Patent Description:
<CIT> discloses a composition comprising a primer that is (a) a loopable primer comprising a target-specific section, an adaptor section, and a stem-forming section, wherein the stem-forming section is hybridizable to a portion of the target-specific section to form a stem structure, or (b) a split primer comprising a first target-specific section, a second target-specific section, and an adaptor section positioned between the first target-specific section and the second target-specific section, or (c) a split-loopable primer comprising a first target-specific section, a second target-specific section, a stem-forming section positioned between the first target-specific section and the second target-specific section, and an adaptor section, or comprising a first adaptor section, a second adaptor section, a stem-forming section positioned between the first adaptor section and the second adaptor section, and a target-specific section. Also disclosed is a method for amplifying a target locus of interest from a template DNA, comprising at least two pre-amplification cycles using the loopable primer, the split primer and/or the split-loopable primer, wherein each amplification cycle comprises annealing the primer to the template DNA or pre-amplification product thereof and elongating the annealed primer. Further disclosed is a kit for amplifying a target locus of interest, comprising the loopable primer, the split primer, and/or the split-loopable primer.

<NPL>discloses Two-tailed RT-qPCR, a two-step RT-qPCR with SYBR-green detection chemistry, for quantification of microRNA. The target-specific primer for reverse transcription is composed of two hemiprobes complementary to two different parts of the target miRNA, connected by a hairpin structure.

The small size of circulating cell-free nucleic acids such as cfDNA proposes challenges for traditional sequencing and amplification-using analysis protocols. Provided herein are methods and compositions for improved isolation and amplification of cell-free nucleic acids such as cfDNA and cfRNA.

Further embodiments of the invention are defined in the dependent claims.

In some aspects, the present disclosure provides for a method for processing a polynucleotide sequence, the method comprising: combining in a reaction mixture suitable for processing said polynucleotide sequence: (i) said polynucleotide sequence; and (ii) a stem-loop primer that comprises: a <NUM>' arm sequence configured to hybridize to a complementary first end region of said target sequence; a stem-loop sequence containing a unique molecular identifier (UMI) and comprising a <NUM>' stem sequence, a loop sequence containing the UMI and a <NUM>' stem sequence; and a <NUM>' arm sequence configured to hybridize to a second end region of said target sequence. According to the invention, said first end region of said polynucleotide sequence is a <NUM>' region of said polynucleotide sequence and said second end region is a <NUM>' region of said polynucleotide sequence. In some embodiments, said <NUM>' arm sequence is substantially complementary to said first end region of said polynucleotide sequence. In some embodiments, said <NUM>' arm is sequence is substantially complementary to said second end region of said polynucleotide sequence. In some embodiments, said <NUM>' arm comprises at least <NUM>-<NUM> nucleotides perfectly complementary to said second end region of said polynucleotide sequence. In some embodiments, the <NUM>' most <NUM>-<NUM> nucleotides of said <NUM>' arm is perfectly complementary to said second end region of said polynucleotide sequence. In some embodiments, said target polynucleotide sequence comprises no fewer than <NUM> nucleotides between a <NUM>' end of said <NUM>' region of said polynucleotide sequence and a <NUM>' end of <NUM>' region of said polynucleotide sequence. In some embodiments, said <NUM>' arm sequence is capable of hybridizing to a region of said polynucleotide sequence no fewer than <NUM> nucleotides from a <NUM>' end of a region of said polynucleotide sequence to which said <NUM>' arm sequence is capable of hybridizing. In some embodiments, said polynucleotide sequence comprises DNA. In some embodiments, a polynucleotide molecule comprising said target polynucleotide sequence is <NUM> or fewer, <NUM> or fewer, <NUM> or fewer, or <NUM> or fewer nucleotides in length. In some embodiments, a polynucleotide molecule comprising said target polynucleotide sequence is <NUM> or greater, <NUM> or greater, <NUM> or greater, or <NUM> or greater nucleotides in length. In some embodiments, a polynucleotide molecule comprising said target polynucleotide sequence is not an miRNA. In some embodiments, said <NUM>' arm sequence comprises about <NUM>-<NUM>, about <NUM>-<NUM>, or about <NUM>-<NUM> nucleotides in length. In some embodiments, said <NUM>' arm sequence comprises about <NUM>-<NUM>, about <NUM>-<NUM>, or about <NUM>-<NUM> nucleotides in length. In some embodiments, said <NUM>' stem sequence or said <NUM>' stem sequence are about <NUM>-<NUM>, <NUM>-<NUM>, or <NUM>-<NUM> nucleotides in length. In some embodiments, said loop sequence is about <NUM>-<NUM> nucleotides in length. In some embodiments, said target polynucleotide sequence comprises no fewer than <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, or about <NUM>, or more nucleotides between a <NUM>' end of said <NUM>' region of said target DNA sequence and a <NUM>' end of <NUM>' region of said target sequence. In some embodiments, the method further comprises providing cell-free DNA comprising said target polynucleotide sequence. In some embodiments, providing cell-free DNA further comprises obtaining a serum or plasma sample from a subject. In some embodiments, the method further comprises incubating said reaction mixture under conditions suitable to produce extension products from said polynucleotide sequence. In some embodiments, the method further comprises sequencing said extension products. In some embodiments, said UMI comprises about <NUM>-<NUM> degenerate nucleotides.

In some aspects, the present disclosure provides for an oligonucleotide primer, comprising: a <NUM>' arm sequence configured to hybridize to a first end region of a polynucleotide sequence; a stem-loop sequence containing a UMI and comprising a <NUM>' stem sequence, a loop sequence containing the UMI and a <NUM>' stem sequence; and a <NUM>' arm sequence configured to hybridize to a second end region of said polynucleotide sequence. According to the invention, said first end region of said polynucleotide sequence is a <NUM>' region of said polynucleotide sequence and said second end region is a <NUM>' region of said polynucleotide sequence. In some embodiments, said <NUM>' arm sequence is substantially complementary to said first end region of said polynucleotide sequence. In some embodiments, said <NUM>' arm is sequence is substantially complementary to said second end region of said polynucleotide sequence. In some embodiments, said <NUM>' arm comprises at least <NUM>-<NUM> nucleotides perfectly complementary to said second end region of said polynucleotide sequence. In some embodiments, the <NUM>' most <NUM>-<NUM> nucleotides of said <NUM>' arm is perfectly complementary to said second end region of said polynucleotide sequence. In some embodiments, said target polynucleotide sequence comprises no fewer than <NUM> nucleotides between said first end region of said polynucleotide sequence and a said second end of said polynucleotide sequence. In some embodiments, said <NUM>' arm sequence is capable of hybridizing to a region of said polynucleotide sequence no fewer than <NUM> nucleotides from a <NUM>' end of a region of said polynucleotide sequence to which said <NUM>' arm sequence is capable of hybridizing. In some embodiments, said <NUM>' arm sequence comprises about <NUM>-<NUM>, about <NUM>-<NUM>, or about <NUM>-<NUM> nucleotides in length. In some embodiments, said <NUM>' arm sequence comprises about <NUM>-<NUM>, about <NUM>-<NUM>, or about <NUM>-<NUM> nucleotides in length. In some embodiments, said <NUM>' stem sequence or said <NUM>' stem sequence are about <NUM>-<NUM>, about <NUM>-<NUM>, or about <NUM>-<NUM> nucleotides in length. In some embodiments, said loop sequence is about <NUM>-<NUM> nucleotides in length. In some embodiments, said target polynucleotide sequence comprises no fewer than <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, or about <NUM>, or more nucleotides between a <NUM>' end of said <NUM>' region of said target DNA sequence and a <NUM>' end of <NUM>' region of said target sequence.

In some aspects, the present disclosure provides for a library of oligonucleotide primers, comprising a plurality of primers according to the disclosure, wherein the plurality of primers comprises a plurality of distinct unique molecular identifiers (UMIs).

Additional aspects and advantages of the present disclosure will become readily apparent to those skilled in this art from the following detailed description, wherein only illustrative embodiments of the present disclosure are shown and described. As will be realized, the present disclosure is capable of other and different embodiments, and its several details are capable of modifications in various obvious respects, all without departing from the disclosure. Accordingly, the drawings and description are to be regarded as illustrative in nature, and not as restrictive.

The terminology used herein is for the purpose of describing particular cases only and is not intended to be limiting. Furthermore, to the extent that the terms "including", "includes", "having", "has", "with", or variants thereof are used in either the detailed description and/or the claims, such terms are intended to be inclusive in a manner similar to the term "comprising.

The term "about" or "approximately" generally refers to an amount that is near the stated amount by about <NUM>%, <NUM>%, or <NUM>%, including increments therein. For example, "about" or "approximately" can mean a range including the particular value and ranging from <NUM>% below that particular value and spanning to <NUM>% above that particular value.

The practice of some methods disclosed herein employ, unless otherwise indicated, techniques of immunology, biochemistry, chemistry, molecular biology, microbiology, cell biology, genomics, and recombinant DNA. See for example <NPL>); the series Current Protocols in Molecular Biology (F. Ausubel, et al. ); the series <NPL>), <NPL>)), <NPL>, and <NPL>)).

The term "nucleotide", as used herein, generally refers to a base-sugar-phosphate combination. A nucleotide may comprise a synthetic nucleotide. A nucleotide may comprise a synthetic nucleotide analog. Nucleotides may be monomeric units of a nucleic acid sequence (e.g., deoxyribonucleic acid (DNA) and ribonucleic acid (RNA)). The term nucleotide may include ribonucleoside triphosphates adenosine triphosphate (ATP), uridine triphosphate (UTP), cytosine triphosphate (CTP), guanosine triphosphate (GTP) and deoxyribonucleoside triphosphates such as dATP, dCTP, dITP, dUTP, dGTP, dTTP, or derivatives thereof. Such derivatives may include, for example, [αS]dATP, <NUM>-deaza-dGTP and <NUM>-deaza-dATP, and nucleotide derivatives that confer nuclease resistance on the nucleic acid molecule containing them. The term nucleotide as used herein may refer to dideoxyribonucleoside triphosphates (ddNTPs) and their derivatives. Illustrative examples of dideoxyribonucleoside triphosphates may include, but are not limited to, ddATP, ddCTP, ddGTP, ddITP, and ddTTP. In some cases, a nucleotide comprises particular chemical modifications to the nucleotide base. Such chemical modifications can be important e.g. for encoding of epigenetic information or post-transcriptional gene regulation. In some cases, such chemical modifications include methylation of the nucleotide base, and include <NUM>-methylcytosine (<NUM>-mC), <NUM>-hydroxymethylcytosine (<NUM>-hmC), <NUM>-formylcytosine (<NUM>-fC) and <NUM>-carboxylcytosine (<NUM>-caC). In some cases, such chemical modifications include adenosine deamination (e.g. conversion of adenosine to inosine) and cytosine deamination (e.g. conversion of cytosine to uracil).

The terms "polynucleotide," "oligonucleotide," and "nucleic acid" are used interchangeably to generally refer to a polymeric form of nucleotides of any length, either deoxyribonucleotides or ribonucleotides, or analogs thereof, either in single-, double-, or multi-stranded form. A polynucleotide may be exogenous or endogenous to a cell. A polynucleotide may exist in a cell-free environment. A polynucleotide may be a gene or fragment thereof. A polynucleotide may be DNA. A polynucleotide may be RNA. A polynucleotide may have any three-dimensional structure and may perform any function. A polynucleotide may comprise one or more analogs (e.g., altered backbone, sugar, or nucleobase). If present, modifications to the nucleotide structure may be imparted before or after assembly of the polymer. Some non-limiting examples of analogs include: <NUM>-bromouracil, peptide nucleic acids, xeno nucleic acids, morpholinos, locked nucleic acids, glycol nucleic acids, threose nucleic acids, dideoxynucleotides, cordycepin, <NUM>-deaza-GTP, fluorophores (e.g., rhodamine or fluorescein linked to the sugar), thiol containing nucleotides, biotin linked nucleotides, fluorescent base analogs, CpG islands, methyl-<NUM>-guanosine, methylated nucleotides, inosine, thiouridine, pseudourdine, dihydrouridine, queuosine, and wyosine. Non-limiting examples of polynucleotides include coding or non-coding regions of a gene or gene fragment, loci (locus) defined from linkage analysis, exons, introns, messenger RNA (mRNA), transfer RNA (tRNA), small nuclear RNA (snRNA), ribosomal RNA (rRNA), genomic DNA (gDNA), cell-free DNA (cfDNA), and circulating tumor DNA (ctDNA).

A "subject" from which a sample is derived can be prokaryote or a eukaryote. The eukaryote can be a mammal. Mammals include, but are not limited to, domesticated animals (e.g., cows, sheep, cats, dogs, and horses), primates (e.g., humans and non-human primates such as monkeys), rabbits, and rodents (e.g., mice and rats). In certain embodiments, the subject or individual is a human.

In some cases, a sample is not from a subject, but is rather an environmental sample, comprising e.g. resident microorganisms or organic matter associated with higher organisms.

As used herein, the term "barcode" generally refers to a unique oligonucleotide sequence that allows a corresponding nucleic acid base and/or nucleic acid sequence, or a peptide or complex to which it is linked, to be identified. In some embodiments, the nucleic acid base and/or nucleic acid sequence is located at a specific position on a larger polynucleotide sequence, or a polynucleotide linked or connected to a peptide sequence. In some embodiments, a barcode is a "unique molecular identifier" (UMI). In some embodiments, barcodes can each have a length within a range of from <NUM> to <NUM> nucleotides, or from <NUM> to <NUM> nucleotides, or from <NUM> to <NUM> nucleotides. In some embodiments, the melting temperatures of barcodes within a set are within <NUM>° C. of one another, within <NUM>° C. of one another, or within <NUM>° C. of one another. In some embodiments, barcodes are members of a minimally cross-hybridizing set (e.g., the nucleotide sequence of each member of such a set is sufficiently different from that of every other member of the set that no member can form a stable duplex with the complement of any other member under stringent hybridization conditions). In some embodiments, the nucleotide sequence of each member of a minimally cross-hybridizing set differs from those of every other member by at least two nucleotides. Example barcode technologies are described in <NPL>; <NPL><NPL>; <NPL>; <NPL>; and <NPL>.

As used herein, the term "cell-free DNA" or "cfDNA" generally refers to strands of deoxyribose nucleic acids (DNA) found free of cells, for example, as extracted or isolated from plasma/serum of circulating blood, extracted from lymph, cerebrospinal fluid (CSF), urine or other bodily fluids. In some cases "cfDNA" comprises "circulating tumor DNA" or "ctDNA", or cell-free DNA that is free of tumor origin.

In some embodiments, the nucleic acids used in methods described herein can be amplified. Amplification can be performed at any point during a multi reaction procedure, e.g., before or after pooling of sequencing libraries from independent reaction volumes and may be used to amplify any suitable target molecule described herein.

Amplification can be performed by any suitable method. The nucleic acids may be amplified by polymerase chain reaction (PCR), as described in, for example, <CIT> and <CIT>. Other methods of nucleic acid amplification may include, for example, ligase chain reaction, oligonucleotide ligations assay, and hybridization assay, as described in greater detail in <CIT> and <CIT>. Real-time optical detection systems are also known in the art, as also described in greater detail in, for example, <CIT> and <CIT>. Other amplification methods that can be used herein include those described in <CIT>; <CIT>; <CIT>; and <CIT>.

Amplification may be achieved through any process by which the copy number of a target sequence is increased, e.g., PCR. Conditions favorable to the amplification of target sequences by PCR can be optimized at a variety of stages in the process, and can depend on characteristics of elements in the reaction, such as target type, target concentration, sequence length to be amplified, sequence of the target and/or one or more primers, primer length, primer concentration, polymerase used, reaction volume, ratio of one or more elements to one or more other elements, and others, some, or all of which can be altered. In general, PCR involves denaturation of the target to be amplified (if double stranded), hybridization of one or more primers to the target, and extension of the primers by a DNA polymerase, with the stages repeated (or "cycled") in order to amplify the target sequence. Stages in this process can be optimized for various outcomes, such as to enhance yield, decrease the formation of spurious products, and/or increase or decrease specificity of primer annealing. Methods of optimization are well known in the art and include adjustments to the type or amount of elements in the amplification reaction and/or to the conditions of a given stage in the process, such as temperature at a particular stage, duration of a particular stage, and/or number of cycles. In some embodiments, an amplification reaction comprises at least <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, or more cycles. In some embodiments, an amplification reaction comprises no more than <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, or more cycles. Cycles can contain any number of stages, such as <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM> or more stages. Stages can comprise any temperature or gradient of temperatures, suitable for achieving the purpose of the given stage, including but not limited to, <NUM>' end extension (e.g., adaptor fill-in), primer annealing, primer extension, and strand denaturation. Stages can be of any duration, including but not limited to about, less than about, or more than about <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, or more seconds, including indefinitely until manually interrupted. Cycles of any number comprising different stages can be combined in any order. In some embodiments, different cycles comprising different stages are combined such that the total number of cycles in the combination is about, less that about, or more than about <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, or more cycles.

In some embodiments of the present disclosure, methods or systems described involve obtaining a sample from a subject or patient or involve the use of such a sample. Samples used in the methods of the provided disclosure can include, for example, a bodily fluid from a subject, including bile, blood and blood plasma, interstitial fluid, lymph, mucus (including snot and phlegm), pleural fluid, saliva, internal body fluids, including cerebrospinal fluid surrounding the brain and the spinal cord, synovial fluid surrounding bone joints, intracellular fluid inside cells, and vitreous humour in the eyeball. In one embodiment, the sample is a blood sample. The blood sample can be about <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, or more.

Human biofluids contain cells and also cell-free sources of molecules. Cell-free sources include extracellular vesicles and the molecules carried within (e.g. RNA, DNA, lipids, small metabolites, and proteins) and also cell-free DNA.

Samples can be collected and/or analyzed at a time when a disease of the subject is inactive. Samples can be collected and/or analyzed at a time when a disease of the subject is known to be active.

The sample can be obtained by a particular individual. The sample can be obtained by a health care provider, for example, a physician, physician assistant, nurse, veterinarian, dermatologist, rheumatologist, dentist, paramedic, or surgeon. The sample can be obtained by a research technician. More than one sample from a subject can be obtained.

As used herein "obtaining a sample" generally includes obtaining a sample directly or indirectly. In some embodiments, the sample is taken from the subject by the same party (e.g. a testing laboratory) that subsequently acquires biomarker data from the sample. In some embodiments, the sample is received (e.g. by a testing laboratory) from another entity that collected it from the subject (e.g. a physician, nurse, phlebotomist, or medical caregiver). In some embodiments, the sample is taken from the subject by a medical professional under direction of a separate entity (e.g. a testing laboratory) and subsequently provided to said entity (e.g. the testing laboratory). In some embodiments, the sample is taken by the subject or the subject 's caregiver at home and subsequently provided to the party that acquires biomarker data from the sample (e.g. a testing laboratory).

In some aspects, the present disclosure provides for a method for processing a polynucleotide sequence, the method comprising: combining in a reaction mixture suitable for processing said polynucleotide sequence: (i) said polynucleotide sequence; and (ii) a stem-loop primer. As used herein, the term "stem-loop" generally refers to a nucleic acid secondary structure in which a single strand of nucleic acid, e.g., DNA or RNA, has two self-complementary sequences, separated by some length of intervening sequence, such that the self-complementary sequences can hybridize to form a base paired "stem" connected by a "loop" made up of the non-base paired intervening sequence. The "stem" of a stem-loop will generally be of sufficient length to be stable in an amplification reaction (e.g. a PCR reaction) at the extension temperature used for the reaction. In some cases, stability of hybridization (or temperature of melting or Tm) is affected by the G/C and A/T content of the self-complementary sequences, and the length of the self-complementary sequences. In some cases, the stem of the stem loop is configured to hybridize only within particular temperature ranges (e.g. the Tm is altered such that the self-complementary sequences only hybridize to each other below a particular temperature). In some cases, the Tm of the interaction between the self-complementary (e.g. stem sequences) is between about <NUM> and about <NUM>, between about <NUM> and about <NUM>, between about <NUM> and about <NUM> , between about <NUM> and about <NUM>, or between about <NUM> and about <NUM>. In some cases, the Tm of the interaction between the self-complementary (e.g. stem sequences) is at least about <NUM>, at least about <NUM>, at least about <NUM>, at least about <NUM>, at least about <NUM>, at least about <NUM>, at least about <NUM>, at least about <NUM>, at least about <NUM>, at least about <NUM>, at least about <NUM>, at least about <NUM>, at least about <NUM>, at least about <NUM>, at least about <NUM>, at least about <NUM>, at least about <NUM>, at least about <NUM>, at least about <NUM>, at least about <NUM>, at least about <NUM>, at least about <NUM>, at least about <NUM>, or more. In some cases, the Tm of the interaction between the self-complementary (e.g. stem sequences) is at most about <NUM>, at most about <NUM>, at most about <NUM>, at most about <NUM>, at most about <NUM>, at most about <NUM>, at most about <NUM>, at most about <NUM>, at most about <NUM>, at most about <NUM>, at most about <NUM>, at most about <NUM>, at most about <NUM>, at most about <NUM>, at most about <NUM>, at most about <NUM>, at most about <NUM>, at most about <NUM>, at most about <NUM>, at most about <NUM>, at most about <NUM>, at most about <NUM>, or more. In some cases, the self-complementary sequences are at least about <NUM>, at least about <NUM>, at least about <NUM>, at least about <NUM>, at least about <NUM>, at least about <NUM>, at least about <NUM>, at least about <NUM>, at least about <NUM>, at least about <NUM>, at least about <NUM>, at least about <NUM>, at least about <NUM>, at least about <NUM>, at least about <NUM>, at least about <NUM>, at least about <NUM>, at least about <NUM>, at least about <NUM>, or more nucleotides in length. In some cases, the self-complementary sequences are no more than about <NUM>, no more than about <NUM>, no more than about <NUM>, no more than about <NUM>, no more than about <NUM>, no more than about <NUM>, no more than about <NUM>, no more than about <NUM>, no more than about <NUM>, no more than about <NUM>, no more than about <NUM>, no more than about <NUM>, no more than about <NUM>, or no more than about <NUM> nucleotides in length. In some cases, the self-complementary sequences are at least about <NUM> to at least about <NUM> nucleotides in length. In some cases, the self-complementary sequences are at least about <NUM> to at least about <NUM> nucleotides in length. In some cases, the self-complementary sequences are at least about <NUM> to at least about <NUM> nucleotides in length. In some cases, the self-complementary sequences are at least about <NUM> to at least about <NUM> nucleotides in length. In some cases, the self-complementary sequences comprise a sequence having at least <NUM>%, at least <NUM>%, at least <NUM>%, at least <NUM>%, at least <NUM>%, at least <NUM>%, or a sequence that is substantially identical to at least one sequence from Table <NUM> or a complement or variant thereof.

In some cases, the stem-loop primer may comprise a nucleotide analogue, such as a modified nucleic acid, or other non-canonical nucleotide. Other non-limiting examples of nucleotide analogues include but are not limited to <NUM>-Aminopurine, <NUM>,<NUM>- Diaminopurine, <NUM>-Bromo dU, deoxyUridine, Inverted dT, dideoxy nucleotides, <NUM>-Methyl dC, deoxylnosine, locked nucleic acids (LNAs), <NUM>-Nitroindole, <NUM>'-O-Methyl RNA Bases, <NUM>'-F RNA Bases, <NUM>-bromouracil, peptide nucleic acids, xeno nucleic acids, morpholinos, glycol nucleic acids, threose nucleic acids, dideoxynucleotides, cordycepin, <NUM>-deaza-GTP, fluorophores (e.g., rhodamine or fluorescein linked to the sugar), thiol containing nucleotides, biotin linked nucleotides, fluorescent base analogs, CpG islands, methyl-<NUM>-guanosine, methylated nucleotides, inosine, thiouridine, pseudourdine, dihydrouridine, queuosine, and wyosine.

In some embodiments, the polynucleotide sequence for processing is a sequence present in a nucleic acid mixture from a biological sample. Samples include any of the samples described herein. In some cases, the sample is a blood, peripheral blood, serum, or plasma sample. In some cases, the sample comprises DNA. In some cases, the sample comprises cell-free DNA (cfDNA). In some cases, the polynucleotide sequence comprises DNA. In some cases, the polynucleotide sequence comprises cfDNA or ctDNA. In some cases, plasma is purified by centrifugation to remove cellular matter before cfDNA isolation. In some cases, cfDNA is isolated from a blood, peripheral blood, serum, or plasma sample by silica membrane chromatography or polymer-mediated enrichment. The polynucleotide molecule comprising said target polynucleotide sequence can be <NUM> or fewer, <NUM> or fewer, <NUM> or fewer, <NUM> or fewer, <NUM> or fewer, <NUM> or fewer, <NUM> or fewer, <NUM> or fewer, <NUM> or fewer, <NUM> or fewer, <NUM> or fewer, or <NUM> or fewer nucleotides in length. The polynucleotide molecule comprising said target polynucleotide sequence can be <NUM> or greater, <NUM> or greater, <NUM> or greater, <NUM> or greater, <NUM> or greater, <NUM> or greater, <NUM> or greater, or <NUM> or greater nucleotides in length. In some cases, the polynucleotide molecule comprising the target polynucleotide comprises RNA. In some cases, the polynucleotide molecule comprising the target polynucleotide does not comprise RNA. In some cases, polynucleotide molecule comprising said target polynucleotide sequence is not an miRNA or snRNA. The polynucleotide molecule comprising said target polynucleotide sequence may comprise no fewer than about <NUM> nucleotides, no fewer than about <NUM> nucleotides, no fewer than about <NUM> nucleotides, no fewer than about <NUM> nucleotides, no fewer than about <NUM> nucleotides, no fewer than about <NUM> nucleotides, or no fewer than about <NUM> nucleotides between a <NUM>' end (e.g. a first stem-loop arm hybridization site) of said <NUM>' region of said polynucleotide sequence and a <NUM>' end of <NUM>' region (e.g. a second stem-loop arm hybridization site) of said polynucleotide sequence. In some cases, the biological sample is from any of the subjects described herein.

In some cases, the stem-loop primer comprises a <NUM>' arm sequence configured to hybridize to a first end region of the target sequence. As used herein, the term "hybridize" generally refers to the physical interaction between complementary regions of two single-stranded nucleic acid molecules creating a double-stranded structure. In some cases, "hybridize" refers to promoting interactions between present oligonucleotides and their target polynucleotides under hybridization conditions that allow complementary regions of the two molecules to interact by hydrogen bonding and remain engaged. Modifiable variables of the hybridization conditions include, but are not limited to, duration (typically from seconds to some hours), temperature (generally from about <NUM> to about <NUM>), salt composition and concentration, chaotropic agent composition (e.g., formamide, or dimethyl sulfoxide (DMSO)) and concentration, and usage of substances that decrease non-specific binding (e.g., bovine serum albumin (BSA), or salmon sperm DNA (ssDNA)). In some cases, the <NUM>' arm sequence is substantially complementary to said first end region of said polynucleotide sequence. The <NUM>' arm can comprise at least about <NUM>, at least about <NUM>, at least about <NUM>, at least about <NUM>, at least about <NUM>, at least about <NUM>, at least about <NUM>, at least about <NUM>, at least about <NUM>, at least about <NUM>, at least about <NUM>, at least about <NUM>, at least about <NUM>, at least about <NUM>, at least about <NUM>, at least about <NUM>, at least about <NUM>, or at least about <NUM> nucleotides perfectly complementary to said second end region of said polynucleotide sequence. The <NUM>' arm can comprise no fewer than about <NUM> nucleotides, about <NUM> nucleotides, about <NUM> nucleotides, about <NUM> nucleotides, about <NUM> nucleotides, about <NUM> nucleotides, about <NUM> nucleotides, about <NUM> nucleotides, about <NUM> nucleotides, or about <NUM> nucleotides. In some cases, the <NUM>' arm sequence comprises about <NUM>-<NUM>, about <NUM>-<NUM>, or about <NUM>-<NUM> nucleotides in length. The <NUM>' arm may be configured (e.g. by length, complementarity, nucleotide composition, or addition of non-natural nucleotides) such that the sequence to which it is substantially complementary can fall within a particular temperature range, such as between about <NUM> and about <NUM>, between about <NUM> and about <NUM>, between <NUM> and <NUM>, or between <NUM> and <NUM>. In some cases, the <NUM>' arm may be configured (e.g. by length, complementarity, nucleotide composition, or addition of non-natural nucleotides) to have a lower Tm with its complementary sequence than the Tm of the "stem" sequence (e.g. of the self-complementary sequences in the stem). In some cases, the Tm of the <NUM>' arm with its complementary sequence (or the combined Tm of the <NUM>' and <NUM>' hemiprobes with their complementary sequence, if a two-hemiprobe primer design is used) is at least <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, or more degrees lower than the Tm of the stem sequence. In some cases, the Tm of the <NUM>' arm with its complementary sequence (or the combined Tm of the <NUM>' and <NUM>' hemiprobes with their complementary sequence, if a two-hemiprobe primer design is used) is at least <NUM>-<NUM> lower than the Tm of the stem sequence. The <NUM>' most <NUM>-<NUM> nucleotides of said <NUM>' arm may be perfectly complementary to said first end region of said polynucleotide sequence. In some cases, the primer comprises two hemiprobes,.

In some cases, the stem-loop primer further comprises a loop sequence containing a barcode. In some cases, the barcode is a unique molecular identifier (UMI). The term "UMI", or "Unique Molecular Identifier", as used herein, generally refers to a tag, consisting of a sequence of degenerate bases, which is used to label original molecules in a sheared nucleic acid sample. As such, UMIs can be used to determine if two, similar sequence reads are each derived from a different, original fragment or if they are simply duplicates created during PCR amplification of the library, which were derived from the same original fragment. In some cases, UMIs can be used in combination with start stop sites, for consensus calling of rare sequence variants. In some cases, a UMI comprises about <NUM>-<NUM> degenerate nucleotides. In some cases, a UMI comprises at least about <NUM>, at least about <NUM>, at least about <NUM>, at least about <NUM>, at least about <NUM>, at least about <NUM>, at least about <NUM>, at least about <NUM>, at least about <NUM>, at least about <NUM>, at least about <NUM>, at least about <NUM>, at least about <NUM>, at least about <NUM>, or at least about <NUM> degenerate nucleotides. In some cases, a UMI comprises at most about <NUM>, at most about <NUM>, at most about <NUM>, at most about <NUM>, at most about <NUM>, at most about <NUM>, at most about <NUM>, at most about <NUM>, at most about <NUM>, at most about <NUM>, at most about <NUM>, at most about <NUM>, at most about <NUM>, or at most about <NUM> degenerate nucleotides. In some cases, the UMI is flanked by a constant universal sequence to facilitate interrogation at later sequencing steps.

In some cases, the stem-loop primer further comprises a <NUM>' arm sequence configured to hybridize to a second end region of said target sequence. In some cases, the <NUM>' arm is sequence is substantially complementary to said second end region of said polynucleotide sequence. The <NUM>' arm can comprise at least about <NUM>, at least about <NUM>, at least about <NUM>, at least about <NUM>, at least about <NUM>, at least about <NUM>, at least about <NUM>, at least about <NUM>, at least about <NUM>, at least about <NUM>, at least about <NUM>, at least about <NUM>, at least about <NUM>, at least about <NUM>, at least about <NUM>, at least about <NUM>, at least about <NUM>, or at least about <NUM> nucleotides perfectly complementary to said second end region of said polynucleotide sequence. The <NUM>' arm can comprise no fewer than about <NUM> nucleotides, about <NUM> nucleotides, about <NUM> nucleotides, about <NUM> nucleotides, about <NUM> nucleotides, about <NUM> nucleotides, about <NUM> nucleotides, about <NUM> nucleotides, about <NUM> nucleotides, or about <NUM> nucleotides. In some cases, the <NUM>' arm sequence comprises about <NUM>-<NUM>, about <NUM>-<NUM>, or about <NUM>-<NUM> nucleotides in length. The <NUM>' arm may be configured (e.g. by length, complementarity, nucleotide composition, or addition of non-natural nucleotides) such that the sequence to which it is substantially complementary can fall within a particular temperature range, such as between about <NUM> and about <NUM>, between about <NUM> and about <NUM>, between <NUM> and <NUM>, or between <NUM> and <NUM>. In some cases, the <NUM>' arm (or in the case of a primer with two hemiprobes, the combined <NUM> ' and <NUM> ' hemiprobe) may be configured (e.g. by length, complementarity, nucleotide composition, or addition of non-natural nucleotides) to have a lower Tm with its complementary sequence than the Tm of the "stem" sequence (e.g. of the self-complementary sequences in the stem). In some cases, the Tm of the <NUM>' arm with its complementary sequence is at least <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, or more degrees lower than the Tm of the stem sequence. In some cases, the <NUM>' arm may be configured to have a Tm with its complementary sequence substantially equal to the Tm of the <NUM>' arm with its complementary sequence, or a Tm within <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, or <NUM> of the Tm of the <NUM>' arm with its complementary sequence. The <NUM>' most <NUM>-<NUM> nucleotides of the <NUM>' arm may perfectly be complementary to said second end region of said polynucleotide sequence. In some cases, said <NUM>' arm sequence is capable of hybridizing to a region of said polynucleotide sequence no fewer than about <NUM> nucleotides, no fewer than about <NUM> nucleotides, no fewer than about <NUM> nucleotides, no fewer than about <NUM> nucleotides, no fewer than about <NUM> nucleotides, no fewer than about <NUM> nucleotides, or no fewer than about <NUM> nucleotides from a <NUM>' end of a region of said polynucleotide sequence to which said <NUM>' arm sequence is capable of hybridizing. In some cases, the first end region of said polynucleotide sequence is a <NUM>' region of said polynucleotide sequence and said second end region is a <NUM>' region of said polynucleotide sequence.

In some cases, the method further comprises incubating said reaction mixture under conditions suitable to produce extension products from said polynucleotide sequence. Conditions suitable to produce extension products include but are not limited to any conditions suitable to extend a primer (e.g. a stem-loop primer) described herein in a template-directed manner. Such conditions include any amplification method described herein, RT-PCR, RT-qPCR, qPCR, PCR, LAMP, SDA, recombinase polymerase amplification, sanger sequencing, or RNA transcription. In some cases, incubating the reaction mixture under conditions to produce extension products from said polynucleotide sequence (e.g. in the presence of a stem-loop primer described herein) causes production of extension products from the polynucleotide sequence with particular characteristics). The extension products produced may have a particular purity, such as at least about <NUM>%, at least about <NUM>%, at least about <NUM>%, at least about <NUM>%, at least about <NUM>%, at least about <NUM>%, at least about <NUM>%, at least about <NUM>%, at least about <NUM>%, at least about <NUM>%, at least about <NUM>%, at least about <NUM>%, at least about <NUM>%, at least about <NUM>%, at least about <NUM>%, at least about <NUM>%, at least about <NUM>%, at least about <NUM>%, at least about <NUM>%, at least about <NUM>%, at least about <NUM>%, at least about <NUM>%, at least about <NUM>%, at least about <NUM>%, at least about <NUM>%, at least about <NUM>%, at least about <NUM>%, at least about <NUM>%, at least about <NUM>%, at least about <NUM>%, at least about <NUM>%, or at least about <NUM>% products containing said polynucleotide sequence.

In some cases, the method further comprises performing a sequencing assay on the extension products produced in the reaction mixture. The sequencing assay may comprise (i) exome sequencing, (ii) sequencing a panel of genes, (iii) whole genome sequencing, (iv) sequencing by synthesis using reversible terminator chemistry, (v) pyrosequencing, (vi) nanopore sequencing, (vii) real-time single molecule sequencing, (viii) sanger sequencing, or any combination thereof. Sequencing can be performed by various systems currently available, such as, without limitation, a sequencing system by Illumina®, Pacific Biosciences (PacBio®), Oxford Nanopore®, or Life Technologies (Ion Torrent®). Alternatively or in addition, sequencing may be performed using nucleic acid amplification, polymerase chain reaction (PCR) (e.g., digital PCR, quantitative PCR, or real-time PCR), or isothermal amplification.

In some aspects, the present disclosure provides for a stem-loop primer as described herein, a reaction mixture suitable for DNA amplification, or a reaction mixture suitable for production of extension products comprising a stem-loop primer as described herein.

In some aspects, the present disclosure provides for a library of oligonucleotide primers, comprising a plurality of stem-loop primers as described herein, wherein the plurality of stem-loop primers comprises a plurality of distinct unique molecular identifiers (UMIs). The library can comprise at least about <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>×<NUM><NUM>, <NUM>×<NUM><NUM>, <NUM>×<NUM><NUM>, <NUM>×<NUM><NUM>, or <NUM>×<NUM><NUM> members, or more.

In some aspects, the present disclosure provides for a method for processing a polynucleotide sequence, the method comprising: combining in a reaction mixture suitable for extension of polynucleotide primers: (i) said polynucleotide sequence; and (ii) a primer that comprises: a terminal hydrophobic group. In some cases, the primer further comprises a unique molecular identifier (UMI) as described herein. In some cases, the primer further comprises a <NUM>' arm sequence capable of hybridizing to a first end region of said polynucleotide sequence (e.g. a <NUM>' arm sequence as described herein). In some cases, the primer further comprises a <NUM>' arm sequence capable of hybridizing to a first end region of said polynucleotide sequence (e.g. a <NUM>' arm sequence as described herein). In some cases, the primer is a stem-loop primer as described herein. In some cases, the stem-loop primer comprises a UMI or a barcode as described herein.

The hydrophobic group can comprise any group having hydrophobicity greater than the natural <NUM>'-OH of a DNA polynucleotide. Such groups include, but are not limited to, the <NUM>' Uni-Link™ Amino Modifier (5UniAmM), <NUM>' PC Biotin (5PCBio), <NUM>' Dual Biotin (<NUM>-Bio), <NUM>' Amino Modifier C12 (5AmMC12), <NUM>' Amino Modifier C6 (5AmMC6), <NUM>' Hexynyl (5Hexynyl), <NUM>' <NUM>-Octadiynyl dU (550ctdU), <NUM>' Desthiobiotin-TEG (5deSBioTEG), <NUM>' Biotin (5biosg), or <NUM>' Biotin-TEG (5BiotinTEG), or any of the modifying groups depicted in. In some embodiments, the hydrophobic group is <NUM>' Desthiobiotin-TEG (5deSBioTEG), <NUM>' Biotin (5biosg), or <NUM>' Biotin-TEG (5BiotinTEG). The hydrophobic group can be <NUM>' Desthiobiotin-TEG (5deSBioTEG). The hydrophobic group can be <NUM>' Biotin (5biosg). The hydrophobic group can be <NUM>' Biotin-TEG (5BiotinTEG) In some cases, the method further comprises incubating said reaction mixture under conditions suitable to produce extension products from said polynucleotide sequence, wherein (b) is performed in absence of purification of said amplification products. Conditions suitable to produce extension products include but are not limited to any conditions suitable to extend a primer (e.g. a stem-loop primer) described herein in a template-directed manner. Such conditions include any amplification method described herein, RT-PCR, RT-qPCR, qPCR, PCR, LAMP, SDA, recombinase polymerase amplification, sanger sequencing, or RNA transcription. In some cases, incubating the reaction mixture under conditions to produce extension products from said polynucleotide sequence (e.g. in the presence of a stem-loop primer described herein) causes production of extension products from the polynucleotide sequence with particular characteristics). The extension products produced may have a particular purity, such as at least about as at least about <NUM>%, at least about <NUM>%, at least about <NUM>%, at least about <NUM>%, at least about <NUM>%, at least about <NUM>%, at least about <NUM>%, at least about <NUM>%, at least about <NUM>%, at least about <NUM>%, at least about <NUM>%, at least about <NUM>%, at least about <NUM>%, at least about <NUM>%, at least about <NUM>%, at least about <NUM>%, at least about <NUM>%, at least about <NUM>%, at least about <NUM>%, at least about <NUM>%, at least about <NUM>%, at least about <NUM>%, at least about <NUM>%, at least about <NUM>%, at least about <NUM>%, at least about <NUM>%, at least about <NUM>%, at least about <NUM>%, at least about <NUM>%, at least about <NUM>%, at least about <NUM>%, or at least about <NUM>% products containing said polynucleotide sequence in the absence of purification. Alternatively or additionally, the extension products produced may comprise fewer than about <NUM>%, fewer than about <NUM>%, fewer than about <NUM>%, fewer than about <NUM>%, fewer than about <NUM>%, fewer than about <NUM>%, fewer than about <NUM>%, fewer than about <NUM>%, fewer than about <NUM>%, fewer than about35%, fewer than about <NUM>%, fewer than about <NUM>%, fewer than about <NUM>%, fewer than about <NUM>%, fewer than about <NUM>%, fewer than about <NUM>%, fewer than about <NUM>%, fewer than about <NUM>%, fewer than about <NUM>%, fewer than about <NUM>%, fewer than about <NUM>%, fewer than about <NUM>%, fewer than about <NUM>%, fewer than about <NUM>%, fewer than about <NUM>%, fewer than about <NUM>%, fewer than about <NUM>%, fewer than about <NUM>%, fewer than about <NUM>%, fewer than about <NUM>%, fewer than about <NUM>%, fewer than about <NUM>%, fewer than about <NUM>%, fewer than about <NUM>%, fewer than about <NUM>%, fewer than about <NUM>%, or less products that do not contain said polynucleotide target sequence in the absence of purification.

The reaction mixture can comprise a second primer comprising a <NUM>' arm sequence configured to hybridize to a second end region of said polynucleotide sequence (e.g. a <NUM>' arm sequence as described herein). In some cases, the second primer comprises a terminal hydrophobic group. The hydrophobic group can comprise any group having hydrophobicity greater than the natural <NUM>'-OH of a DNA polynucleotide. Such groups include, but are not limited to the <NUM>' Uni-Link™ Amino Modifier (5UniAmM), <NUM>' PC Biotin (5PCBio), <NUM>' Dual Biotin (<NUM>-Bio), <NUM>' Amino Modifier C12 (5AmMC12), <NUM>' Amino Modifier C6 (5AmMC6), <NUM>' Hexynyl (5Hexynyl), <NUM>' <NUM>-Octadiynyl dU (55OctdU), <NUM>' Desthiobiotin-TEG (5deSBioTEG), <NUM>' Biotin (5biosg), or <NUM>' Biotin-TEG (5BiotinTEG).

In some embodiments, the polynucleotide sequence for processing is a sequence present in a nucleic acid mixture from a sample from a subject. Samples include any of the samples described herein. In some cases, the sample is a blood, peripheral blood, serum, or plasma sample. In some cases, the sample comprises DNA. In some cases, the sample comprises cell-free DNA (cfDNA). In some cases, the polynucleotide sequence comprises DNA. In some cases, the polynucleotide sequence comprises cfDNA or ctDNA. In some cases, plasma is purified by centrifugation to remove cellular matter before cfDNA isolation. In some cases, cfDNA is isolated from a blood, peripheral blood, serum, or plasma sample by silica membrane chromatography or polymer-mediated enrichment. The polynucleotide molecule comprising said target polynucleotide sequence can be <NUM> or fewer, <NUM> or fewer, <NUM> or fewer, <NUM> or fewer, <NUM> or fewer, <NUM> or fewer, <NUM> or fewer, <NUM> or fewer, <NUM> or fewer, <NUM> or fewer, <NUM> or fewer, or <NUM> or fewer nucleotides in length. The polynucleotide molecule comprising said target polynucleotide sequence can be <NUM> or greater, <NUM> or greater, <NUM> or greater, <NUM> or greater, <NUM> or greater, <NUM> or greater, <NUM> or greater, or <NUM> or greater nucleotides in length. In some cases, the polynucleotide molecule comprising the target polynucleotide comprises RNA. In some cases, the polynucleotide molecule comprising the target polynucleotide does not comprise RNA. In some cases, polynucleotide molecule comprising said target polynucleotide sequence is not an miRNA or snRNA. The polynucleotide molecule comprising said target polynucleotide sequence may comprise no fewer than about <NUM> nucleotides, no fewer than about <NUM> nucleotides, no fewer than about <NUM> nucleotides, no fewer than about <NUM> nucleotides, no fewer than about <NUM> nucleotides, no fewer than about <NUM> nucleotides, or no fewer than about <NUM> nucleotides between a <NUM>' end (e.g. a first arm hybridization site) of said <NUM>' region of said polynucleotide sequence and a <NUM>' end of <NUM>' region (e.g. a second arm hybridization site) of said polynucleotide sequence.

Primers are constructed as depicted in <FIG>: a <NUM>' stem-loop primer bearing a <NUM> ' stem-loop containing a barcode and a universal sequence (green) and a <NUM>' hybridization region to a upstream region of a cfDNA sequence (orange); and a <NUM>' primer having a hybridization region to a downstream region of a cfDNA(red) and a universal sequence (green). These primers are incubated under amplification conditions with a suitable sample containing the cfDNA sequence. The resulting amplification products are analyzed by sequencing. Sequence filtering on the barcode sequence allows for identification and quantitation of the amplicons resulting from the specific cfDNA amplification reaction.

Forward primers targeted against the p53 gene with the sequence <NUM>'-GGACACTCTTTCCCTACACGACGCTCTTCCGATCTNNNNNNNNNNNNATGGGAAAGAGT GTCCGTGGCAAGTGGCTCCTGA-<NUM>' (SEQ ID NO: <NUM>, where N denotes degenerate residues) were modified to bear the <NUM>' modifications shown in <FIG> and were used with reverse primer <NUM>'-GTGACTGGAGTTCAGACGTGTGCTCTTCCGATCTCATGGGCGGCATGAAC -<NUM>' (SEQ ID NO: <NUM>, which also targets the p53 gene) to amplify human genomic DNA (positive) and nuclease free water (negative). The results of this experiment are presented in <FIG>, which depicts the change in cycle time between samples containing the target sequence and samples not containing the target sequence.

To demonstrate amplification of DNA to produce a barcoded sequence as described herein using a <NUM>-tailed forward primer, a primer was designed according to panel B in <FIG> to amplify a sequence present in the NRAS gene.

This primer (designated GJ8) comprises of the sequence <NUM>'-TACAGTGCCATGAGAGACCA-TTATCCT-GGACACTCTTTCCCTACACGACGCTCTTCCGATCT-NNNNNNNNNNNN-AT-GGGAAAGAGTGTCC-TCTA-CGCTGGACAAG-<NUM>' (SEQ ID NO: <NUM>) where dashes are not part of the sequence but use here to visually distinguish the elements in the <NUM>' to <NUM>' direction; a <NUM>' hemiprobe, a spacer, an adapter, a molecular barcode, a splitter, a sequence complementary to a section of the adapter capable of forming a hairpin, a spacer, and a <NUM>' hemiprobe).

A corresponding reverse primer was also designed according to the scheme outlined in panel B of <FIG>, and comprised the sequence <NUM>'-GTGACTGGAGTTCAGACGTGTGCTCTTCCGATCTACACAAAGATCATCCTTTCAGAGA-<NUM>' (SEQ ID NO: <NUM>).

These two primers were used to amplify a synthetic DNA construct with similarities to the NRAS gene, which comprised the sequence <NUM>'-CAGCTGGACAAGTAATATACAGTGCCATGAGAGACCAATACATGAGGACTAATATAAT AATTATTTTCTCTGAAAGGATGATCTTTGTGTTCTAGT-<NUM>' (SEQ ID NO: <NUM>), where the first and second bolded elements denote the <NUM>' and <NUM>' hemiprobe binding sites, respectively, and the third bolded sequence denotes the binding site for the reverse primer. Using the reaction procedure detailed below, <NUM>,<NUM> synthetic DNA molecules were amplified in a barcoding reaction and further processed to create a sequencing library in a second PCR reaction using Illumina index adapters.

The amplification was assembled in a <NUM>µL reaction, containing forward and reverse primers above, synthetic template, 1x Platinum Superfi buffer, <NUM> U platinum Superfi Polymerase (both from Thermo Fisher Scientific), <NUM> dNTP (Sigma-Aldrich), <NUM> of two-tailed and reverse primers (Ultramere, IDT), and <NUM> L-carnitine inner salt (Sigma-Aldrich).

The amplification reaction was run on a T100 Thermal cycler (Bio-Rad) with the following thermal program; <NUM> sec at <NUM>, followed by <NUM> cycles of amplification (<NUM> for <NUM> sec, <NUM> for <NUM>, <NUM> for <NUM> sec), <NUM> at <NUM> and <NUM> at <NUM>.

At the start of the <NUM> incubation step at <NUM>, <NUM>µl of <NUM> ng/µL Streptomyces griseus protease (Sigma-Aldrich) solution dissolved in 1x TE-buffer (pH <NUM>, Thermo Fisher Scientific) was added to each well, to attenuate and degrade the polymerase.

<NUM>µl of the resultant amplified product were then amplified with Illumina Universal forward primer and Illumina index reverse primer (desalted, Sigma-Aldrich, table <NUM>) in a <NUM>µL reaction containing, 1x Q5 Hot Start High-Fidelity Master Mix (New England BioLabs) and <NUM> of each primer using the following thermal program on a T100 Thermal cycler; <NUM> for <NUM>, <NUM> cycles of amplification; <NUM> for <NUM> sec, <NUM> for <NUM> sec, <NUM> for <NUM> sec, <NUM> for <NUM> sec, all with ramping at <NUM>/s. The Illumina universal forward primer comprised the sequence <NUM>'-AATGATACGGCGACCACCGAGATCTACACTCTTTCCCTACACGACGCTCTTCCGATCT-<NUM>' (SEQ ID NO: <NUM>), and the Illumina index reverse primer comprised the sequence <NUM>'-
<IMG>.

Libraries were checked on a <NUM> Bioanalyzer (Agilent) using the DNA <NUM> kit (Agilent) and analyzed using the <NUM> Expert software.

Claim 1:
An oligonucleotide primer, comprising:
a <NUM>' arm sequence configured to hybridize to a first end region of a polynucleotide sequence;
a stem-loop sequence comprising a <NUM>' stem sequence, a loop sequence containing a UMI, and a <NUM>' stem sequence; and
a <NUM>' arm sequence configured to hybridize to a second end region of said polynucleotide sequence, wherein said first end region of said polynucleotide sequence is a <NUM>' region of said polynucleotide sequence and said second end region of said polynucleotide sequence is a <NUM>' region of said polynucleotide sequence.