on a variety of factors such as the selected co-monomers, linking groups, substituents and optional linked signaling chromophores of which the polymers are composed. In some cases, the polymeric dye absorption maximum wavelength in the range of 300 to 600 nm, such as 350 nm to 560 nm or 400 nm to 560 nm. In certain embodiments, the multichromophore has an absorption maximum wavelength of 600 nm or less, such as 575 nm or less, 550 nm or less, 525 nm or less, 500 nm or less, 475 nm or less, 450 nm or less, 440 nm or less, 430 nm or less, 420 nm or less, 410 nm or less, 400 nm or less, or even less. In certain embodiments, the multichromophore absorbs only UV light. In certain instances, the multichromophore has an absorption maximum wavelength in the range of 300 nm to 400 nm. In certain instances, the multichromophore has an absorption maximum wavelength in the range of 300 nm to 350 nm. In certain instances, the multichromophore has an absorption maximum wavelength in the range of 350 nm to 400 nm. In certain instances, the multichromophore has an absorption maximum wavelength in the range of 400 nm to 600 nm, such as 400 nm to 560 nm. In certain instances, the multichromophore has an absorption maximum wavelength in the range of 400 nm to 450 nm. In certain instances, the multichromophore has an absorption maximum wavelength in the range of 450 nm to 500 nm. In certain instances, the multichromophore has an absorption maximum wavelength in the range of 500 nm to 550 nm. In certain instances, the multichromophore has an absorption maximum wavelength in the range of 550 nm to 600 nm. 
     In some embodiments, the multichromophore has an emission maximum wavelength in the range of 300 to 900 nm, such as 350 to 850 nm, 350 to 600 nm, 360 to 500 nm, 370 to 500 nm, 380 to 500 nm, 390 to 500 nm or 400 to 500 nm, where specific examples of emission maxima of interest include, but are not limited to: 395 nm±5 nm, 460 nm±5 nm, 490 nm±5 nm, 550 nm±5 nm, 560 nm±5 nm, 605 nm±5 nm, 650 nm±5 nm, 680 nm±5 nm, 700 nm±5 nm, 805 nm±5 nm. In certain instances, the multichromophore has an emission maximum wavelength selected from the group consisting of 395 nm, 460 nm, 490 nm, 550 nm, 560 nm, 605 nm, 650 nm, 680 nm, 700 nm and 805 nm. In certain instances, the multichromophore has an emission maximum wavelength of 395 nm±5 nm. In some instances, the multichromophore itself has an emission maximum wavelength in the range of 375 to 900 nm (such as in the range of 380 nm to 900 nm, 390 nm to 900 nm, or 400 nm to 900 nm). 
     In some instances, the multichromophore has an extinction coefficient of 5×10 5  cm −1 M −1  or more, such as 6×10 5  cm −1 M −1  or more, 7×10 5  cm −1 M −1  or more, 8×10 5  cm −1 M −1  or more, 9×10 5  cm −1 M −1  or more, such as 1×10 6  cm −1 M −1  or more, 1.5×10 6  cm −1 M −1  or more, 2×10 6  cm −1 M −1  or more, 2.5×10 6  cm −1 M −1  or more, 3×10 6  cm −1 M −1  or more, 4×10 6  cm −1 M −1  or more, 5×10 6  cm −1 M −1  or more, 6×10 6  cm −1 M −1  or more, 7×10 6  cm −1 M −1  or more, or 8×10 6  cm −1 M −1  or more. In such cases, the multichromophore may have 5 or more repeating units, such as 6 or more, 7 or more, 8 or more, 9 or more, 10 or more, or even more repeating units. In some embodiments, the multichromophore has a molar extinction coefficient of 5×10 5  M −1  cm −1  or more. In certain embodiments, the multichromophore has a molar extinction coefficient of 1×10 6  M −1  cm −1  or more. 
     In some instances, the multichromophore has an extinction coefficient of 40,000 cm −1 M −1  per repeating unit or more, such as 45,000 cm −1 M −1  per repeating unit or more, 50,000 cm −1 M −1  per repeating unit or more, 55,000 cm −1 M −1  per repeating unit or more, 60,000 cm −1 M −1  per repeating unit or more, 70,000 cm −1 M −1  per repeating unit or more, 80,000 cm −1 M −1  per repeating unit or more, 90,000 cm −1 M −1  per repeating unit or more, 100,000 cm −1 M −1  per repeating unit or more, or even more. In some instances, the 40,000 cm −1 M −1  per repeating unit or more described herein is an average extinction coefficient. In certain instances, the repeat unit of the multichromophore may include a single monomer, two co-monomers, or three or more co-monomers. In some instances, the multichromophore has an extinction coefficient of 40,000 cm −1 M −1  per co-monomer or more, such as 45,000 cm −1 M −1  per co-monomer or more, 50,000 cm −1 M −1  per co-monomer or more, 55,000 cm −1 M −1  per co-monomer or more, 60,000 cm −1 M −1  per co-monomer or more, 70,000 cm −1 M −1  per co-monomer or more, 80,000 cm −1 M −1  per co-monomer or more, 90,000 cm −1 M −1  per co-monomer or more, 100,000 cm −1 M −1  per co-monomer or more, or even more. In some instances, the 40,000 cm −1 M −1  per co-monomer or more is an average extinction coefficient. 
     It is understood that in some cases the subject multichromophores may include co-blocks (e.g., n and m co-blocks) or a random arrangement of n and m repeating units. The subject multichromophores may include any convenient linear arrangements of n and m co-blocks of various lengths within the structure of the overall polymer. In addition, the multichromophores may include any convenient arrangements of co-monomers within such n and/or m co-blocks. Unless indicated to the contrary, all possible arrangements of co-monomers are meant to be included in the polymeric dyes described herein. A variety of polymer synthesis methods may be utilized to prepare co-monomers and co-blocks of interest in the preparation of the subject multichromophores. It is understood that in some cases, the polymerization methods may produce a composition including a population of conjugated polymers that includes some variation with respect to the particular length and/or terminal groups (i.e., end groups) present in each conjugated polymer of the population. The formulae depicted herein may refer to a single compound or to a population or sub-population of polymeric compounds. As used herein, * denotes a site for covalent attachment to the unsaturated backbone of a conjugated polymer. 
     In some instances, the multichromophore includes a conjugated segment having the structure of formula (I): 
                         
where:
 
     each L is independently a covalent bond, a vinylene group or an ethynylene group; 
     M 1  and M 2  are independently an aryl co-monomer or a heteroaryl co-monomer; 
     each * is a site for covalent attachment to the unsaturated backbone of a conjugated polymer; and 
     n is an integer from 1 to 100,000. 
     In some instances of formula (I), each L is a covalent bond. In some instances of formula (I), each L is a vinylene group. In some cases of formula (I), each L is an ethynylene group. In certain embodiments of formula (I), M 1  and M 2  are the same aryl or heteroaryl co-monomer. In certain embodiments of formula (I), M 1  and M 2  are different aryl or heteroaryl co-monomers. In some cases of formula (I), each M 1  is a substituted phenyl co-monomer. 
     Ethynylene-Linked Polymeric Dyes 
     Aspects of the present disclosure include polymeric dyes having a conjugated segment of aryl and/or heteroaryl co-monomers connected via ethynylene groups. An ethynylene group refers to a divalent —CC— group capable of linking co-monomers of a conjugated polymer backbone. In certain instances of formula (I), the conjugated segment has the structure of formula (II): 
                         
wherein:
 
     each W is independently selected from H, an alkyl, a substituted alkyl, an aralkyl, a substituted aralkyl, an aryl, a substituted aryl, a heteroaryl, a substituted heteraryl, a PEG or modified PEG group and a water soluble group (WSG); and 
     q is 1, 2, 3 or 4. In some instances of formula (II), q is 1. In some embodiments of formula (II), q is 2. In some embodiments of formula (II), q is 3. In certain instances of formula (II), each W is a water soluble group. In certain instances of formula (II), each W is a PEG or a modified PEG group. In some instances of formula (II), each W is a substituted aralkyl (e.g., as described herein). 
     In some embodiments of formula (II), the conjugated segment has the structure of formula (III): 
     
       
         
         
             
             
         
       
     
     In some embodiments of formula (II), the conjugated segment has the structure of formula (IV): 
     
       
         
         
             
             
         
       
     
     In some instances of formulae (III)-(IV), q is 1. In some embodiments of formula (III)-(IV), q is 2. In some embodiments of formula (III)-(IV), q is 3. In certain instances of formulae (II)-(IV), each W is a water soluble group. In certain instances of formulae (II)-(IV), each W is a PEG or a modified PEG group. In some instances of formulae (II)-(IV), each W is a substituted aralkyl (e.g., as described herein). 
     In certain instances of formulae (I)-(IV), M 2  is substituted with one or more W substituents each independently selected from an alkyl, a substituted alkyl, an aralkyl, a substituted aralkyl, an aryl, a substituted aryl, a heteroaryl, a substituted heteraryl, a PEG or modified PEG group and a WSG. In certain instances of formulae (II)-(IV), M 2  is substituted with one or more W substituents that is a water soluble group. In certain instances of formulae (II)-(IV), M 2  is substituted with one or more W groups that are selected from a PEG or a modified PEG group. In some instances of formulae (II)-(IV), M 2  is substituted with one or more W substituents that is a substituted aralkyl (e.g., as described herein). In certain instances of formulae (I)-(IV), q is 2 or 3; and each W is independently selected from: —Y 1 —(CH 2 CH 2 O) r —R′; 
     —Y 1 —O—CH[(CH 2 ) q —O—(CH 2 CH 2 O) r —R′] 2 ; and 
     —Y 1 —CH 2 -Ph(Y 1 —(CH 2 CH 2 O) r —R) s ; 
     wherein Y 1  is selected from a covalent bond, —O—, —CONH—, —NHCO— and —(CH 2 ) q —O—, q and r are each independently an integer from 1 to 50, s is 1, 2 or 3 and each R′ is independently H, alkyl (e.g., methyl) or substituted alkyl. 
     In some embodiments of formulae (I)-(IV), n is 5 or more, such as 10 or more, 30 or more, 100 or more, 300 or more, 1000 or more, 3000 or more, or even more. It is understood that a population of conjugated polymers may be represented by the subject formulae that includes some variation with respect to the particular length. In some cases, the conjugated segment can constitute 25 mol % or more of the multichromophore, such as 30 mol % or more, 40 mol % or more, 50 mol % or more, 60 mol % or more, 70 mol % or more, 80 mol % or more, or 90 mol % or more. 
     In some embodiments of formula (I), the multichromophore has the structure of formula (V): 
                         
wherein:
 
     M 1 , M 2 , M 3  and M 4  are independently an aryl co-monomer or heteroaryl co-monomer; 
     at least two L are an ethynylene linking units; 
     each n is independently an integer from 1 to 10,000; 
     each m is independently 0 or an integer from 1 to 10,000; 
     p is an integer from 1 to 100,000; and 
     G 1  and G 2  are each independently selected from a terminal group, a t conjugated segment, a linker and a linked specific binding member. In certain cases, each L is an ethynylene linking unit. Any convenient co-monomers can be adapted to include a sidechain substituent group that provides for conjugation of the polymeric dye to a moiety of interest, such as an signaling chromophore or a biomolecule. In some instances of formula (V), co-monomer M 3  or M 4  includes such a sidechain substituent group. Any of the co-monomers can include a substituent that imparts increased water solubility upon the polymeric dye. 
     In some embodiments of any of the formulae described herein, n, m and p are selected such that the multichromophore includes 2 to 100,000 repeat units (i.e., monomeric repeat units) in total, where the multichromophore may include a variety of distinct monomeric repeat units. In some instances, when m is 0, p is 1 and n is 2 to 100,000. It is understood that the conjugated polymer of formulae described herein can also be represented by a formula that provides mol % values for each co-monomer in the polymer. It is further understood that in some cases, the polymerization methods may produce a composition including a population of conjugated polymers that includes some variation with respect to the particular length and/or terminal groups (i.e., end groups) present in each conjugated polymer of the population. The formulae depicted herein may refer to a single compound or to a population or sub-population of polymeric compounds. 
     In certain instances of formula (V), the multichromophore has the structure of formula (VI): 
                         
wherein n is an integer from 1 to 100,000.
 
     In certain instances of formula (V), the multichromophore has the structure of formula (VII): 
                         
wherein: Z 1  is a chemoselective functional group or a linked signaling chromophore; and T 1  is a linker. In some cases, Z 1  is a chemoselective functional group that can be utilized to conjugate a molecule of interest to the polymeric dye. In certain cases, Z 1  is a linked signaling chromophore.
 
     In certain embodiments of formula (V), the multichromophore has the structure of formula (VIII): 
                         
wherein: Z 1  is a chemoselective functional group or a linked signaling chromophore; and T 1  is a linker. In some cases, Z 1  is a chemoselective functional group that can be utilized to conjugate a molecule of interest to the polymeric dye. In certain cases, Z 1  is a linked signaling chromophore. In some instances of formulae (V)-(VIII), M 1  and M 3  are the same aryl or heteroaryl co-monomer.
 
     In some cases of formulae (V)-(VIII), each M 1  is a substituted phenyl co-monomer, such as a substituted 1,4-phenyl co-monomer or a substituted 1,3-phenyl co-monomer. In some cases of formulae (V)-(VIII), the multichromophore includes a conjugated segment structure of formula (III): 
     
       
         
         
             
             
         
       
     
     wherein: each W is independently selected from H, an alkyl, a substituted alkyl, an aralkyl, a substituted aralkyl, an aryl, a substituted aryl, a heteroaryl, a substituted heteroaryl, a PEG or modified PEG group and a WSG; and q is 1, 2, 3 or 4. In some embodiments of formula (III), q is 1. In some embodiments of formula (III), q is 2. In certain instances of formula (III), each W is a water soluble group. In certain instances of formula (III), each W is a PEG or a modified PEG group. In some instances of formula (III), each W is a substituted aralkyl (e.g., as described herein). 
     In some cases of formulae (V)-(VIII), the multichromophore includes the conjugated segment structure of formula (IV): 
                         
wherein: each W is independently selected from H, an alkyl, a substituted alkyl, an aralkyl, a substituted aralkyl, an aryl, a substituted aryl, a heteroaryl, a substituted heteraryl, a PEG or modified PEG group and a WSG; and q is 1, 2, 3 or 4. In some embodiments of formula (IV), q is 1. In some embodiments of formula (IV), q is 2. In certain instances of formula (IV), each W is a water soluble group. In certain instances of formula (IV), each W is a PEG or a modified PEG group. In some instances of formula (IV), each W is a substituted aralkyl (e.g., as described herein).
 
     In some embodiments of formula (V), the multichromophore has the structure of formula (IX): 
                         
wherein: each W is independently selected from H, an alkyl, a substituted alkyl, an aralkyl, a substituted aralkyl, an aryl, a substituted aryl, a heteroaryl, a substituted heteraryl, a PEG or modified PEG group and a WSG; and q is 1, 2, 3 or 4. In some embodiments of formula (IX), q is 1. In some embodiments of formula (IX), q is 2. In certain instances of formula (IX), each W is a water soluble group. In certain instances of formula (IX), each W is a PEG or a modified PEG group. In some instances of formula (IX), each W is a substituted aralkyl (e.g., as described herein).
 
     In some embodiments of formula (IX), the phenyl co-monomers (M 1  and M 3 ) are each 1,4-linked to the conjugated polymer backbone. In certain embodiments of formula (IX), the multichromophore has the structure of formula (X): 
                         
wherein: W 1  and W 2  are as defined for W; Z 2  is a chemoselective functional group or a linked specific binding member; and T 2  is a linker. In certain instances of formula (X), Z 2  is a chemoselective functional group. In some instances of formula (X), Z 2  is a linked specific binding member. In certain instances of formula (X), W 1  and W 2  are independently a water soluble group. In certain instances of formula (X), W 1  and W 2  are independently a PEG or a modified PEG group. In some instances of formula (X), W 1  and W 2  are independently a substituted aralkyl (e.g., as described herein).
 
     In some instances of formulae (VII) and (IX), the multichromophore has the structure of formula (XI): 
                         
wherein: W 1  and W 2  are as defined for W, Z 1  is a chemoselective functional group or a linked signaling chromophore; and T 1  is a linker. In certain instances of formula (XI), W 1 , W 2  and W 3  are independently a water soluble group. In certain instances of formula (XI), W 1 , W 2  and W 3  are independently a PEG or a modified PEG group. In some instances of formula (XI), W 1 , W 2  and W 3  are independently a substituted aralkyl (e.g., as described herein). In some cases, Z 1  is a chemoselective functional group that can be utilized to conjugate a molecule of interest to the polymeric dye. In certain cases, Z 1  is a linked signaling chromophore.
 
     In certain cases, the multichromophore comprises the structure of formula (XII): 
                         
wherein: W 1 -W 3  are as defined for W; Z 2  is a chemoselective functional group or a linked specific binding member; T 2  and T 3  are each independently a linker; and Dye is a signaling chromophore. In some instances of formula (XII), Z 2  is a chemoselective functional group. In some instances of formula (XII), Z 2  is a linked specific binding member. In certain instances of formula (XII), W 1 , W 2  and W 3  are independently a water soluble group. In certain instances of formula (XII), W 1 , W 2  and W 3  are independently a PEG or a modified PEG group. In some instances of formula (XII), W 1 , W 2  and W 3  are independently a substituted aralkyl (e.g., as described herein).
 
     In some embodiments of formula (IX), the phenyl co-monomers (M 1  and M 3 ) are each 1,3-linked to the conjugated polymer backbone. In certain instances of formula (IX), the multichromophore has the structure of formula (XIII): 
                         
wherein: W 3 , W 4  and W 5  are as defined for W. In certain instances of formula (XIII), W 3 , W 4  and W 5  are independently H or a water soluble group. In certain instances of formula (XIII), W 4 , W 5  and W 6  are independently H, a PEG or a modified PEG group. In some instances of formula (XIII), W 4 , W 5  and W 6  are independently H or a substituted aralkyl (e.g., as described herein).
 
     In some embodiments of formula (IX) or (XIII), the multichromophore has the structure of formula (XIV): 
                         
wherein: W 3  and W 5  are as defined for W; Z 2  is a chemoselective functional group or a linked specific binding member; and T 2  is a linker. In certain instances of formula (XIV), Z 2  is a chemoselective functional group. In some instances of formula (XIV), Z 2  is a linked specific binding member. In certain instances of formula (XIV), W 3  and W 5  are independently a water soluble group. In certain instances of formula (XIV), W 3  and W 5  are independently a PEG or a modified PEG group. In some instances of formula (XIV), W 3  and W 5  are independently a substituted aralkyl (e.g., as described herein).
 
     In some embodiments of formula (IX), the multichromophore has the structure of formula (XV): 
                         
wherein: W 3 , W 4  and W 5  are as defined for W: Z 1  is a chemoselective functional group or a linked signaling chromophore; and T 1  is a linker. In certain instances of formula (XV), W 3 , W 4  and W 5  are independently H or a water soluble group. In certain instances of formula (XV), W 4 , W 5  and W 6  are independently H, a PEG or a modified PEG group. In some instances of formula (XV), W 4 , W 5  and W 6  are independently H or a substituted aralkyl (e.g., as described herein). In some cases, Z 1  is a chemoselective functional group that can be utilized to conjugate a molecule of interest to the polymeric dye. In certain cases, Z 1  is a linked signaling chromophore.
 
     In certain cases of formula (XV), the conjugated segment has the structure of formula (XVI): 
                         
wherein W 6  is as defined for W; Z 2  is a chemoselective functional group or a linked specific binding member; T 2  and T 3  are each independently a linker; and Dye is a signaling chromophore. In some instances of formula (XVI), Z 2  is a chemoselective functional group. In some instances of formula (XVI), Z 2  is a linked specific binding member. In certain instances of formula (XVI), W 3 , W 5  and W 6  are independently H or a water soluble group. In certain instances of formula (XVI), W 3 , W 5  and W 6  are independently H, a PEG or a modified PEG group. In some instances of formula (XVI), W 3 , W 5  and W 6  are independently H or a substituted aralkyl (e.g., as described herein).
 
     Vinylene-Linked Polymeric Dyes 
     Aspects of the present disclosure include polymeric dyes having a conjugated segment of aryl and/or heteroaryl co-monomers connected via vinylene groups. As used herein, a vinylene group refers to a divalent —CH═CH— group capable of linking two co-monomers in a conjugated polymer backbone. In certain instances, the vinyl linking group has an E-stereochemistry with respect to the adjacent linked co-monomers. In certain instances, each vinyl linking group has an E-stereochemistry configuration. In certain instances, one or more of the vinyl linking group has a Z-stereochemistry with respect to the adjacent linked co-monomers. In some embodiments of formula (I), the multichromophore has the structure of formula (V): 
                         
wherein:
 
     M 1 , M 2 , M 3  and M 4  are independently an aryl or heteroaryl co-monomer; 
     at least two L are vinylene groups; 
     each n is independently an integer from 1 to 10,000; 
     each m is 0 or independently an integer from 1 to 10,000; 
     p is an integer from 1 to 100,000; and 
     G 1  and G 2  are each independently selected from a terminal group, a t conjugated segment, a linker and a linked specific binding member. In certain cases, each L is a vinylene linking unit. Any one of the co-monomers can include a sidechain substituent group that provides for conjugation of the polymeric dye to a moiety of interest, such as a signaling chromophore or a biomolecule. Any of the co-monomers can include a substituent that imparts increased water solubility upon the polymeric dye. 
     In certain instances of formula (V), the multichromophore has the structure of formula (VII): 
                         
wherein: Z 1  is a chemoselective functional group or a linked signaling chromophore; and T 1  is a linker. In some instances, at least two L are vinylene linking units. In certain cases, each L is a vinylene linking unit. In some cases, Z 1  is a chemoselective functional group that can be utilized to conjugate a molecule of interest to the polymeric dye. In certain embodiments, Z 1  is a linked signaling chromophore.
 
     In some embodiments of formula (V) or (VII), the multichromophore includes a conjugated segment structure of formula (XVII): 
     
       
         
         
             
             
         
       
     
     wherein: each W is independently selected from H, an alkyl, a substituted alkyl, an aralkyl, a substituted aralkyl, an aryl, a substituted aryl, a heteroaryl, a substituted heteroaryl, a PEG or modified PEG group and a WSG; and q is 1, 2, 3 or 4. In some embodiments of formula (XVII), q is 1. In some embodiments of formula (XVII), q is 2. In certain instances of formula (XVII), each W is a water soluble group. In certain instances of formula (XVII), each W is a PEG or a modified PEG group. In some instances of formula (XVII), each W is a substituted aralkyl (e.g., as described herein). 
     In some embodiments of formula (XVII), the conjugated segment includes the structure of formula (XVIII): 
                         
wherein: each W is independently selected from H, an alkyl, a substituted alkyl, an aralkyl, a substituted aralkyl, an aryl, a substituted aryl, a heteroaryl, a substituted heteroaryl, a PEG or modified PEG group and a WSG; and each q is independently 1, 2, 3 or 4. In some embodiments of formula (XVII), each q is 1. In some embodiments of formula (XVII), each q is 2. In certain instances of formula (XVII), each W is a water soluble group. In certain instances of formula (XVII), each W is a PEG or a modified PEG group. In some instances of formula (XVII), each W is a substituted aralkyl (e.g., as described herein).
 
     In some embodiments of formula (XVIII), the conjugated segment includes the structure of formula (XIX) or (XX): 
                         
wherein W 7 -W 10  are as defined for W. In certain instances of formulae (XIX)-(XX), W 7 —W 10  are independently a water soluble group. In certain instances of formulae (XIX)-(XX), W 7 -W 10  are independently a PEG or a modified PEG group. In some instances of formulae (XIX)-(XX), W 7 -W 10  are independently a substituted aralkyl (e.g., as described herein).
 
     Single Covalent Bond Linked Polymeric Dyes 
     Aspects of the present disclosure include polymeric dyes having a conjugated segment of aryl and/or heteroaryl co-monomers connected via covalent bonds (e.g., a single covalent bond linking co-monomers which form a conjugated polymer backbone). In some embodiments of formula (I), the multichromophore has the structure of formula (V): 
                         
wherein:
 
     M 1 , M 2 , M 3  and M 4  are independently an aryl or heteroaryl co-monomer; 
     at least two L are covalent bonds; 
     each n is independently an integer from 1 to 10,000; 
     each m is 0 or independently an integer from 1 to 10,000; 
     p is an integer from 1 to 100,000; and 
     G 1  and G 2  are each independently selected from a terminal group, a t conjugated segment, a linker and a linked specific binding member. In certain cases, each L is a covalent bond. Any one of the co-monomers can include a sidechain substituent group that provides for conjugation of the polymeric dye to a moiety of interest, such as a signaling chromophore or a biomolecule. Any of the co-monomers can include a substituent that imparts increased water solubility upon the polymeric dye. 
     In some embodiments of formula (V), the multichromophore has the structure of formula (VII): 
                         
wherein: Z 1  is a chemoselective functional group or a linked signaling chromophore; and T 1  is a linker. In some cases, Z 1  is a chemoselective functional group that can be utilized to conjugate a molecule of interest to the polymeric dye. In certain cases, Z 1  is a linked signaling chromophore.
 
     In certain instances of formulae (V) and (VII), the multichromophore includes a conjugated segment structure of formula (XXI): 
                         
wherein W 11  and W 12  are as defined for W. In certain instances of formula (XXI), W 11  and W 12  are independently a water soluble group. In certain instances of formula (XXI), W 11  and W 12  are independently a PEG or a modified PEG group. In some instances of formula (XXI), W 11  and W 12  are independently a substituted aralkyl (e.g., as described herein).
 
     In certain instances of formulae (V) and (VII), the multichromophore includes a conjugated segment structure of formula (XXII): 
                         
wherein W 11 -W 13  are as defined for W. In certain instances of formula (XXII), W 11 -W 13  are independently a water soluble group. In certain instances of formula (XXII), W 11 -W 13  are independently a PEG or a modified PEG group. In some instances of formula (XXII), W 11 -W 13  are independently a substituted aralkyl (e.g., as described herein).
 
     Water Solubilizing Substituents 
     The subject polymeric dyes may be water solvated. Any convenient water solubilizing groups (WSG&#39;s) may be included in the multichromophores described herein (e.g., multichromophores of formulae (I)-(XXII)) to provide for increased water-solubility. While the increase in solubility may vary, in some instances the increase (as compared to the compound without the WSG(s)) is 2 fold or more, e.g., 5 fold, 10 fold, 25 fold, 50 fold, 100 fold or more. As used herein, the terms “water solubilizing group”, “water soluble group” and WSG are used interchangeably and refer to a group or substituent that is well solvated in aqueous environments e.g., under physiological conditions, and that imparts improved water solubility upon the molecules to which it is attached. In some embodiments, a WSG increases the solubility of the multichromophore in a predominantly aqueous solution, as compared to a control multichromophore which lacks the WSG. In some instances, the WSGs of the multichromophore are non-ionic side groups capable of imparting solubility in water in excess of 10 mg/mL. The water solubilizing groups may be any convenient hydrophilic group that is well solvated in aqueous environments. In some cases, the hydrophilic water solubilizing group is charged, e.g., positively or negatively charged. In certain cases, the hydrophilic water solubilizing group is a neutral hydrophilic group. In some embodiments, the WSG is a hydrophilic polymer, e.g., a polyethylene glycol, a modified PEG, a peptide sequence, a peptoid, a carbohydrate, an oxazoline, a polyol, a dendron, a dendritic polyglycerol, a cellulose, a chitosan, or a derivative thereof. Water solubilizing groups of interest include, but are not limited to, carboxylate, phosphonate, phosphate, sulfonate, sulfate, sulfinate, sulfonium, ester, polyethylene glycols (PEG) and modified PEGs, hydroxyl, amine, amino acid, ammonium, guanidinium, pyridinium, polyamine and sulfonium, polyalcohols, straight chain or cyclic saccharides, primary, secondary, tertiary, or quaternary amines and polyamines, phosphonate groups, phosphinate groups, ascorbate groups, glycols, including, polyethers, —COOM′, —SO 3 M′, —PO 3 M′, —NR 3   + , Y′, (CH 2 CH 2 O) p R and mixtures thereof, where Y′ can be any halogen, sulfate, sulfonate, or oxygen containing anion, p can be 1 to 500, each R can be independently H or an alkyl (such as methyl) and M′ can be a cationic counterion or hydrogen, —(CH 2 CH 2 O) yy CH 2 CH 2 XR yy , —(CH 2 CH 2 O) yy CH 2 CH 2 X—, —X(CH 2 CH 2 O) yy CH 2 CH 2 —, glycol, and polyethylene glycol, wherein yy is selected from 1 to 1000, X is selected from 0, S, and NR ZZ , and R ZZ  and R YY  are independently selected from H and C 1-3  alkyl. In some cases, a WSG is (CH 2 ) x (OCH 2 CH 2 ) y OCH 3  where each x is independently an integer from 0-20, each y is independently an integer from 0 to 50. In some cases, the water solubilizing group includes a non-ionic polymer (e.g., a PEG polymer) substituted at the terminal with an ionic group (e.g., a sulfonate). 
     In some embodiments of formulae, the co-monomer includes a substituent selected from (CH 2 ) x (OCH 2 CH 2 ) y OCH 3  where each x is independently an integer from 0-20, each y is independently an integer from 0 to 50; and a benzyl optionally substituted with one or more halogen, hydroxyl, C 1 -C 12  alkoxy, or (OCH 2 CH 2 ) z OCH 3  where each z is independently an integer from 0 to 50. In some instances, the substituent is (CH 2 ) 3 (OCH 2 CH 2 ) 11 OCH 3 . In some embodiments, one or more of the substituents is a benzyl substituted with at least one WSG groups (e.g., one or two WSG groups) selected from (CH 2 ) x (OCH 2 CH 2 ) y OCH 3  where each x is independently an integer from 0-20 and each y is independently an integer from 0 to 50. 
     Multiple WSGs may be included at a single location in the subject multichromophores via a branching linker. In certain embodiments, the branching linker is an aralkyl substituent, further di-substituted with water solubilizing groups. As such, in some cases, the branching linker group is a substituent of the multichromophore that connects the multichromophore to two or more water solubilizing groups. In certain embodiments, the branching linker is an amino acid, e.g., a lysine amino acid that is connected to three groups via the amino and carboxylic acid groups. In some cases, the incorporation of multiple WSGs via branching linkers imparts a desirable solubility on the multichromophore. In some instances, the WSG is a non-ionic sidechain group capable of imparting solubility in water in excess of 10 mg/mL. 
     In some embodiments, the multichromophore includes substituent(s) selected from the group consisting of, an alkyl, an aralkyl and a heterocyclic group, each group further substituted with a include water solubilizing groups hydrophilic polymer group, such as a polyethylglycol (PEG) (e.g., a PEG group of 2-20 units) or. 
     In certain instances of any one of formula (I)-(XXII), one or more of the co-monomers may be substituted with a group (e.g., each W and each W 1 -W 13  substituent group of the depicted formulae) that is independently selected from one of the following structures: 
                                           
wherein: T 5  is an optional linker; and each s is an integer from 1 to 50. In certain instances, each s is independently 1 to 20, such as 3 to 20, 3 to 15, 3 to 12, or 6 to 12. In certain cases, each s is independently 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11 or 12. In some cases, each s is 3. In some cases, each s is 4. In some cases, each s is 5. In some cases, each s is 6. In some cases, each s is 7. In some cases, each s is 8. In some cases, each s is 9. In some cases, each s is 10. In some cases, each s is 11. In some cases, each s is 12. In some cases, each s is 14. In some cases, each s is 16. In some embodiments, T 5  is an alkyl linker, such as a C1-C6 alkyl linker. In some embodiments, T 5  is a substituted alkyl linker. In some embodiments, T 5  is an alkoxy linker (e.g., —O— alkyl-). In some embodiments, T 5  is a substituted alkoxy. It is understood that hydroxy-terminated PEG chains instead of methoxy-terminated PEG chains may be utilized in any of the WSG groups described herein.
 
     In some cases, a WSG is a dendron selected from one of the following structures: 
                                           
In some cases, a WSG is a polyol selected from one of the following structures:
 
                         
In some cases, a WSG is an oxazoline of the following structure:
 
                         
In some cases, a WSG is a peptoid selected from one of the following structures:
 
     
       
         
         
             
             
         
       
     
     Aryl or Heteroaryl Co-Monomers 
     As summarized above, the subject polymeric dyes include conjugated segments of aryl or heteroaryl co-monomers linked via covalent bonds, vinylene groups or ethynylene groups. In addition to the co-monomers described in the exemplary formulae above, a variety of aryl and heteroaryl co-monomers find use in the subject polymeric dyes. Any convenient aryl and heteroaryl co-monomers may be utilized in the subject multichromophores, e.g., in a band gap modifying unit, and may be evenly or randomly distributed along the conjugated polymer as described herein. 
     In some embodiments of formula (I)-(XXI), the co-monomers M 2 , M 3  and M 4  are independently selected from one of formulae (XXIII)-(XXVI): 
                         
wherein
 
     Cy 2-7  is an aryl or heteroaryl group comprising 2 to 7 fused and/or unfused rings; 
     Y 2 , Y 3  and Y 4  are independently selected from —CR 3 —, NR 3 , N, O, S and —C(═O)— and together form a 5 or 6 membered fused aryl or heteraryl ring; 
     each R 3  is one or more ring substituents independently selected from H, halogen, alkyl, substituted alkyl, aryl, substituted aryl, heteroaryl, substituted heteroaryl, acyl, substituted acyl, sulfonic acid, cyano, alkoxy substituted alkoxy and -T 1 -Z 1 ; 
     R 1  and R 2  are independently selected from H, halogen, alkyl, substituted alkyl, aryl, substituted aryl, heteroaryl, substituted heteroaryl, acyl, substituted acyl, sulfonic acid, cyano, alkoxy, substituted alkoxy and -T 1 -Z 1 , or R 1  and R 2  together form a 5- or 6-membered fused aryl, heteroaryl, cycloalkyl or heterocycle ring which can be optionally substituted; 
     Y 5  is N or CR 5  and Y 7  is N or CR 7 ; 
     R 4 -R 7  are independently selected from H, halogen, alkyl, substituted alkyl, aryl, substituted aryl, heteroaryl, substituted heteroaryl, acyl, substituted acyl, sulfonic acid, cyano, alkoxy, substituted alkoxy and -T 1 -Z 1 ; 
     Z 1  is a chemoselective functional group or a linked signaling chromophore; and 
     T 1  is a linker. 
     Cy 2-7  is an aryl or heteroaryl group that can include 2, 3, 4, 5, 6 or 7 rings which can be fused together to form one fused ring system or may be unfused (i.e., linked together via single covalent bonds). In some cases, Cy 2-7  is includes 2 or 3 unfused aryl and/or heteroaryl rings. In certain instances, Cy 2-7  is composed of 5 and/or 6 membered carbocyclic and/or heterocyclic rings. In certain cases, Cy 2-7  is a bicyclic, tricyclic or quadricyclic aryl or heteroaryl group, such as naphthalene, anthracene, acridine, or quinoline, etc. 
     In certain embodiments of formulae (XXIII)-(XXVI), the co-monomers (M 2 , M 3  and M 4 ) are independently selected from one of the following structures (a) to (x): 
                                                                               
wherein:
 
     each Y 8  is independently C(R 3 ) 2 , —C(R 3 ) 2 C(R 3 ) 2 —, NR 3  or Si(R 3 ) 2 ; 
     X is S or O; 
     each R 3  is independently H, a water solubilizing group (e.g., as described herein), amino, substituted amino, halogen, cyano, alkyl, substituted alkyl, aryl, substituted aryl, heteroaryl, substituted heteroaryl, acyl, substituted acyl, sulfonic acid, cyano, alkoxy, substituted alkoxy and -T 1 -Z 1 ; 
     R 1  and R 2  are independently selected from H, halogen, alkyl, substituted alkyl, aryl, substituted aryl, heteroaryl, substituted heteroaryl, acyl, substituted acyl, sulfonic acid, cyano, alkoxy, substituted alkoxy and -T 1 -Z 1 , or R 1  and R 2  together form a 5- or 6-membered fused aryl, heteroaryl, cycloalkyl or heterocycle ring which can be optionally substituted (e.g., with an R 3  group); 
     Z 1  is a chemoselective functional group or a linked signaling chromophore; and 
     T 1  is a linker. 
     In certain instances, Y 8  is C(R 3 ) 2 . In certain instances, Y 8  is —C(R 3 ) 2 C(R 3 ) 2 —. In certain instances, Y 8  is NR 3 . In certain instances, Y 8  is Si(R 3 ) 2 . In certain embodiments of formula (a)-(x), when the co-monomer is a linking co-monomer, at least one of R 1 -R 7  is -T 1 -Z 1 . In certain embodiments of formula (a)-(x), the co-monomer includes a water-solubilizing group (e.g., as described herein). In certain embodiments of formula (s), R 3  is H, halogen (e.g., F) or alkoxy (e.g., methoxy). It is understood that in any of the structures of (a)-(x) described herein, a N heteroatom can be included to convert a phenyl or fused benzo ring into a pyridyl or fused pyrido ring. Such heteroatom substituted versions of formula (a)-(x) are meant to be included in the present disclosure. In some instances of formula (XXIII)-(XXVI), one or more of the co-monomers have the structure of one of formula (s), where a benzo ring is replaced with a pyrido ring: 
                         
where Y 8  is independently C(R 4 ) 2 , —C(R 4 ) 2 C(R 4 ) 2 —, NR 4  or Si(R 4 ) 2 .
 
     In some instances of formula (XXIII)-(XXVI) and (a)-(x), the co-monomers (M 2 , M 3  and M 4 ) are independently selected from one of the following structures (ba) to (cd): 
                                                                                                 
wherein:
 
     Y 9  is C(R 4 ) 2 , —C(R 4 ) 2 C(R 4 ) 2 — or Si(R 4 ) 2 ; 
     X is S or O; 
     each R 4  is independently H, a water solubilizing group (e.g., as described herein), alkyl, substituted alkyl, aryl, substituted aryl, heteroaryl, substituted heteroaryl, acyl, substituted acyl, sulfonic acid, cyano, alkoxy, substituted alkoxy and -T 1 -Z 1 ; and 
     R 1  and R 2  are independently selected from H, halogen, alkyl, substituted alkyl, aryl, substituted aryl, heteroaryl, substituted heteroaryl, acyl, substituted acyl, sulfonic acid, cyano, alkoxy, substituted alkoxy and -T 1 -Z 1 , or R 1  and R 2  together form a 5- or 6-membered fused aryl or heteroaryl ring which can be optionally substituted. In certain embodiments of formula (ba)-(cd), when the co-monomer is a linking co-monomer, at least one of R 4  is -T 1 -Z 1 . In certain embodiments of formula (ba)-(cd), R 4  includes a water-solubilizing group (e.g., as described herein). 
     The aryl and heteroaryl co-monomers described herein (e.g., co-monomers of formula (XXIII)-(XXVI), (a)-(x) and (ba)-(cd)) can include a water solubilizing group (e.g., as described herein). In certain instances of the co-monomers, each R 3  and each R 4  are independently selected from one of the following structures: 
                         
wherein: T 5  is an optional linker; and each s is an integer from 1 to 50. In certain instances, each s is independently 1 to 20, such as 3 to 20, 3 to 15, 3 to 12, or 6 to 12. In certain cases, each s is independently 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11 or 12. In some cases, each s is 3. In some cases, each s is 4. In some cases, each s is 5. In some cases, each s is 6. In some cases, each s is 7. In some cases, each s is 8. In some cases, each s is 9. In some cases, each s is 10. In some cases, each s is 11. In some embodiments, T 5  is an alkyl linker, such as a C1-C6 alkyl linker. In some embodiments, T 5  is a substituted alkyl linker. In some embodiments, T 5  is an alkoxy linker (e.g., —O— alkyl-). In some embodiments, T 5  is a substituted alkoxy.
 
     In certain embodiments of formula (I)-(XXII), the co-monomers (e.g., M 2 , M 3  and M 4 ) are independently selected from one of the following structures: 
     
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
     
     In some instances, the multichromophore (e.g., of formulae (V), (VII), (VIII), (IX), (XI), (XIII) and (XV)) includes a co-monomer (e.g., M 3  or M 4 ) linked to a signaling chromophore having the one of the following structures: 
                         
wherein WSG is an optional water soluble group; T 2  is a linker; and Dye is the signaling chromophore.
 
     In certain embodiments, the aryl or heteroaryl co-monomer is an optionally substituted co-monomer selected from 2,1,3-benzothiadiazole, 2,1,3-benzoxadiazole, benzoxidazole, benzoselenadiazole, benzotellurodiazole, naphthoselenadiazole, 4,7-di(thien-2-yl)-2,1,3-benzothiadiazole, squaraine dyes, quinoxalines, perylene, perylene diimides, diketopyrrolopyrrole, thienopyrazine low bandgap commercial dyes, olefins, and cyano-substituted olefins and isomers thereof. In some instances, aryl and heteroaryl co-monomers which find use in the subject multichromophores are selected from a′-k′ having the structure: 
                                                             
wherein *=a site for covalent attachment to unsaturated backbone and each R is independently H, a non-ionic side group capable of imparting solubility in water (e.g., a WSG), or -L 2 -Z 2 , where L 2  is a linker and Z 2  is a chemoselective tag or a linked metal complex. In certain instances of a′-k′, each R is H or a water solubilizing group (e.g., as described herein). In certain cases, each R is an alkyl or a benzyl substituted with one or more (CH 2 ) x (OCH 2 CH 2 ) y OCH 3  where each x is independently an integer from 0-20, each y is independently an integer from 0 to 50. In certain instances of a′-k′, each R is (CH 2 ) 3 (OCH 2 CH 2 ) 11 OCH 3 .
 
     In some embodiments, the multichromophore includes an absorbance-modifying co-monomer having the following structure: 
                         
where X is O or S, R 41  and R 42  are each independently, H, halogen, a WSG, an alkyl, a substituted alkyl, an alkoxy and a substituted alkoxy. In certain instances, X is O. In some instances, X is S. In certain embodiments, X is O and R 41  and R 42  are each H. In certain embodiments, X is S and R 41  and R 42  are each H.
 
     In some instances, the aryl or heteroaryl co-monomer is a substituted or unsubstituted phenyl, biphenyl or pyridyl co-monomer. In certain embodiments, the aryl or heteroaryl co-monomer is selected from substituted or unsubstituted 1,4-phenyl, a substituted or unsubstituted 1,3-phenyl, a substituted or unsubstituted 4,4′-biphenyl, a substituted or unsubstituted 2,5-pyridyl, and a substituted or unsubstituted 2,6-pyridyl. In certain instances, the absorbance-modifying co-monomer is an optionally substituted aryl or heteroaryl co-monomer selected from one of the following structures: 
     
       
         
         
             
             
         
       
     
     where Z 2 —Z 5  are each independently CR or N, where at least one Z 2 —Z 5  is N; and each R and each R 11 -R 16  are independently selected from the group consisting of hydrogen, water solubilizing group, halogen, cyano, alkoxy, substituted alkoxy, alkyl and substituted alkyl. In certain embodiments, one and only one of Z 2 —Z 5  is N. In certain embodiments, two and only two of Z 2 —Z 5  is N. In certain instances, R 11 , R 12  and R 14  are each H. In some instances, R 12  and R 14  are each H. In some instances, R 11  and R 13  are each H. In some cases, R 15  and R 16  are each H. In some instances, the halogen is fluoro. 
     In some cases, the aryl or heteroaryl co-monomer selected from one of the following: 
                                           
where n is 1-20 and R′ is H or lower alkyl. In some embodiments of the aryl or heteroaryl co-monomer structures, n is an integer from 3 to 20.
 
     In some embodiments, the multichromophore includes a substituted aryl co-monomer described by the following structure: 
                         
where n is 1-20 and R′ is H or lower alkyl. In certain instances, n is 3 to 12. In some embodiments, the multichromophore includes a substituted aryl co-monomer described by the following structure:
 
                         
where each n is independently 1-20 and each R′ is independently H or lower alkyl. In certain embodiments of the substituted aryl or heteroaryl co-monomer structures shown above, n is 3. In certain instances, R′ is methyl. In certain instances, R′ is hydrogen. In some embodiments, the multichromophore includes a substituted aryl co-monomer described by the following structure:
 
                         
In some embodiments, the multichromophore includes a substituted aryl co-monomer described by the following structure:
 
                         
Any of the absorbance-modifying co-monomers described above may be utilized in the subject multichromophores, e.g., multichromophores of formulae (I)-(XXII).
 
     Polymeric Tandem Dyes 
     The water soluble light harvesting multichromophore can itself be fluorescent and capable of transferring energy to a linked acceptor signaling chromophore. As such, the subject polymeric tandem dyes further include a covalently linked acceptor signaling chromophore in energy-receiving proximity to the donor water solvated light harvesting multichromophore. As such, excitation of the multichromophore donor leads to energy transfer to and emission from the covalently attached acceptor signaling chromophore. The number of signaling chromophore acceptor units that are linked to the donor water solvated light harvesting multichromophore may vary, where in some instances the number ranges from 1 mol % to 50 mol %, such as from 5 mol % to 25 mol % or from 10 mol % to 25 mol %. 
     Mechanisms for energy transfer from the fluorescent water solvated light harvesting multichromophore donor to the linked acceptor signaling chromophore include, for example, resonant energy transfer (e.g., Förster (or fluorescence) resonance energy transfer, FRET), quantum charge exchange (Dexter energy transfer) and the like. In some instances, these energy transfer mechanisms are relatively short range; that is, close proximity of the light harvesting multichromophore system to the acceptor provides for efficient energy transfer. In some instances, under conditions for efficient energy transfer, amplification of the emission from the acceptor occurs where the emission from the luminescent signaling chromophore is more intense when the incident light (the “pump light”) is at a wavelength which is absorbed by the light harvesting multichromophore than when the luminescent signaling chromophore is directly excited by the pump light. 
     By “efficient” energy transfer is meant 10% or more, such as 20% or more or 30% or more, of the energy harvested by the donor is transferred to the acceptor. By “amplification” is meant that the signal from the signaling chromophore is 1.5× or greater when excited by energy transfer from the donor light harvesting multichromophore as compared to direct excitation with incident light of an equivalent intensity. The signal may be measured using any convenient method. In some cases, the 1.5× or greater signal refers to an intensity of emitted light. In certain cases, the 1.5× or greater signal refers to an increased signal to noise ratio. In certain embodiments of the polymeric tandem dye, the signaling chromophore emission is 1.5 fold greater or more when excited by the multichromophore as compared to direct excitation of the signaling chromophore with incident light, such as 2-fold or greater, 3-fold or greater, 4-fold or greater, 5-fold or greater, 6-fold or greater, 8-fold or greater, 10-fold or greater, 20-fold or greater, 50-fold or greater, 100-fold or greater, or even greater as compared to direct excitation of the signaling chromophore with incident light. 
     The linked luminescent signaling chromophore emission of the polymeric tandem dye can have a quantum yield of 0.03 or more, such as a quantum yield of 0.04 or more, 0.05 or more, 0.06 or more, 0.07 or more, 0.08 or more, 0.09 or more, 0.1 or more, 0.15 or more, 0.2 or more, 0.3 or more or even more. In some instances, the polymeric tandem dye has an extinction coefficient of 5×10 5  cm −1 M −1  or more, such as 6×10 5  cm 1 M −1  or more, 7×10 5  cm −1 M −1  or more, 8×10 5  cm −1 M −1  or more, 9×10 5  cm −1 M −1  or more, such as 1×10 6  cm −1 M −1  or more, 1.5×10 6  cm −1 M −1  or more, 2×10 6  cm −1 M −1  or more, 2.5×10 6  cm −1 M −1  or more, 3×10 6  cm −1 M −1  or more, 4×10 6  cm −1 M −1  or more, 5×10 6  cm −1 M −1  or more, 6×10 6  cm −1 M −1  or more, 7×10 6  cm −1 M −1  or more, or 8×10 6  cm −1 M −1  or more. In some embodiments, the polymeric tandem dye has a molar extinction coefficient of 5×10 5  M −1  cm −1  or more. In certain embodiments, the polymeric tandem dye has a molar extinction coefficient of 1×10 6  M −1  cm −1  or more. 
     The subject polymeric tandem dyes provide for fluorescence emissions from luminescent signaling chromophore dyes that are brighter than the emissions which are possible from such luminescent dyes in isolation. The linked luminescent signaling chromophore emission of the polymeric tandem dye can have a brightness of 50 mM −1  cm −1  or more, such as 60 mM −1  cm −1  or more, 70 mM −1  cm −1  or more, 80 mM −1  cm −1  or more, 90 mM −1  cm −1  or more, 100 mM −1  cm −1  or more, 150 mM −1  cm −1  or more, 200 mM −1  cm −1  or more, 250 mM −1  cm −1  or more, 300 mM −1  cm −1  or more, or even more. In certain instances, the linked signaling chromophore emission of the polymeric tandem dye has a brightness that is at least 5-fold greater than the brightness of a directly excited luminescent dye, such as at least 10-fold greater, at least 20-fold greater, at least 30-fold greater, at least 50-fold greater, at least 100-fold greater, at least 300-fold greater, or even greater than the brightness of a directly excited luminescent dye. 
     In some embodiments, a polymeric tandem dye includes: a water soluble light harvesting multichromophore comprising a conjugated segment having the structure of formula (I): 
     
       
         
         
             
             
         
       
     
     wherein:
         each L is independently a conjugated backbone linking unit selected from a covalent bond, a vinylene group and an ethynylene group;   M 1  and M 2  are independently an aryl co-monomer or heteroaryl co-monomer;   each * is a site for covalent attachment to the unsaturated backbone of a conjugated polymer; and   n is an integer from 1 to 100,000; and       

     a signaling chromophore covalently linked to the multichromophore in energy-receiving proximity therewith. 
     In certain embodiments of formula (I)-(XXVI) and (a)-(w) and (ba)-(cb), a linked signaling chromophore (e.g., as described herein) is included as a substituent of a co-monomer. Any convenient signaling chromophore can be attached to any convenient polymer dye described herein via coupling of compatible chemoselective functional groups. The signaling chromophore can be selected to provide for a desirable emission spectra and emission maximum wavelength. 
     As used herein, the terms “chemoselective functional group” and “chemoselective tag” are used interchangeably and refer to a functional group that can selectively react with another compatible functional group to form a covalent bond, in some cases, after optional activation of one of the functional groups. Chemoselective functional groups of interest include, but are not limited to, thiols and maleimide or iodoacetamide, amines and carboxylic acids or active esters thereof, as well as groups that can react with one another via Click chemistry, e.g., azide and alkyne groups (e.g., cyclooctyne groups), as well as hydroxyl, hydrazido, hydrazino, aldehyde, ketone, azido, alkyne, phosphine, epoxide, and the like. 
     Any convenient linking co-monomers may be incorporated into the subject multichromophores to provide for a linking group to which may be attached any convenient moieties of interest (e.g., a linked signaling chromophore). Linking co-monomers of interest include, but are not limited to, those co-monomers described in the formula herein, and a fluorene co-monomer, a phenylenevinylene co-monomer, a phenyleneethynylene co-monomer, a carbazole co-monomer, a C 2 -C 12  alkyne co-monomer, an arylene-ethynylene co-monomer, a heteroarylene-ethynylene co-monomer, an arylene co-monomer and a heteroarylene co-monomer. As used herein, the terms aryl or heteroaryl co-monomer and arylene or heteroarylene co-monomer are used interchangeably. In certain cases, the linking co-monomer is a substituted aryl co-monomer. In certain cases, the linking co-monomer is a substituted heteroaryl co-monomer. In certain cases, the linking co-monomer is a substituted or unsubstituted 1,4-phenyl, a substituted or unsubstituted 1,3-phenyl, a substituted or unsubstituted 4,4′-biphenyl, a substituted or unsubstituted 2,5-pyridyl, and a substituted or unsubstituted 2,6-pyridyl. 
     In some instances of any of the formula described herein, the signaling chromophore is linked to a co-monomer comprising 1% to 50% by molarity of the multichromophore, such as 1% to 20%, 1% to 10%, or 11 to 20% by molarity. In certain cases, the multichromophore is a conjugated polymer comprising 5 or more repeat units. 
     Any convenient chemoselective functional groups may be included in the subject multichromophores (e.g., at the —Z 1 , —Z 2  and/or in the G 1  or G 2  terminal groups, including, but are not limited to, carboxylic acid, active ester (e.g., NHS or sulfo-NHS ester), amino, hydroxyl, thiol, maleimide, iodoacetyl, hydrazido, hydrazino, aldehyde, ketone, azido, alkyne, phosphine and epoxide. It is understood that in the polymeric tandem dye structures described herein, in some cases, the groups Z 1  and Z 2  appear at a equivalent position in the structure where these groups can be used interchangeably to refer to either a linked signaling chromophore or a chemoselective functional group that is capable of subsequent conjugation to a convenient chromophore precursor to produce the linked signaling chromophore. 
     In some cases, the signaling chromophore is a fluorophore. In certain cases, the signaling chromophore is a quencher. Any convenient fluorescent dyes may be utilized in the polymeric tandem dyes as an acceptor chromophore. The terms “fluorescent dye” and “fluorophore” are used interchangeably herein. The signaling chromophore (Z 1 ) can be a dye molecule selected from a rhodamine, a coumarin, a xanthene, a cyanine, a polymethine, a pyrene, a dipyrromethene borondifluoride, a napthalimide, a phycobiliprotein, a peridinum chlorophyll protein, conjugates thereof, and combinations thereof. In certain embodiments, the signaling chromophore (Z 1 ) is a cyanine dye, a xanthene dye, a coumarin dye, a thiazine dye and an acridine dye. In some instances, the signaling chromophore (Z 1 ) is selected from DY 431, DY 485XL, DY 500XL, DY 610, DY 640, DY 654, DY 682, DY 700, DY 701, DY 704, DY 730, DY 731, DY 732, DY 734, DY 752, DY 778, DY 782, DY 800, DY 831, Biotium CF 555, Cy 3.5 and diethylamino coumarin. In some embodiments, the acceptor chromophore is a cyanine dye, a xanthene dye, a coumarin dye, a thiazine dye or an acridine dye. Fluorescent dyes of interest include, but are not limited to, fluorescein, 6-FAM, rhodamine, Texas Red, tetramethylrhodamine, carboxyrhodamine, carboxyrhodamine 6G, carboxyrhodol, carboxyrhodamine 110, Cascade Blue, Cascade Yellow, coumarin, Cy2, Cy3, Cy3.5, Cy5, Cy5.5, Cy-Chrome, phycoerythrin, PerCP (peridinin chlorophyll-a Protein), PerCP-Cy5.5, JOE (6-carboxy-4′,5′-dichloro-2′,7′-dimethoxyfluorescein), NED, ROX (5-(and -6)-carboxy-X-rhodamine), HEX, Lucifer Yellow, Marina Blue, Oregon Green 488, Oregon Green 500, Oregon Green 514, Alexa Fluor 350, Alexa Fluor 430, Alexa Fluor 488, Alexa Fluor 532, Alexa Fluor 546, Alexa Fluor 568, Alexa Fluor 594, Alexa Fluor 633, Alexa Fluor 647, Alexa Fluor 660, Alexa Fluor 680, Alexa Fluor 700, 7-amino-4-methylcoumarin-3-acetic acid, BODIPY FL, BODIPY FL-Br.sub.2, BODIPY 530/550, BODIPY 558/568, BODIPY 564/570, BODIPY 576/589, BODIPY 581/591, BODIPY 630/650, BODIPY 650/665, BODIPY R6G, BODIPY TMR, BODIPY TR, conjugates thereof, and combinations thereof. Lanthanide chelates of interest include, but are not limited to, europium chelates, terbium chelates and samarium chelates. In some embodiments, the polymeric tandem dye includes a polymeric dye linked to an acceptor fluorophore selected from Cy3, Cy3.5, Cy5, Cy5.5, Cy7, Alexa488, Alexa 647 and Alexa700. In certain embodiments, the polymeric tandem dye includes a polymeric dye linked to an acceptor fluorophore selected from Dyomics dyes (such as DY 431, DY 485XL, DY 500XL, DY 530, DY 610, DY 633, DY 640, DY 651, DY 654, DY 682, DY 700, DY 701, DY 704, DY 730, DY 731, DY 732, DY 734, DY 752, DY 754, DY 778, DY 782, DY 800 or DY 831), Biotium CF 555, Cy 3.5, and diethylamino coumarin. 
     In some embodiments, the signaling chromophore that is selected has an emission maximum wavelength in the range of 300 to 900 nm, such as 350 to 850 nm, 350 to 600 nm, 360 to 500 nm, 370 to 500 nm, 380 to 500 nm, 390 to 500 nm or 400 to 500 nm, where specific examples of emission maxima of signaling chromophore of interest include, but are not limited to: 395 nm±5 nm, 420 nm±5 nm, 430 nm±5 nm, 440 nm±5 nm, 450 nm±5 nm, 460 nm±5 nm, 470 nm±5 nm, 480 nm±5 nm, 490 nm±5 nm, 500 nm±5 nm, 510 nm±5 nm, 520 nm±5 nm, 530 nm±5 nm, 540 nm±5 nm, 550 nm±5 nm, 560 nm±5 nm, 570 nm±5 nm, 580 nm±5 nm, 590 nm±5 nm, 605 nm±5 nm, 650 nm±5 nm, 680 nm±5 nm, 700 nm±5 nm, 805 nm±5 nm. 
     End Groups 
     Any convenient end groups (e.g., G 1  and G 2 ) may be utilized at the terminals of the subject multichromophores. As used herein, the terms “end group” and “terminal group” are used interchangeably to refer to the groups located at the terminals of the polymeric structure of the multichromophore, e.g., as described herein. G 1  and G 2  groups of interest include, but are not limited to a terminal capping group, a π conjugated segment, a linker and a linked specific binding member. In some embodiments, a terminal capping groups is a monovalent group which is conjugated to the backbone of the multichromophore after polymerization. In certain instances, the terminal capping group is an aryl, a substituted aryl, a heteroaryl, a substituted heteroaryl, an alkyl or a substituted alkyl. In some cases, the terminal co-monomer is directed linked to a chemoselective tag or linker. In certain cases, the terminal capping group is derived from a monomer used in the method of polymerization, e.g., a terminal group such as a halogen (e.g., Br), a boronic acid or a boronic ester, which is capable of undergoing further conjugation. In some instances, G′ and/or G 2  is a π conjugated segment. As used herein, a π conjugated segment refers to any convenient segment of a conjugated polymer to which the multichromophore may be conjugated, i.e., allowing delocalization of pi electron across adjacent units. In certain embodiments, G′ and/or G 2  is a linker, such as a linker including a functional group suitable for conjugation to a specific binding moiety. It is understood that linkers located at the G′ and/or G 2  positions of the multichromophore may be selected so as to be orthogonal to any other linkers including chemoselective tags (e.g., as described herein) that may be present at a sidechain of the multichromophore (e.g., at Z 2 ). In certain embodiments, an amino functional group or derivative thereof is included at G 1  and/or G 2  and a carboxylic acid functional group or derivative thereof is included at Z 2 . In certain embodiments, a carboxylic acid functional group or derivative thereof is included at G 1  and/or G 2  and an amino functional group or derivative thereof is included at Z 2 . 
     In some embodiments of the formulae described herein, at least one of G 1  and G 2  is -L 3 -Z 4  where L 3  is a linker (e.g., as described herein) and Z 4  is a specific binding member (e.g., as described herein). In some embodiments of formulae described herein, at least one of G 1  and G 2  is -L 3 -Z 3  where L 3  is a linker (e.g., as described herein) and Z 3  is a chemoselective tag (e.g., as described herein). Any convenient chemoselective tag and conjugation chemistries can be adapted for use in the subject multichromophores. Chemoselective tags of interest include, but are not limited to, amine, active ester, maleimide, thiol, sulfur(VI) fluoride exchange chemistry (SuFEX), sulfonyl fluoride, tetrazine, aldehyde, alkoxylamine, alkynes, cyclooctynes, azide, and the like. In some instances, Z 3  is selected from the group consisting of carboxylic acid, active ester (e.g., N-hydroxy succinimidyl ester (NHS) or sulfo-NHS), amino, maleimide, iodoacetyl and thiol. In certain embodiments of formulae described herein, at least one of G 1  and G 2  is described by the following structure:
 
*—Ar-L-Z
 
     where Ar is a π-conjugated aryl group, L is a linker and Z is a chemoselective tag or a specific binding member. In some cases, the L-Z group can be connected directed to a terminal co-monomer. In certain embodiments of formulae described herein, at least one of G 1  and G 2  is described by the following structure: 
     
       
         
         
             
             
         
       
     
     wherein: 
     q is 0 or an integer from 1-12; 
     L is an optional linker; and 
     Z is a chemoselective tag or a specific binding member. 
     In certain embodiments, Z is a biomolecule. Biomolecules of interest include, but are not limited to, polypeptides, polynucleotides, carbohydrates, fatty acids, steroids, purines, pyrimidines, derivatives, structural analogs thereof and combinations thereof. In certain instances, Z is an antibody. In some instances, Z is an antibody fragment or binding derivative thereof. In some cases, the antibody fragment or binding derivative thereof is selected from the group consisting of a Fab fragment, a F(ab′) 2  fragment, a scFv, a diabody and a triabody. 
     It is understood that for any of the structures and formula depicted herein that in some cases of the subject multichromophore the end groups depicted may be located at the opposite ends to those shown, e.g., the end groups G 1  and -Ph-L-Z may be switched. In some embodiments of the multichromophores described herein (e.g., formulae (V), (VII) and (VIII)), at least one of G 1  and G 2  is selected from one of the following structures 1-33: 
                                                             
*=site for covalent attachment to unsaturated backbone;
 
wherein R′ is independently H, halogen, C 1 -C 12 alkyl, (C 1 -C 12 alkyl)NH 2 , C 2 -C 12 alkene, C 2 -C 12  alkyne, C 3 -C 12 cycloalkyl, C 1 -C 12  haloalkyl, C 2 -C 18 (hetero)aryl, C 2 -C 18 (hetero)arylamino, —[CH 2 —CH 2 ] r —Z 1 , or (C 1 -C 12 )alkoxy-X 1 ; and wherein Z 1  is —OH or —COOH; X 1  is —NH 2 , —NHCOOH, —NHCOOC(CH 3 ) 3 , —NHCO(C3-C12)cycloalkyl(C1-C4)alkyl-N-maleimide; or —NHCO[CH 2 —CH 2 —O] s′ (CH 2 ) s′ NH 2 ; r′ is an integer from 1 to 20; and each s′ is independently an integer from 1 to 20, (CH 2 ) 3 (OCH 2 CH 2 ) x″ OCH 3  where x″ is independently an integer from 0 to 50, or a benzyl optionally substituted with one or more halogen, hydroxyl, C 1 -C 12  alkoxy, or (OCH 2 CH 2 ) y″ , CH 3  where each y″ is independently an integer from 0 to 50 and R′ is different from R;
 
wherein k is 2, 4, 8, 12 or 24;
 
wherein R 15  is selected from the group consisting of I-u having the structure:
 
                         
*=site for covalent attachment to backbone.
 
     In some embodiments of the multichromophores described herein (e.g., formulae (V)-(XVI), at least one end group (e.g., T 2 -Z 2 , G 1 , G 2 , -L-Z, -L 3 -Z 3 ), or sidechain group, is selected from one of the following structures: 
                                           
wherein r is 0 or an integer from 1-50; k is 0 or an integer from 1-50 (e.g., 1-20); R 1  is as defined for any of the fluorene co-monomers described herein; and R 16  is selected from H, OH, NH 2 , —NH(CH 2 ) r —NH 2 , and —NH(CH 2 ) r COOH. In certain instances, r is 1 to 20, such as 3 to 20, 3 to 15, 3 to 12, or 6 to 12. In certain cases, r is 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11 or 12. In some cases, r is 3. In some cases, r is 4. In some cases, r is 5. In some cases, r is 6. In some cases, r is 7. In some cases, r is 8. In some cases, r is 9. In some cases, r is 10. In some cases, r is 11.
 
     Labeled Specific Binding Members 
     Aspects of the present disclosure include labeled specific binding members. A labeled specific binding member is a conjugate of a subject polymeric dye (e.g., as described herein) and a specific binding member. Any of the polymeric dyes or polymeric tandem dyes described herein may be conjugated to a specific binding member. The specific binding member and the polymeric dye can be conjugated (e.g., covalently linked) to each other at any convenient locations of the two molecules, via an optional linker. 
     As used herein, the term “specific binding member” refers to one member of a pair of molecules which have binding specificity for one another. One member of the pair of molecules may have an area on its surface, or a cavity, which specifically binds to an area on the surface of, or a cavity in, the other member of the pair of molecules. Thus the members of the pair have the property of binding specifically to each other to produce a binding complex. In some embodiments, the affinity between specific binding members in a binding complex is characterized by a K d  (dissociation constant) of 10 −6  M or less, such as 10 −7  M or less, including 10 −8  M or less, e.g., 10 −9  M or less, 10 −10  M or less, 10 −11  M or less, 10 −12  M or less, 10 −13  M or less, 10 −14  M or less, including 10 −15  M or less. In some embodiments, the specific binding members specifically bind with high avidity. By high avidity is meant that the binding member specifically binds with an apparent affinity characterized by an apparent K d  of 10×10 −9  M or less, such as 1×10 −9  M or less, 3×10 −10  M or less, 1×10 −10  M or less, 3×10 −11  M or less, 1×10 −11  M or less, 3×10 −12  M or less or 1×10 −12  M or less. 
     The specific binding member can be proteinaceous. As used herein, the term “proteinaceous” refers to a moiety that is composed of amino acid residues. A proteinaceous moiety can be a polypeptide. In certain cases, the proteinaceous specific binding member is an antibody. In certain embodiments, the proteinaceous specific binding member is an antibody fragment, e.g., a binding fragment of an antibody that specific binds to a polymeric dye. As used herein, the terms “antibody” and “antibody molecule” are used interchangeably and refer to a protein consisting of one or more polypeptides substantially encoded by all or part of the recognized immunoglobulin genes. The recognized immunoglobulin genes, for example in humans, include the kappa (k), lambda (l), and heavy chain genetic loci, which together comprise the myriad variable region genes, and the constant region genes mu (u), delta (d), gamma (g), sigma (e), and alpha (a) which encode the IgM, IgD, IgG, IgE, and IgA isotypes respectively. An immunoglobulin light or heavy chain variable region consists of a “framework” region (FR) interrupted by three hypervariable regions, also called “complementarity determining regions” or “CDRs”. The extent of the framework region and CDRs have been precisely defined (see, “Sequences of Proteins of Immunological Interest,” E. Kabat et al., U.S. Department of Health and Human Services, (1991)). The numbering of all antibody amino acid sequences discussed herein conforms to the Kabat system. The sequences of the framework regions of different light or heavy chains are relatively conserved within a species. The framework region of an antibody, that is the combined framework regions of the constituent light and heavy chains, serves to position and align the CDRs. The CDRs are primarily responsible for binding to an epitope of an antigen. The term antibody is meant to include full length antibodies and may refer to a natural antibody from any organism, an engineered antibody, or an antibody generated recombinantly for experimental, therapeutic, or other purposes as further defined below. 
     Antibody fragments of interest include, but are not limited to, Fab, Fab′, F(ab′)2, Fv, scFv, or other antigen-binding subsequences of antibodies, either produced by the modification of whole antibodies or those synthesized de novo using recombinant DNA technologies. Antibodies may be monoclonal or polyclonal and may have other specific activities on cells (e.g., antagonists, agonists, neutralizing, inhibitory, or stimulatory antibodies). It is understood that the antibodies may have additional conservative amino acid substitutions which have substantially no effect on antigen binding or other antibody functions. 
     In certain embodiments, the specific binding member is a Fab fragment, a F(ab′) 2  fragment, a scFv, a diabody or a triabody. In certain embodiments, the specific binding member is an antibody. In some cases, the specific binding member is a murine antibody or binding fragment thereof. In certain instances, the specific binding member is a recombinant antibody or binding fragment thereof. 
     In some embodiments, the labeled specific binding member includes: a water solvated light harvesting multichromophore (e.g., as described herein); and a signaling chromophore covalently linked to the multichromophore in energy-receiving proximity therewith (e.g., as described herein); and a specific binding member covalently linked to the multichromophore. In some instances of the labeled specific binding member, the multichromophore of any of the formula described herein (e.g., formulae (V) and (VII)-(VIII)), wherein: G 1  and G 2  are each independently selected from the group consisting of a terminal group (e.g., end group), a π conjugated segment, a linker and a linked specific binding member, wherein at least one of G 1  and G 2  is a linked specific binding member. 
     Methods 
     As summarized above, aspects of the invention include methods of evaluating a sample for the presence of a target analyte. Aspects of the method include contacting the sample with a polymeric dye conjugate that specifically binds the target analyte to produce a labeling composition contacted sample. As used herein, the terms “polymeric dye conjugate” and “labeled specific binding member” are used interchangeably. As such, the polymeric dye conjugate can include: (i) a water solvated polymeric dye (e.g., as described herein); and (ii) a specific binding member (e.g., as described herein). In some instances, the polymeric dye conjugate further comprises a signaling chromophore covalently linked to a multichromophore of the polymeric dye in energy-receiving proximity therewith. 
     Any convenient method may be used to contact the sample with a polymeric dye conjugate that specifically binds to the target analyte to produce the labeling composition contacted sample. In some instances, the sample is contacted with the polymeric dye conjugate under conditions in which the specific binding member specifically binds to the target analyte, if present. For specific binding of the specific binding member of the conjugate with the target analyte, an appropriate solution may be used that maintains the biological activity of the components of the sample and the specific binding member. The solution may be a balanced salt solution, e.g., normal saline, PBS, Hank&#39;s balanced salt solution, etc., conveniently supplemented with fetal calf serum, human platelet lysate or other factors, in conjunction with an acceptable buffer at low concentration, such as from 5-25 mM. Convenient buffers include HEPES, phosphate buffers, lactate buffers, etc. Various media are commercially available and may be used according to the nature of the target analyte, including dMEM, HBSS, dPBS, RPMI, Iscove&#39;s medium, etc., in some cases supplemented with fetal calf serum or human platelet lysate. The final components of the solution may be selected depending on the components of the sample which are included. 
     The temperature at which specific binding of the specific binding member of the conjugate to the target analyte takes place may vary, and in some instances may range from 5° C. to 50° C., such as from 10° C. to 40° C., 15° C. to 40° C., 20° C. to 40° C., e.g., 20° C., 25° C., 30° C., 35° C. or 37° C. (e.g., as described above). In some instances, the temperature at which specific binding takes place is selected to be compatible with the biological activity of the specific binding member and/or the target analyte. In certain instances, the temperature is 25° C., 30° C., 35° C. or 37° C. In certain cases, the specific binding member is an antibody or fragment thereof and the temperature at which specific binding takes place is room temperature (e.g., 25° C.), 30° C., 35° C. or 37° C. Any convenient incubation time for specific binding may be selected to allow for the formation of a desirable amount of binding complex, and in some instances, may be 1 minute (min) or more, such as 2 min or more, 10 min or more, 30 min or more, 1 hour or more, 2 hours or more, or even 6 hours or more. 
     Any convenient specific binding members may be utilized in the conjugate. Specific binding members of interest include, but are not limited to, those agents that specifically bind cell surface proteins of a variety of cell types, including but not limited to, stem cells, e.g., pluripotent stem cells, hematopoietic stem cells, T cells, T regulator cells, dendritic cells, B Cells, e.g., memory B cells, antigen specific B cells, granulocytes, leukemia cells, lymphoma cells, virus cells (e.g., HIV cells) NK cells, macrophages, monocytes, fibroblasts, epithelial cells, endothelial cells, and erythroid cells. Target cells of interest include cells that have a convenient cell surface marker or antigen that may be captured by a convenient specific binding member conjugate. In some embodiments, the target cell is selected from HIV containing cell, a Treg cell, an antigen-specific T-cell populations, tumor cells or hematopoetic progenitor cells (CD34+) from whole blood, bone marrow or cord blood. Any convenient cell surface proteins or cell markers may be targeted for specific binding to polymeric dye conjugates in the subject methods. In some embodiments, the target cell includes a cell surface marker selected from a cell receptor and a cell surface antigen. In some cases, the target cell may include a cell surface antigen such as CD11 b, CD123, CD14, CD15, CD16, CD19, CD193, CD2, CD25, CD27, CD3, CD335, CD36, CD4, CD43, CD45RO, CD56, CD61, CD7, CD8, CD34, CD1c, CD23, CD304, CD235a, T cell receptor alpha/beta, T cell receptor gamma/delta, CD253, CD95, CD20, CD105, CD117, CD120b, Notch4, Lgr5 (N-Terminal), SSEA-3, TRA-1-60 Antigen, Disialoganglioside GD2 and CD71. 
     Any convenient targets may be selected for evaluation utilizing the subject methods. Targets of interest include, but are not limited to, a nucleic acid, such as an RNA, DNA, PNA, CNA, HNA, LNA or ANA molecule, a protein, such as a fusion protein, a modified protein, such as a phosphorylated, glycosylated, ubiquitinated, SUMOylated, or acetylated protein, or an antibody, a peptide, an aggregated biomolecule, a cell, a small molecule, a vitamin and a drug molecule. As used herein, the term “a target protein” refers to all members of the target family, and fragments thereof. The target protein may be any protein of interest, such as a therapeutic or diagnostic target, including but not limited to: hormones, growth factors, receptors, enzymes, cytokines, osteoinductive factors, colony stimulating factors and immunoglobulins. The term “target protein” is intended to include recombinant and synthetic molecules, which can be prepared using any convenient recombinant expression methods or using any convenient synthetic methods, or purchased commercially. In some embodiments, the polymeric dye conjugates include an antibody or antibody fragment. Any convenient target analyte that specifically binds an antibody or antibody fragment of interest may be targeted in the subject methods. 
     In some embodiments, the target analyte is associated with a cell. In certain instances, the target analyte is a cell surface marker of the cell. In certain cases, the cell surface marker is selected from the group consisting of a cell receptor and a cell surface antigen. In some instances, the target analyte is an intracellular target, and the method further includes lysing the cell. 
     In some embodiments, the sample may include a heterogeneous cell population from which target cells are isolated. In some instances, the sample includes peripheral whole blood, peripheral whole blood in which erythrocytes have been lysed prior to cell isolation, cord blood, bone marrow, density gradient-purified peripheral blood mononuclear cells or homogenized tissue. In some cases, the sample includes hematopoetic progenitor cells (e.g., CD34+ cells) in whole blood, bone marrow or cord blood. In certain embodiments, the sample includes tumor cells in peripheral blood. In certain instances, the sample is a sample including (or suspected of including) viral cells (e.g., HIV). 
     The labeled specific binding members find use in the subject methods, e.g., for labeling a target cell, particle, target or analyte with a polymeric dye or polymeric tandem dye. For example, labeled specific binding members find use in labeling cells to be processed (e.g., detected, analyzed, and/or sorted) in a flow cytometer. The labeled specific binding members may include antibodies that specifically bind to, e.g., cell surface proteins of a variety of cell types (e.g., as described herein). The labeled specific binding members may be used to investigate a variety of biological (e.g., cellular) properties or processes such as cell cycle, cell proliferation, cell differentiation, DNA repair, T cell signaling, apoptosis, cell surface protein expression and/or presentation, and so forth. Labeled specific binding members may be used in any application that includes (or may include) antibody-mediated labeling of a cell, particle or analyte. 
     In some instances of the method, the labeled specific binding member includes a multichromophore according to any one of formulae (I)-(XXII) (e.g., as described herein). In certain cases, G 1  and G 2  are each independently selected from the group consisting of a terminal group, a π conjugated segment, a linker and a linked specific binding member, wherein at least one of G 1  and G 2  is a linked specific binding member. 
     Aspects of the method include assaying the labeling composition contacted sample for the presence of a polymeric dye conjugate-target analyte binding complex to evaluate whether the target analyte is present in the sample. Once the sample has been contacted with the polymeric dye conjugate, any convenient methods may be utilized in assaying the labeling composition contacted sample that is produced for the presence of a polymeric dye conjugate-target analyte binding complex. The polymeric dye conjugate-target analyte binding complex is the binding complex that is produced upon specific binding of the specific binding member of the conjugate to the target analyte, if present. Assaying the labeling composition contacted sample can include detecting a fluorescent signal from the binding complex, if present. In some cases, the assaying includes a separating step where the target analyte, if present, is separated from the sample. A variety of methods can be utilized to separate a target analyte from a sample, e.g., via immobilization on a support. Assay methods of interest include, but are not limited to, any convenient methods and assay formats where pairs of specific binding members such as avidin-biotin or hapten-anti-hapten antibodies find use, are of interest. Methods and assay formats of interest that may be adapted for use with the subject compositions include, but are not limited to, flow cytometry methods, in-situ hybridization methods, enzyme-linked immunosorbent assays (ELISAs), western blot analysis, magnetic cell separation assays and fluorochrome purification chromatography. 
     In certain embodiments, the method further includes contacting the sample with a second specific binding member that specifically binds the target analyte. In certain instances, the second specific binding member is support bound. Any convenient supports may be utilized to immobilize a component of the subject methods (e.g., a second specific binding member). In certain instances, the support is a particle, such as a magnetic particle. In some instances, the second specific binding member and the polymeric dye conjugate produce a sandwich complex that may be isolated and detected, if present, using any convenient methods. In some embodiments, the method further includes flow cytometrically analyzing the polymeric dye conjugate-target analyte binding complex, i.e., a fluorescently labeled target analyte. Assaying for the presence of a polymeric dye conjugate-target analyte binding complex may provide assay results (e.g., qualitative or quantitative assay data) which can be used to evaluate whether the target analyte is present in the sample. 
     Any convenient supports may be utilized in the subject methods to immobilize any convenient component of the methods, e.g., labeled specific binding member, target, secondary specific binding member, etc. Supports of interest include, but are not limited to: solid substrates, where the substrate can have a variety of configurations, e.g., a sheet, bead, or other structure, such as a plate with wells; beads, polymers, particle, a fibrous mesh, hydrogels, porous matrix, a pin, a microarray surface, a chromatography support, and the like. In some instances, the support is selected from the group consisting of a particle, a planar solid substrate, a fibrous mesh, a hydrogel, a porous matrix, a pin, a microarray surface and a chromatography support. The support may be incorporated into a system that it provides for cell isolation assisted by any convenient methods, such as a manually-operated syringe, a centrifuge or an automated liquid handling system. In some cases, the support finds use in an automated liquid handling system for the high throughput isolation of cells, such as a flow cytometer. 
     In some embodiments of the method, the separating step includes applying an external magnetic field to immobilize a magnetic particle. Any convenient magnet may be used as a source of the external magnetic field (e.g., magnetic field gradient). In some cases, the external magnetic field is generated by a magnetic source, e.g. by a permanent magnet or electromagnet. In some cases, immobilizing the magnetic particles means the magnetic particles accumulate near the surface closest to the magnetic field gradient source, i.e. the magnet. 
     The separating may further include one or more optional washing steps to remove unbound material of the sample from the support. Any convenient washing methods may be used, e.g., washing the immobilized support with a biocompatible buffer which preserves the specific binding interaction of the polymeric dye and the specific binding member. Separation and optional washing of unbound material of the sample from the support provides for an enriched population of target cells where undesired cells and material may be removed. 
     In certain embodiments, the method further includes detecting the labeled target. Detecting the labeled target may include exciting the multichromophore with one or more lasers and subsequently detecting fluorescence emission from the polymeric tandem dye using one or more optical detectors. Detection of the labeled target can be performed using any convenient instruments and methods, including but not limited to, flow cytometry, FACS systems, fluorescence microscopy; fluorescence, luminescence, ultraviolet, and/or visible light detection using a plate reader; high performance liquid chromatography (HPLC); and mass spectrometry. When using fluorescently labeled components in the methods and compositions of the present disclosure, it is recognized that different types of fluorescence detection systems can be used to practice the subject methods. In some cases, high throughput screening can be performed, e.g., systems that use 96 well or greater microtiter plates. A variety of methods of performing assays on fluorescent materials can be utilized, such as those methods described in, e.g., Lakowicz, J. R., Principles of Fluorescence Spectroscopy, New York: Plenum Press (1983); Herman, B., Resonance energy transfer microscopy, in: Fluorescence Microscopy of Living Cells in Culture, Part B, Methods in Cell Biology, vol. 30, ed. Taylor, D. L. &amp; Wang, Y.-L., San Diego: Academic Press (1989), pp. 219-243; Turro, N.J., Modern Molecular Photochemistry, Menlo Park: Benjamin/Cummings Publishing Col, Inc. (1978), pp. 296-361. 
     Fluorescence in a sample can be measured using a fluorimeter. In some cases, excitation radiation, from an excitation source having a first wavelength, passes through excitation optics. The excitation optics cause the excitation radiation to excite the sample. In response, fluorescently labeled targets in the sample emit radiation which has a wavelength that is different from the excitation wavelength. Collection optics then collect the emission from the sample. The device can include a temperature controller to maintain the sample at a specific temperature while it is being scanned. In certain instances, a multi-axis translation stage moves a microtiter plate holding a plurality of samples in order to position different wells to be exposed. The multi-axis translation stage, temperature controller, auto-focusing feature, and electronics associated with imaging and data collection can be managed by an appropriately programmed digital computer. The computer also can transform the data collected during the assay into another format for presentation. 
     In some embodiments, the method of evaluating a sample for the presence of a target analyte further includes detecting fluorescence in a flow cytometer. In some embodiments, the method of evaluating a sample for the presence of a target analyte further includes imaging the labeling composition contacted sample using fluorescence microscopy. Fluorescence microscopy imaging can be used to identify a polymeric dye conjugate-target analyte binding complex in the contacted sample to evaluate whether the target analyte is present. Microscopy methods of interest that find use in the subject methods include laser scanning confocal microscopy. 
     Also provided are methods of labeling a target molecule. The subject polymeric dyes, find use in a variety of methods of labeling, separation, detection and/or analysis. In some embodiments, the method includes: contacting the target molecule with a polymeric dye (e.g., as described herein) to produce a labeled target molecule, wherein the polymeric dye includes a conjugation tag that covalently links to the target molecule. In some cases, the polymeric dye further includes a signaling chromophore covalently linked to the multichromophore of the polymeric dye in energy-receiving proximity therewith. In some instances of the method, the polymeric dye member includes a multichromophore according to any one of formulae (I)-(XXII) (e.g., as described herein), where one of G 1  and G 2  is a terminal group and the other of G 1  and G 2  is the conjugation tag. 
     As used herein the term “conjugation tag” refers to a group that includes a chemoselective functional group (e.g., as described herein) that can covalently link with a compatible functional group of a target molecule, after optional activation and/or deprotection. Any convenient conjugation tags may be utilized in the subject polymeric dyes in order to conjugate the dye to a target molecule of interest. In some embodiments, the conjugation tag includes a terminal functional group selected from an amino, a carboxylic acid or a derivative thereof, a thiol, a hydroxyl, a hydrazine, a hydrazide, a azide, an alkyne and a protein reactive group (e.g. amino-reactive, thiol-reactive, hydroxyl-reactive, imidazolyl-reactive or guanidinyl-reactive). 
     Any convenient methods and reagent may be adapted for use in the subject labeling methods in order to covalently link the conjugation tag to the target molecule. Methods of interest for labeling a target, include but are not limited to, those methods and reagents described by Hermanson, Bioconjugate Techniques, Third edition, Academic Press, 2013. The contacting step may be performed in an aqueous solution. In some instances, the conjugation tag includes an amino functional group and the target molecule includes an activated ester functional group, such as a NHS ester or sulfo-NHS ester, or vice versa. In certain instances, the conjugation tag includes a maleimide functional group and the target molecule includes a thiol functional group, or vice versa. In certain instances, the conjugation tag includes an alkyne (e.g., a cyclooctyne group) functional group and the target molecule includes an azide functional group, or vice versa, which can be conjugated via Click chemistry. 
     Any convenient target molecules may be selected for labeling utilizing the subject methods. Target molecules of interest include, but are not limited to, a nucleic acid, such as an RNA, DNA, PNA, CNA, HNA, LNA or ANA molecule, a protein, such as a fusion protein, a modified protein, such as a phosphorylated, glycosylated, ubiquitinated, SUMOylated, or acetylated protein, or an antibody, a peptide, an aggregated biomolecule, a cell, a small molecule, a vitamin and a drug molecule. As used herein, the term “a target protein” refers to all members of the target family, and fragments thereof. The target protein may be any protein of interest, such as a therapeutic or diagnostic target, including but not limited to: hormones, growth factors, receptors, enzymes, cytokines, osteoinductive factors, colony stimulating factors and immunoglobulins. The term “target protein” is intended to include recombinant and synthetic molecules, which can be prepared using any convenient recombinant expression methods or using any convenient synthetic methods, or purchased commercially. In some embodiments, the target molecule is a specific binding member (e.g., as described herein). In certain instances, the specific binding member is an antibody. In some instances, the specific binding member is an antibody fragment or binding derivative thereof. In some case, the antibody fragment or binding derivative thereof is selected from the group consisting of a Fab fragment, a F(ab′) 2  fragment, a scFv, a diabody and a triabody. 
     In some cases, the method includes a separating step where the labeled target molecule is separated from the reaction mixture, e.g., excess reagents or unlabeled target. A variety of methods may be utilized to separate a target from a sample, e.g., via immobilization on a support, precipitation, chromatography, and the like. 
     In some instances, the method further includes detecting and/or analyzing the labeled target molecule. In some instances, the method further includes fluorescently detecting the labeled target molecule. Any convenient methods may be utilized to detect and/or analyze the labeled target molecule in conjunction with the subject methods and compositions. Methods of analyzing a target of interest that find use in the subject methods, include but are not limited to, flow cytometry, fluorescence microscopy, in-situ hybridization, enzyme-linked immunosorbent assays (ELISAs), western blot analysis, magnetic cell separation assays and fluorochrome purification chromatography. Detection methods of interest include but are not limited to fluorescence spectroscopy, fluorescence microscopy, nucleic acid sequencing, fluorescence in-situ hybridization (FISH), protein mass spectroscopy, flow cytometry, and the like. 
     Detection may be achieved directly via the polymeric dye or polymeric tandem dye, or indirectly by a secondary detection system. The latter may be based on any one or a combination of several different principles including, but not limited to, antibody labeled anti-species antibody and other forms of immunological or non-immunological bridging and signal amplification systems (e.g., biotin-streptavidin technology, protein-A and protein-G mediated technology, or nucleic acid probe/anti-nucleic acid probes, and the like). Suitable reporter molecules may be those known in the field of immunocytochemistry, molecular biology, light, fluorescence, and electron microscopy, cell immunophenotyping, cell sorting, flow cytometry, cell visualization, detection, enumeration, and/or signal output quantification. More than one antibody of specific and/or non-specific nature might be labeled and used simultaneously or sequentially to enhance target detection, identification, and/or analysis. 
     Systems 
     Aspects of the invention further include systems for use in practicing the subject methods and compositions. A sample analysis system can include sample field of view or a flow channel loaded with a sample and a labeled specific binding member. In some embodiments, the system is a flow cytometric system including: a flow cytometer including a flow path; a composition in the flow path, wherein the composition includes: a sample; and a labeled specific binding member (e.g., as described herein). In some embodiments, the system for analyzing a sample is a fluorescence microscopy system, including: a fluorescence microscope comprising a sample field of view; and a composition disposed in the sample field of view, wherein the composition comprises a sample; and a labeled specific binding member (e.g., as described herein). 
     In some instances of the systems, the labeled specific binding member includes: a water solvated light harvesting multichromophore (e.g., as described herein) and a specific binding member that specifically binds a target analyte covalently linked to the multichromophore. In some cases, the labeled specific binding member further comprises a signaling chromophore covalently linked to the multichromophore of the polymeric dye in energy-receiving proximity therewith. In some instances of the subject systems, the labeled specific binding member, the multichromophore is described by any one of formulae (I) (XXII) (e.g., as described herein), wherein: G 1  and G 2  are each independently selected from the group consisting of a terminal group, a π conjugated segment, a linker and a linked specific binding member, wherein at least one of G 1  and G 2  is a linked specific binding member. 
     In certain embodiments of the systems, the composition further includes a second specific binding member that is support bound and specifically binds the target analyte. In some cases, the support includes a magnetic particle. As such, in certain instances, the system may also include a controllable external paramagnetic field configured for application to an assay region of the flow channel. 
     The sample may include a cell. In some instances, the sample is a cell-containing biological sample. In some instances, the sample includes a labeled specific binding member specifically bound to a target cell. In certain instances, the target analyte that is specifically bound by the specific binding member is a cell surface marker of the cell. In certain cases, the cell surface marker is selected from the group consisting of a cell receptor and a cell surface antigen. 
     In certain aspects, the system may also include a light source configured to direct light to an assay region of the flow channel or sample field of view. The system may include a detector configured to receive a signal from an assay region of the flow channel or a sample field of view, wherein the signal is provided by the fluorescent composition. Optionally further, the sample analysis system may include one or more additional detectors and/or light sources for the detection of one or more additional signals. 
     In certain aspects, the system may further include computer-based systems configured to detect the presence of the fluorescent signal. A “computer-based system” refers to the hardware means, software means, and data storage means used to analyze the information of the present invention. The minimum hardware of the computer-based systems of the present invention includes a central processing unit (CPU), input means, output means, and data storage means. A skilled artisan can readily appreciate that any one of the currently available computer-based system are suitable for use in the subject systems. The data storage means may include any manufacture including a recording of the present information as described above, or a memory access means that can access such a manufacture. 
     To “record” data, programming or other information on a computer readable medium refers to a process for storing information, using any such methods as known in the art. Any convenient data storage structure may be chosen, based on the means used to access the stored information. A variety of data processor programs and formats can be used for storage, e.g., word processing text file, database format, etc. 
     A “processor” references any hardware and/or software combination that will perform the functions required of it. For example, any processor herein may be a programmable digital microprocessor such as available in the form of an electronic controller, mainframe, server or personal computer (desktop or portable). Where the processor is programmable, suitable programming can be communicated from a remote location to the processor, or previously saved in a computer program product (such as a portable or fixed computer readable storage medium, whether magnetic, optical or solid state device based). For example, a magnetic medium or optical disk may carry the programming, and can be read by a suitable reader communicating with each processor at its corresponding station. 
     In addition to the sensor device and signal processing module, e.g., as described above, systems of the invention may include a number of additional components, such as data output devices, e.g., monitors and/or speakers, data input devices, e.g., interface ports, keyboards, etc., fluid handling components, power sources, etc. 
     In certain aspects, the system includes a flow cytometer. Flow cytometers of interest include, but are not limited, to those devices described in U.S. Pat. Nos. 4,704,891; 4,727,029; 4,745,285; 4,867,908; 5,342,790; 5,620,842; 5,627,037; 5,701,012; 5,895,922; and 6,287,791; the disclosures of which are herein incorporated by reference. 
     Other systems may find use in practicing the subject methods. In certain aspects, the system may be a fluorimeter or microscope loaded with a sample having a fluorescent composition of any of the embodiments discussed herein. The fluorimeter or microscope may include a light source configured to direct light to the assay region of the flow channel or sample field of view. The fluorimeter or microscope may also include a detector configured to receive a signal from an assay region of the flow channel or field of view, wherein the signal is provided by the fluorescent composition. 
     Kits 
     Aspects of the invention further include kits for use in practicing the subject methods and compositions. The compositions of the invention can be included as reagents in kits either as starting materials or provided for use in, for example, the methodologies described above. 
     A kit can include a polymeric dye including a water solvated light harvesting multichromophore (e.g., as described herein) and a container. Any convenient containers can be utilized, such as tubes, bottles, or wells in a multi-well strip or plate, a box, a bag, an insulated container, and the like. The subject kits can further include one or more components selected from a polymeric tandem dye, a fluorophore, a specific binding member, a specific binding member conjugate, a support bound specific binding member, a cell, a support, a biocompatible aqueous elution buffer, and instructions for use. In some embodiments of the kit, the multichromophore is covalently linked to a specific binding member. In some instances, the specific binding member is an antibody. 
     In certain instances, the specific binding member is an antibody fragment or binding derivative thereof. In certain cases, the antibody fragment or binding derivative thereof is selected from the group consisting of a Fab fragment, a F(ab′) 2  fragment, a scFv, a diabody and a triabody. 
     In certain embodiments, the kit finds use in evaluating a sample for the presence of a target analyte, such as an intracellular target. As such, in some instances, the kit includes one or more components suitable for lysing cells. The one or more additional components of the kit may be provided in separate containers (e.g., separate tubes, bottles, or wells in a multi-well strip or plate). 
     In certain aspects, the kit further includes reagents for performing a flow cytometric assay. Reagents of interest include, but are not limited to, buffers for reconstitution and dilution, buffers for contacting a cell sample the multichromophore, wash buffers, control cells, control beads, fluorescent beads for flow cytometer calibration and combinations thereof. The kit may also include one or more cell fixing reagents such as paraformaldehyde, glutaraldehyde, methanol, acetone, formalin, or any combinations or buffers thereof. Further, the kit may include a cell permeabilizing reagent, such as methanol, acetone or a detergent (e.g., triton, NP-40, saponin, tween 20, digitonin, leucoperm, or any combinations or buffers thereof. Other protein transport inhibitors, cell fixing reagents and cell permeabilizing reagents familiar to the skilled artisan are within the scope of the subject kits. 
     The compositions of the kit may be provided in a liquid composition, such as any suitable buffer. Alternatively, the compositions of the kit may be provided in a dry composition (e.g., may be lyophilized), and the kit may optionally include one or more buffers for reconstituting the dry composition. In certain aspects, the kit may include aliquots of the compositions provided in separate containers (e.g., separate tubes, bottles, or wells in a multi-well strip or plate). 
     In addition, one or more components may be combined into a single container, e.g., a glass or plastic vial, tube or bottle. In certain instances, the kit may further include a container (e.g., such as a box, a bag, an insulated container, a bottle, tube, etc.) in which all of the components (and their separate containers) are present. The kit may further include packaging that is separate from or attached to the kit container and upon which is printed information about the kit, the components of the and/or instructions for use of the kit. 
     In addition to the above components, the subject kits may further include instructions for practicing the subject methods. These instructions may be present in the subject kits in a variety of forms, one or more of which may be present in the kit. One form in which these instructions may be present is as printed information on a suitable medium or substrate, e.g., a piece or pieces of paper on which the information is printed, in the packaging of the kit, in a package insert, etc. Yet another means would be a computer readable medium, e.g., diskette, CD, DVD, portable flash drive, etc., on which the information has been recorded. Yet another means that may be present is a website address which may be used via the Internet to access the information at a removed site. Any convenient means may be present in the kits. 
     Utility 
     The polymeric dyes, compositions, methods and systems as described herein may find use in a variety of applications, including diagnostic and research applications, in which the labeling, detection and/or analysis of a target of interest is desirable. Such applications include methodologies such as cytometry, microscopy, immunoassays (e.g. competitive or non-competitive), assessment of a free analyte, assessment of receptor bound ligand, and so forth. The compositions, system and methods described herein may be useful in analysis of any of a number of samples, including but not limited to, biological fluids, cell culture samples, and tissue samples. In certain aspects, the compositions, system and methods described herein may find use in methods where analytes are detected in a sample, if present, using fluorescent labels, such as in fluorescent activated cell sorting or analysis, immunoassays, immunostaining, and the like. In certain instances, the compositions and methods find use in applications where the evaluation of a sample for the presence of a target analyte is of interest. 
     In some cases, the methods and compositions find use in any assay format where the detection and/or analysis of a target from a sample is of interest, including but not limited to, flow cytometry, fluorescence microscopy, in-situ hybridization, enzyme-linked immunosorbent assays (ELISAs), western blot analysis, magnetic cell separation assays and fluorochrome purification chromatography. In certain instances, the methods and compositions find use in any application where the fluorescent labeling of a target molecule is of interest. The subject compositions may be adapted for use in any convenient applications where pairs of specific binding members find use, such as biotin-streptavidin and hapten-anti-hapten antibody. 
     EXAMPLES 
     Example 1: Synthesis of an Ethynylene-Linked Polymer 
     Polymeric dyes having a range of co-monomers connected via ethynylene linkages can be synthesized using a Sonogashira coupling route that utilizes a Pd catalyst, an aryl halide and a terminal ethynylene group to form the polymer backbone. A range of polymers were synthesized with a common 1, 4-linked phenyl co-monomer and are shown in  FIG.  2   . The extensive use of water solubilizing side chains provides increased water solubility of the resulting polymer. The installation of a functional group at the terminal position of the polymer provides for bioconjugation and other post-synthesis modifications. 
     The resulting polymers exhibit a range of absorption wavelengths from 400-600 nm and can be designed to have maximal absorption outside this range as well. One means of tuning the absorption wavelength amongst the group is by changing the co-monomers used with the 1,4-substituted phenyl group. By changing the co-monomer, a range of absorption and emission wavelengths can be achieved. 
     There are differences in quantum yield as well that are unique to the co-monomers and the degree of solubilizing groups attached to them. Another feature of this class of structure is that a new related set of shorter wavelength absorption maxima can be reached by changing the position of substituents on the phenyl co-monomer for the polymerization. A 1,3-linkage results in shorter wavelength absorption maxima. 
     A set of structures was synthesized using this principle and are shown in  FIG.  3   . Changing to the 1,3-substitution also helps with solubility by providing more degrees of freedom in the overall backbone by bond rotation. These structures have absorption in the range from 350 nm to 550 nm. 
     Using the described polymeric backbones, internal linking sites can be randomly inserted at a known feed ratio to provide sites to attach a signaling chromophore (“Dye”,  FIG.  4   ). The internal linking site has a functional group that is chemically orthogonal to the terminal linker site, providing for attachment at specific sites by controlling the chemistry. The signaling chromophore acts as an acceptor for energy transfer from the polymer which acts as a donor. This provides for a polymer that absorbs at the wavelength attributable to the polymer backbone but emission corresponding to the acceptor dye. This tandem scheme provides for a single polymeric core with a single absorption that can provide multiple emission wavelengths using different covalently linked dyes. The multiple emission wavelengths that are possible provide for multiple parameters from a single excitation source, expanding options for improving the volume and quality of information from a flow cytometry experiment. 
     Examples of this tandem scheme are shown in  FIG.  1   . The structure 1 shown is a tandem core polymer prepared with ethynylene linkages. The absorption and emission spectra of the core polymeric dye and two polymeric tandem dyes made from that core are shown in the spectra. For the red-emitter, the Dyomics dye DY-633 was attached and for the NIR dye, Dyomics dye DY-752 was attached. Comparing the core to the two tandems shows that by using the internal linking site to attach signalling chromophores, a range of emission wavelengths can be achieved that are the result of the attached dye or lack of attached dye with all structures exhibiting the same maximal absorption. 
     Other structures were generated using the Sonogashira coupling to form ethynylene linkages between monomers that are shown in  FIG.  5   . In place of the phenyl group with four fold solubilizing side chains, structures with less substitution are shown. Also, alternatives to the phenyl group as a co-monomer are demonstrated such as perylene, fluorene, carbazole, and binapthol co-monomers. Through such variations in the structure, different absorption maximum wavelengths can be achieved. 
     Example 2: Synthesis of an Vinylene-Linked Polymer 
     Using a similar procedure to that described above for ethynylene linked Polymeric dye structures were prepared that link co-monomers using a vinylene linkage as shown in  FIG.  6   . The wavelengths achieved with this linkage can result in polymers with longer maximal absorption wavelengths than their ethynylene linked counterparts. This provides another strategy to tune the absorption of the polymer structure. 
     Example 3: Synthesis of a Covalently-Linked Polymer Via Suzuki Coupling 
     Using Suzuki chemistry, phenyl-phenyl bonds or phenyl-aryl bonds between co-monomers can be created, as shown in  FIG.  7   . These structures can absorb at wavelengths shorter than their ethynylene or vinylene linked counterparts with similar co-monomer structures and add to the repertoire with which optical properties can be tuned. Finally, homo-coupling of polycyclic and heteropolycyclic systems can be used to create systems with unique absorption and emission characteristics. Similar to polyfluorene structures, changes in the number of locked rings or introducing heteroatoms can lead to desirable tuning of absorption and emission wavelength as well as quantum yield and solubility. 
     Notwithstanding the appended claims, the disclosure set forth herein is also defined by the following clauses: 
     Clause 1. A water solvated light harvesting multichromophore comprising a conjugated segment having the structure of formula (I): 
                         
wherein: each L is independently a covalent bond, a vinylene group or an ethynylene group; M 1  and M 2  are independently an aryl co-monomer or heteroaryl co-monomer; each * is a site for covalent attachment to the unsaturated backbone of a conjugated polymer; and n is an integer from 1 to 100,000.
 
Clause 2. The water solvated light harvesting multichromophore according to clause 1, wherein each M 1  is a substituted phenyl co-monomer.
 
Clause 3. The water solvated light harvesting multichromophore according to clause 1, wherein the conjugated segment has the structure of formula (II):
 
                         
wherein: each W is independently selected from an alkyl, a substituted alkyl, an aralkyl, a substituted aralkyl, an aryl, a substituted aryl, a heteroaryl, a substituted heteraryl, a PEG or modified PEG group and a water soluble group (WSG); and q is 1, 2, 3 or 4.
 
Clause 4. The water solvated light harvesting multichromophore according to clause Clause 3, wherein the conjugated segment has the structure of formula (III):
 
                         
Clause 5. The water solvated light harvesting multichromophore according to clause 3, wherein the conjugated segment has the structure of formula (IV):
 
                         
Clause 6. The water solvated light harvesting multichromophore according to any one of clauses 2-5, wherein M 2  is substituted with one or more W groups each independently selected from an alkyl, a substituted alkyl, an aralkyl, a substituted aralkyl, an aryl, a substituted aryl, a heteroaryl, a substituted heteraryl, a PEG or modified PEG group and a WSG.
 
Clause 7. The water solvated light harvesting multichromophore according to any one of clauses 3-6, wherein:
 
     q is 2 or 3; and 
     each W is independently selected from:
         —Y 1 —(CH 2 CH 2 O) r —R′;   —Y 1 —O—CH[(CH 2 ) q —O—(CH 2 CH 2 O) r —R′] 2 ; and   —Y 1 —CH 2 -Ph(Y 1 —(CH 2 CH 2 O) r —R) s ;   wherein Y 1  is selected from a covalent bond, —O—, —CONH—, —NHCO— and —(CH 2 ) q —O—, q and r are each independently an integer from 1 to 50, s is 1, 2 or 3 and each R′ is H, alkyl or substituted alkyl.
 
Clause 8. The water solvated light harvesting multichromophore according to any one of clauses 1-7, wherein n is 5 or more.
 
Clause 9. The water solvated light harvesting multichromophore according to any one of clauses 1-8, wherein the conjugated segment is 25 mol % or more of the multichromophore.
 
Clause 10. The water solvated light harvesting multichromophore according to clause 1, wherein the multichromophore has the structure of formula (V):
       

                         
wherein:
 
     M 1 , M 2 , M 3  and M 4  are independently an aryl co-monomer or heteroaryl co-monomer; 
     each L is an ethynylene linking unit; 
     each n is independently an integer from 1 to 10,000; 
     each m is independently 0 or an integer from 1 to 10,000; 
     p is an integer from 1 to 100,000; and 
     G 1  and G 2  are each independently selected from a terminal group, a t conjugated segment, a linker and a linked specific binding member. 
     Clause 11. The water solvated light harvesting multichromophore according to clause 10, wherein the multichromophore has the structure of formula (VI): 
     
       
         
         
             
             
         
       
     
     wherein n is an integer from 1 to 100,000. 
     Clause 12. The water solvated light harvesting multichromophore according to clause 10, wherein the multichromophore has the structure of formula (VII): 
                         
wherein: Z 1  is a chemoselective functional group or a linked signaling chromophore; and T 1  is a linker.
 
Clause 13. The water solvated light harvesting multichromophore according to clause 10, wherein M 1  and M 3  are the same aryl or heteroaryl co-monomer.
 
Clause 14. The water solvated light harvesting multichromophore according to clause 10, wherein the multichromophore has the structure of formula (VIII):
 
                         
wherein: Z 1  is a chemoselective functional group or a linked signaling chromophore; and T 1  is a linker.
 
Clause 15. The water solvated light harvesting multichromophore according to any one of clauses 10-14, comprising the structure of formula (III):
 
                         
wherein: each W is independently selected from an alkyl, a substituted alkyl, an aralkyl, a substituted aralkyl, an aryl, a substituted aryl, a heteroaryl, a substituted heteroaryl, a PEG or modified PEG group and a WSG; and q is 1, 2, 3 or 4.
 
Clause 16. The water solvated light harvesting multichromophore according to any one of clauses 10-14, comprising the structure of formula (IV):
 
                         
wherein: each W is independently selected from an alkyl, a substituted alkyl, an aralkyl, a substituted aralkyl, an aryl, a substituted aryl, a heteroaryl, a substituted heteraryl, a PEG or modified PEG group and a WSG; and q is 1, 2, 3 or 4.
 
Clause 17. The water solvated light harvesting multichromophore according to any one of clauses 12-16, wherein Z 1  is a chemoselective functional group.
 
Clause 18. The water solvated light harvesting multichromophore according to any one of clauses 12-16, wherein Z 1  is a linked signaling chromophore.
 
Clause 19. The water solvated light harvesting multichromophore according to clause 10, wherein the multichromophore has the structure of formula (IX):
 
                         
wherein: each W is independently selected from an alkyl, a substituted alkyl, an aralkyl, a substituted aralkyl, an aryl, a substituted aryl, a heteroaryl, a substituted heteraryl, a PEG or modified PEG group and a WSG; and q is 1, 2, 3 or 4.
 
Clause 20. The water solvated light harvesting multichromophore according to clause 19, wherein the phenyl co-monomers (M 1  and M 3 ) are 1,4-linked.
 
Clause 21. The water solvated light harvesting multichromophore according to clause 20, wherein the multichromophore has the structure of formula (X):
 
                         
wherein: W 1  and W 2  are as defined for W; Z 2  is a chemoselective functional group or a linked specific binding member; and T 2  is a linker.
 
Clause 22. The water solvated light harvesting multichromophore according to any one of clauses 12, 13 and 20, wherein the multichromophore has the structure of formula (XI):
 
                         
wherein: W 1  and W 2  are as defined for W; Z 1  is a chemoselective functional group or a linked signaling chromophore; and T 1  is a linker.
 
Clause 23. The water solvated light harvesting multichromophore according to clause 20, wherein the multichromophore has the structure of formula (XII):
 
                         
wherein: W 1 -W 3  are as defined for W; Z 2  is a chemoselective functional group or a linked specific binding member; T 2  and T 3  are each independently a linker; and Dye is a signaling chromophore.
 
Clause 24. The water solvated light harvesting multichromophore according to clause 19, wherein the phenyl co-monomers (M 1  and M 3 ) are 1,3-linked.
 
Clause 25. The water solvated light harvesting multichromophore according to clause 24, wherein the multichromophore has the structure of formula (XIII):
 
                         
wherein: W 3 , W 4  and W 5  are as defined for W.
 
Clause 26. The water solvated light harvesting multichromophore according to clause 24, wherein the multichromophore has the structure of formula (XIV):
 
                         
wherein: W 3  and W 5  are as defined for W; Z 2  is a chemoselective functional group or a linked specific binding member; and T 2  is a linker.
 
Clause 27. The water solvated light harvesting multichromophore according to clause 19, wherein the multichromophore has the structure of formula (XV):
 
                         
wherein: W 3 , W 4  and W 5  are as defined for W; Z 1  is a chemoselective functional group or a linked signaling chromophore; and T 1  is a linker.
 
Clause 28. The water solvated light harvesting multichromophore according to clause 27, wherein the conjugated segment has the structure of formula (XVI):
 
                         
wherein W 6  is as defined for W; Z 2  is a chemoselective functional group or a linked specific binding member; T 2  and T 3  are each independently a linker; and Dye is a signaling chromophore.
 
Clause 29. The water solvated light harvesting multichromophore according to clause 1, wherein the conjugated segment has the structure of formula (V):
 
                         
wherein:
 
     M 1 , M 2 , M 3  and M 4  are independently an aryl or heteroaryl co-monomer; 
     each L is a vinylene group; 
     each n is independently an integer from 1 to 10,000; 
     each m is 0 or independently an integer from 1 to 10,000; 
     p is an integer from 1 to 100,000; and 
     G 1  and G 2  are each independently selected from a terminal group, a t conjugated segment, a linker and a linked specific binding member. 
     Clause 30. The water solvated light harvesting multichromophore according to clause 29, wherein the multichromophore has the structure of formula (VII): 
                         
wherein: Z 1  is a chemoselective functional group or a linked signaling chromophore; and T 1  is a linker.
 
Clause 31. The water solvated light harvesting multichromophore according to clause 29 or 30, wherein the conjugated segment comprises the structure of formula (XVII):
 
                         
Clause 32. The water solvated light harvesting multichromophore according to clause 31, wherein the conjugated segment comprises the structure of formula (XVIII):
 
                         
Clause 33. The water solvated light harvesting multichromophore according to any one of clauses 29-32, wherein the conjugated segment comprises the structure of formula (XIX) or (XX):
 
                         
wherein W 1  and W 2  are as defined for W.
 
Clause 34. The water solvated light harvesting multichromophore according to clause 1, wherein the conjugated segment has the structure of formula (V):
 
                         
wherein:
 
     M 1 , M 2 , M 3  and M 4  are independently an aryl or heteroaryl co-monomer; 
     at least two L are covalent bonds; 
     each n is independently an integer from 1 to 10,000; 
     each m is 0 or independently an integer from 1 to 10,000; 
     p is an integer from 1 to 100,000; and 
     G 1  and G 2  are each independently selected from a terminal group, a t conjugated segment, a linker and a linked specific binding member. 
     Clause 35. The water solvated light harvesting multichromophore according to clause 34, wherein the multichromophore has the structure of formula (VII): 
                         
wherein: Z 1  is a chemoselective functional group or a linked signaling chromophore; and T 1  is a linker.
 
Clause 36. The water solvated light harvesting multichromophore according to clause 34 or 35, wherein the conjugated segment comprises the structure of formula (XXI):
 
                         
wherein W 11  and W 12  are as defined for W.
 
Clause 37. The water solvated light harvesting multichromophore according to clause 36, wherein the conjugated segment comprises the structure of formula (XXII):
 
                         
wherein W 13  is as defined for W.
 
Clause 38. The water solvated light harvesting multichromophore according to any one of clauses 2-37, wherein each W and each W 1 -W 13  are independently selected from one of the following structures:
 
                                           
wherein: T 5  is an optional linker; and each s is an integer from 1 to 50.
 
Clause 39. The water solvated light harvesting multichromophore according to any one of clauses 1-38, wherein M 2 , M 3  and M 4  are independently selected from one of formulae (XXIII)-(XXVI):
 
                         
wherein
 
     Cy 2-7  is an aryl or heteroaryl group comprising 2 to 7 fused and/or unfused rings; 
     Y 2 , Y 3  and Y 4  are independently selected from —CR 3 —, NR 3 , N, O, S and —C(═O)— and together form a 5 or 6 membered fused aryl or heteraryl ring; 
     each R 3  is one or more ring substituents independently selected from H, halogen, alkyl, substituted alkyl, aryl, substituted aryl, heteroaryl, substituted heteroaryl, acyl, substituted acyl, sulfonic acid, cyano, alkoxy substituted alkoxy and -T 1 -Z 1 ; 
     R 1  and R 2  are independently selected from H, halogen, alkyl, substituted alkyl, aryl, substituted aryl, heteroaryl, substituted heteroaryl, acyl, substituted acyl, sulfonic acid, cyano, alkoxy, substituted alkoxy and -T 1 -Z 1 , or R 1  and R 2  together form a 5- or 6-membered fused aryl, heteroaryl, cycloalkyl or heterocycle ring which can be optionally substituted; 
     Y 5  is N or CR 5  and Y 7  is N or CR 7 ; 
     R 4 -R 7  are independently selected from H, halogen, alkyl, substituted alkyl, aryl, substituted aryl, heteroaryl, substituted heteroaryl, acyl, substituted acyl, sulfonic acid, cyano, alkoxy, substituted alkoxy and -T 1 -Z 1 ; 
     Z 1  is a chemoselective functional group or a linked signaling chromophore; and 
     T 1  is a linker. 
     Clause 40. The water solvated light harvesting multichromophore according to clause 39, wherein M 2 , M 3  and M 4  are independently selected from one of the following structures (a) to (x): 
                                                                               
wherein:
 
     Y 8  is C(R 3 ) 2 , —C(R 3 ) 2 C(R 3 ) 2 —, NR 3  or Si(R 3 ) 2 ; 
     X is S or O; 
     each R 3  is independently H, a water solubilizing group (e.g., as described herein), amino, substituted amino, halogen, cyano, alkyl, substituted alkyl, aryl, substituted aryl, heteroaryl, substituted heteroaryl, acyl, substituted acyl, sulfonic acid, cyano, alkoxy, substituted alkoxy and -T 1 -Z 1 ; 
     Z 1  is a chemoselective functional group or a linked signaling chromophore; and 
     T 1  is a linker. 
     Clause 41. The water solvated light harvesting multichromophore according to any one of clauses 39-40, wherein M 2 , M 3  and M 4  are independently selected from one of the following structures (ba) to (cd): 
                                                                                                 
wherein:
 
     Y 9  is C(R 4 ) 2 , —C(R 4 ) 2 C(R 4 ) 2 — or Si(R 4 ) 2 ; 
     each R 4  is independently H, a water solubilizing group (e.g., as described herein), alkyl, substituted alkyl, aryl, substituted aryl, heteroaryl, substituted heteroaryl, acyl, substituted acyl, sulfonic acid, cyano, alkoxy, substituted alkoxy and -T 1 -Z 1 ; and 
     R 1  and R 2  are independently selected from H, halogen, alkyl, substituted alkyl, aryl, substituted aryl, heteroaryl, substituted heteroaryl, acyl, substituted acyl, sulfonic acid, cyano, alkoxy, substituted alkoxy and -T 1 -Z 1 , or R 1  and R 2  together form a 5- or 6-membered fused aryl or heteroaryl ring which can be optionally substituted. 
     Clause 42. The water solvated light harvesting multichromophore according to any one of clauses 40-41, wherein each R 3  and each R 4  are independently selected from one of the following structures: 
                                           
wherein:
 
     T 5  is an optional linker; and 
     each s is an integer from 1 to 50. 
     Clause 43. The water solvated light harvesting multichromophore according to any one of clauses 39-42, wherein M 2 , M 3  and M 4  are independently selected from one of the following structures: 
                                                                                                                   
Clause 44. The water solvated light harvesting multichromophore according to any one of clauses 12, 14, 22, 27, 28, 30 and 35, wherein the multichromophore comprises a co-monomer linked to a signaling chromophore having the one of the following structures:
 
                         
wherein: WSG is an optional water soluble group; T 2  is a linker; and Dye is the signaling chromophore.
 
Clause 45. A polymeric tandem dye comprising:
 
     a water soluble light harvesting multichromophore comprising a conjugated segment having the structure of formula (I): 
     
       
         
         
             
             
         
       
     
     wherein:
         each L is independently a conjugated backbone linking unit selected from a covalent bond, a vinylene group and an ethynylene group;   M 1  and M 2  are independently an aryl co-monomer or heteroaryl co-monomer;   each * is a site for covalent attachment to the unsaturated backbone of a conjugated polymer; and   n is an integer from 1 to 100,000; and       

     a signaling chromophore covalently linked to the multichromophore in energy-receiving proximity therewith. 
     Clause 46. The polymeric tandem dye according to clause 45, wherein the multichromophore has an absorption maximum wavelength from 300 nm to 600 nm. 
     Clause 47. The polymeric tandem dye according to clause 45, wherein the multichromophore has an absorption maximum wavelength from 300 nm to 400 nm. 
     Clause 48. The polymeric tandem dye according to Clause 45, wherein the signaling chromophore emission has a quantum yield of 0.1 or more. 
     Clause 49. The polymeric tandem dye according to Clause 45, wherein the signaling chromophore emission has a brightness of 50 mM −1  cm −1  or more. 
     Clause 50. The polymeric tandem dye according to any one of Clauses 45-49, wherein the multichromophore is substituted with non-ionic side groups capable of imparting solubility in water in excess of 10 mg/mL. 
     Clause 51. The polymeric tandem dye according to any one of Clauses 45-50, wherein the signaling chromophore is a fluorophore. 
     Clause 52. The polymeric tandem dye according to any one of Clauses 45-51, wherein the signaling chromophore is a quencher. 
     Clause 53. The polymeric tandem dye according to any one of Clauses 45-52, wherein the signaling chromophore is selected from a rhodamine, a coumarin, a xanthene, a cyanine, a polymethine, a pyrene, a dipyrromethene borondifluoride, a napthalimide, a phycobiliprotein, a peridinum chlorophyll protein, conjugates thereof, and combinations thereof.
 
Clause 54. The polymeric tandem dye according to any one of Clauses 45-51 and 53, wherein the signaling chromophore is selected from fluorescein, 6-FAM, rhodamine, Texas Red, California Red, iFluor594, tetramethylrhodamine, a carboxyrhodamine, carboxyrhodamine 6G, carboxyrhodol, carboxyrhodamine 110, Cascade Blue, Cascade Yellow, coumarin, Cy2®, Cy3®, Cy3.5®, Cy5®, Cy5.5®, Cy7®, Cy-Chrome, DyLight 350, DyLight 405, DyLight 488, DyLight 549, DyLight 594, DyLight 633, DyLight 649, DyLight 680, DyLight 750, DyLight 800, phycoerythrin, PerCP (peridinin chlorophyll-a Protein), PerCP-Cy5.5, JOE (6-carboxy-4′,5′-dichloro-2′,7′-dimethoxyfluorescein), NED, ROX (5-(and -6)-carboxy-X-rhodamine), HEX, Lucifer Yellow, Marina Blue, Oregon Green 488, Oregon Green 500, Oregon Green 514, Alexa Fluor® 350, Alexa Fluor® 430, Alexa Fluor® 488, Alexa Fluor® 532, Alexa Fluor® 546, Alexa Fluor® 568, Alexa Fluor® 594, Alexa Fluor® 633, Alexa Fluor® 647, Alexa Fluor® 660, Alexa Fluor® 680, 7-amino-4-methylcoumarin-3-acetic acid, BODIPY® FL, BODIPY® FL-Br2, BODIPY® 530/550, BODIPY® 558/568, BODIPY® 564/570, BODIPY® 576/589, BODIPY® 581/591, BODIPY® 630/650, BODIPY® 650/665, BODIPY® R6G, BODIPY® TMR, BODIPY® TR, conjugates thereof and combinations thereof.
 
Clause 55. The polymeric tandem dye according to any one of Clauses 45 to 54, wherein: the signaling chromophore is linked to a co-monomer comprising [5%] to [50%] by molarity of the multichromophore; and the multichromophore is a conjugated polymer comprising 5 or more repeat units.
 
Clause 56. The polymeric tandem dye according to any one of Clauses 45 to 51 and 53-55, wherein the signaling chromophore emission is 1.5-fold greater or more when excited by the multichromophore as compared to direct excitation of the signaling chromophore with incident light.
 
Clause 57. The polymeric tandem dye according to any one of Clauses 45-56, wherein the multichromophore comprises a terminal group -L 3 -Z where L 3  is a linker and Z is a specific binding member.
 
Clause 58. The polymeric tandem dye according to Clause 57, wherein the linker is selected from the group consisting of an alkyl, a substituted alkyl, an alkyl-amido, an alkyl-amido-alkyl and a PEG moiety.
 
Clause 59. The polymeric tandem dye according to Clause 58, wherein -L 3 -Z is described by the following structure:
 
                         
wherein: q is 0 or an integer from 1-12; and Z is the specific binding member.
 
Clause 60. The polymeric tandem dye according to any one of Clauses 57-59, wherein Z is a biomolecule.
 
Clause 61. The polymeric tandem dye according to any one of Clauses 57-60, wherein Z is an antibody.
 
Clause 62. The polymeric tandem dye according to any one of Clauses 57-60, wherein Z is an antibody fragment or binding derivative thereof.
 
Clause 63. The polymeric tandem dye according to Clause 62, wherein the antibody fragment or binding derivative thereof is selected from the group consisting of a Fab fragment, a F(ab′) 2  fragment, a scFv, a diabody and a triabody.
 
Clause 64. A labeled specific binding member, comprising:
 
     a water soluble light harvesting multichromophore comprising a conjugated segment having the structure of formula (I): 
     
       
         
         
             
             
         
       
     
     wherein:
         each L is independently a conjugated backbone linking unit selected from a covalent bond, a vinylene group and an ethynylene group;   M 1  and M 2  are independently an aryl co-monomer or heteroaryl co-monomer;   each * is a site for covalent attachment to the unsaturated backbone of a conjugated polymer   n is an integer from 1 to 100,000; and       

     a specific binding member covalently linked to the multichromophore. 
     Clause 65. The labeled specific binding member according to Clause 64, further comprising a signaling chromophore covalently linked to the multichromophore in energy-receiving proximity therewith. 
     Clause 66. The labeled specific binding member according to any one of Clauses 64-65, wherein the specific binding member is an antibody. 
     Clause 67. The labeled specific binding member according to any one of Clauses 64-66, wherein the specific binding member is an antibody fragment or binding derivative thereof. 
     Clause 68. The labeled specific binding member according to Clause 67, wherein the antibody fragment or binding derivative thereof is selected from the group consisting of a Fab fragment, a F(ab′) 2  fragment, a scFv, a diabody and a triabody. 
     Clause 69. The labeled specific binding member according to Clause 65, wherein the signaling chromophore is selected from a rhodamine, a coumarin, a xanthene, a cyanine, a polymethine, a pyrene, a dipyrromethene borondifluoride, a napthalimide, a phycobiliprotein, a peridinum chlorophyll protein, conjugates thereof, and combinations thereof.
 
Clause 70. A method of evaluating a sample for the presence of a target analyte, the method comprising:
 
     (a) contacting the sample with a polymeric dye conjugate that specifically binds the target analyte to produce a labeling composition contacted sample, wherein the polymeric dye conjugate comprises:
         (i) a water soluble light harvesting multichromophore comprising a conjugated segment having the structure of formula (I):       

     
       
         
         
             
             
         
       
         
         
           
             wherein:
           each L is independently a conjugated backbone linking unit selected from a covalent bond, a vinylene group and an ethynylene group;   M 1  and M 2  are independently an aryl co-monomer or heteroaryl co-monomer;   each * is a site for covalent attachment to the unsaturated backbone of a conjugated polymer   n is an integer from 1 to 100,000; and   
         
             (ii) a specific binding member; and 
           
         
       
    
     (b) assaying the labeling composition contacted sample for the presence of a polymeric dye conjugate-target analyte binding complex to evaluate whether the target analyte is present in the sample. 
     Clause 71. The method according to Clause 70, wherein the polymeric dye conjugate further comprises a signaling chromophore covalently linked to the multichromophore in energy-receiving proximity therewith. 
     Clause 72. The method according to any one of Clauses 70-71, further comprising contacting the sample with a second specific binding member that is support bound and specifically binds the target analyte. 
     Clause 73. The method according to Clause 72, wherein the support comprises a magnetic particle. 
     Clause 74. The method according to any one of Clauses 70-73, wherein the target analyte is associated with a cell. 
     Clause 75. The method according to Clause 74, wherein the target analyte is a cell surface marker of the cell. 
     Clause 76. The method according to Clause 75, wherein the cell surface marker is selected from the group consisting of a cell receptor and a cell surface antigen. 
     Clause 77. The method according to Clause 74, wherein the target analyte is an intracellular target, and the method further comprises lysing the cell. 
     Clause 78. The method according to any one of Clauses 70-77, wherein the method further comprises flow cytometrically analyzing the fluorescently labeled target analyte. 
     Clause 79. A method of labeling a target molecule, the method comprising: 
     contacting the target molecule with a polymeric dye to produce a labeled target molecule, wherein the polymeric dye comprises:
         a water soluble light harvesting multichromophore comprising a conjugated segment having the structure of formula (I):       

     
       
         
         
             
             
         
       
     
     wherein:
         each L is independently a conjugated backbone linking unit selected from a covalent bond, a vinylene group and an ethynylene group;   M 1  and M 2  are independently an aryl co-monomer or heteroaryl co-monomer;   each * is a site for covalent attachment to the unsaturated backbone of a conjugated polymer   n is an integer from 1 to 100,000; and       

     a conjugation tag that covalently links to the target molecule. 
     Clause 80. The method according to Clause 79, wherein the polymeric dye further comprises a signaling chromophore covalently linked to the multichromophore in energy-receiving proximity therewith. 
     Clause 81. The method according to any one of Clauses 79-80, further comprising fluorescently detecting the labeled target molecule. 
     Clause 82. The method according to any one of Clauses 79-81, wherein the conjugation tag comprises a terminal functional group selected from an amino, a thiol, a hydroxyl, a hydrazine, a hydrazide, a azide, an alkyne, maleimide, iodoacetyl, amine, an active ester and a protein reactive group.
 
Clause 83. The method according to any one of Clauses 79-82, wherein the target molecule is a specific binding member.
 
Clause 84. The method according to Clause 83, wherein the specific binding member is an antibody.
 
Clause 85. The method according to Clause 83, wherein the specific binding member is an antibody fragment or binding derivative thereof.
 
Clause 86. The method according to Clause 85, wherein the antibody fragment or binding derivative thereof is selected from the group consisting of a Fab fragment, a F(ab′) 2  fragment, a scFv, a diabody and a triabody.
 
Clause 87. A flow cytometric system, comprising:
 
     a flow cytometer comprising a flow path; 
     a composition in the flow path, wherein the composition comprises:
         a sample; and   a labeled specific binding member comprising:
           a water solvated light harvesting multichromophore comprising a conjugated segment having the structure of formula (I):   
               

     
       
         
         
             
             
         
       
         
         
           
             
               
                 wherein:
               each L is independently a conjugated backbone linking unit selected from a covalent bond, a vinylene and an ethynylene group;   M 1  and M 2  are independently an aryl or heteroaryl co-monomer;   each * is a site for covalent attachment to the unsaturated backbone of a conjugated polymer; and   n is an integer from 1 to 100,000; and   
             
                 a specific binding member that specifically binds a target analyte and is covalently linked to the multichromophore.
 
Clause 88. The system according to Clause 87, wherein the labeled specific binding member further comprises a signaling chromophore covalently linked to the multichromophore in energy-receiving proximity therewith.
 
Clause 89. The system according to any one of Clauses 87-88, wherein the composition further comprises a second specific binding member that is support bound and specifically binds the target analyte.
 
Clause 90. The system according to Clause 89, wherein the support comprises a magnetic particle.
 
Clause 91. The system according to any one of Clauses 89-90, wherein the sample comprises a cell.
 
Clause 92. The system according to Clause 91, wherein the target analyte is a cell surface marker of the cell.
 
Clause 93. The system according to Clause 92, wherein the cell surface marker is selected from the group consisting of a cell receptor and a cell surface antigen.
 
Clause 94. A kit comprising:
 
               
             
           
         
       
    
     a water solvated light harvesting multichromophore comprising a conjugated segment having the structure of formula (I): 
                         
wherein:
         each L is independently a conjugated backbone linking unit selected from a covalent bond, a vinylene and an ethynylene group;   M 1  and M 2  are independently an aryl or heteroaryl co-monomer;   each * is a site for covalent attachment to the unsaturated backbone of a conjugated polymer; and   n is an integer from 1 to 10,000; and       

     a container. 
     Clause 95. The kit according to Clause 94, further comprising one or more components selected from the group consisting of a polymeric tandem dye, a fluorophore, a specific binding member, a specific binding member conjugate, a cell, a support, a biocompatible aqueous elution buffer and instructions for use.
 
Clause 96. The kit according to any one of Clauses 94-95, wherein the multichromophore is described by any one of clauses 2-44.
 
Clause 97. The kit according to any one of Clauses 94-96, wherein the multichromophore is covalently linked to a specific binding member.
 
Clause 98. The kit according to Clause 97, wherein the specific binding member is an antibody.
 
Clause 99. The kit according to Clause 98, wherein the specific binding member is an antibody fragment or binding derivative thereof.
 
Clause 100. The kit according to Clause 99, wherein the antibody fragment or binding derivative thereof is selected from the group consisting of a Fab fragment, a F(ab′) 2  fragment, a scFv, a diabody and a triabody.
 
Clause 101. The kit according to any one of Clauses 94-100, wherein multichromophore further comprises an acceptor signaling chromophore covalently linked to the multichromophore in energy-receiving proximity therewith.
 
     Although the foregoing invention has been described in some detail by way of illustration and example for purposes of clarity of understanding, it is readily apparent to those of ordinary skill in the art in light of the teachings of this invention that certain changes and modifications may be made thereto without departing from the spirit or scope of the appended claims. 
     Accordingly, the preceding merely illustrates the principles of the invention. It will be appreciated that those skilled in the art will be able to devise various arrangements which, although not explicitly described or shown herein, embody the principles of the invention and are included within its spirit and scope. Furthermore, all examples and conditional language recited herein are principally intended to aid the reader in understanding the principles of the invention and the concepts contributed by the inventors to furthering the art, and are to be construed as being without limitation to such specifically recited examples and conditions. Moreover, all statements herein reciting principles, aspects, and embodiments of the invention as well as specific examples thereof, are intended to encompass both structural and functional equivalents thereof. Additionally, it is intended that such equivalents include both currently known equivalents and equivalents developed in the future, i.e., any elements developed that perform the same function, regardless of structure. The scope of the present invention, therefore, is not intended to be limited to the exemplary embodiments shown and described herein. Rather, the scope and spirit of present invention is embodied by the following.