Surface-modified polyacrylonitrile substrates

Abstract: A composition is disclosed herein which comprises a core of a polyacrylonitrile homopolymer or copolymer and a surface of N-haloamides. Also disclosed is a process for the production of said composition.

Description: This application is related to commonly assigned patent applications of Michael Timothy Cooke and Laura Jean Hiscock for Porous Polymer Beads and Process (European patent application No. 89 119 825); and David Arthur Ley, Laura Jean Hiscock and Michael Timothy Cooke for Process for the Preparation of Porous Polymer Beads, (European patent application No. 89 119 823) as well as Michael Timothy Cooke, Larry Stanley Anderson and David Arthur Ley for Surface-hydrated Porous Polyacrylonitrile Substrates, Such as Beads, Derivatives Thereof, Processes for their Preparation and Methods for their Use, (European patent application No. 89 119 824). This invention relates to substrates having a core comprising an acrylonitrile polymer or copolymer thereof and N-haloamide groups on the surface thereof; said surface having no imide or carboxylic groups thereon and a process for their production whereby said haloamide groups were formed from amide groups formed by hydration of surface nitrile groups. One embodiment of the present invention is directed to porous isotropic beads of polyacrylonitrile or a copolymer thereof having N-haloamide groups pendant on the surface thereof. This invention further relates to substrates wherein the aforementioned pendant N-haloamide groups have been further reacted with additional reactants to form functionalized substrates. Said functionalized substrates may be used to form complexes with biological substances, thereby permitting, for example, the separation of said substances from solutions in which they are contained. Substrates produced in accordance with the present invention are useful in various applications including chromatography separation processes. BACKGROUND OF THE INVENTION Rigid non-swellable polymeric materials having neutral, hydrophilic surfaces are useful for many applications. These include chromatography supports, membranes, carriers for immobilized enzymes or immunoassay supports. Hydration of polyacrylonitrile surfaces to form acrylamide groups is well known in the art. U.S. Patent No. 4,110,529 (Stoy), discloses the introduction of reactive groups into the surface layer of beads during coagulation. Example 5 of the Stoy patent discloses the partial hydration of a polyacrylonitrile to 40 percent amide groups and then coagulation to form porous beads. However, beads prepared in this manner are highly swellable in water and contain a substantial amount of byproduct carboxylate groups in addition to the desired amide groups. Thus, the beads are not particularly useful as chromatographic supports. Their tendency to swell results in excessive pressure drops and inconsistent flow rates in chromatographic columns and the presence of carboxylate groups causes non-specific binding in separation processes not involving ion exchange. Problems also arise from the high (up to 40%) amide conversion rate as high conversion to amide groups results in significant losses in bead strength and chromatographic flow due to loss of bead rigidity. Other attempts to convert nitrile groups to amides in the prior art have involved treatment with strong acids or bases. However, both of these techniques generally lead to some formation of surface carboxyl groups. For example, U.S. Patent No. 4,143,203 (Rigopolous) discloses solid particles possessing an impermeable rigid polyacrylonitrile core with a hydrated surface. The surface is hydrated by heating the solid polyacrylonitrile particles in a solution of sulfuric acid at temperatures ranging from 75 to 95°C. However, the beads formed under these conditions are non-porous and also contain a substantial amount of byproduct carboxyl groups. They are therefore not useful in non-ion exchange protein specific chromatographic applications. The surface modification of polyacrylonitrile under basic conditions was studied by K. Ohta et al., Nippon Kagaku Kaishi , 6. 1200 (1985) using surface infrared spectroscopy. After treating polyacrylonitrile films with 5 percent sodium hydroxide solution for 4 hours at 70°C, Ohta reported finding 4.5 percent amide and 5.7 percent carboxylate groups on the surface of the film. Treatment of the film with a solution of 5 percent sodium hydroxide and 15 percent hydrogen peroxide (an aqueous alkaline peroxide reaction) for 4 hours at 70°C reportedly produced 2.1 percent amide and 0.7 percent carboxylate. These treatments are therefore not sufficiently selective. Thus, until recently the state of the art still encountered serious drawbacks to the formation of highly selective non-swellable highly porous acrylonitrile substrates having neutral hydrophilic surfaces. The greater surface area of highly porous beads and the narrow diameter of the polymer structure, makes it critical to accurately control the extent of hydration. Conversion of more than 15 percent of the nitrile groups to amide groups results in significant losses in flow in chromatography separations. It is difficult to accurately control the extent of reaction with acidic hydration. Acidic hydration is also known to have a strong neighboring group effect which generates a "block" polymer structure. A block polymer structure at low conversion can result in non-uniform coverage of the surface. Again, this causes problems with non-specific binding in chromatography applications. A third problem with acidic hydration is the formation of carboxyl and imide groups. The presence of carboxyl groups as previously stated causes undesired ion interactions during size exclusion or affinity chromatography applications. It has been disclosed in a copending application No. 89 119 824.4 that alkaline peroxide hydration of nitriles, with careful control of the solvent utilized, can avoid the aforementioned problems. The reaction selectively converts nitrile groups to amide groups without side reactions to imide or carboxyl groups. By proper selection of the solvent, the reaction can be easily controlled and actually stopped at low conversion. The use of solvent, preferably methanol, allows all of the surfaces of the substrate (as hereinafter defined), to be converted. The process disclosed therein produces an even distribution of amide groups on the surface of the substrate. The rigid nature of the polyacrylonitrile core is minimally effected by this mild treatment and thus, the substrates are non-compressible and substantially non-swellable in water. When used therein, the term "non-compressible" denoted the resistance to hydrostatic pressures in columnar beds of up to about 20.68 MPa (3000 psi.) without collapsing to prevent flow therethrough. A method has now been found to convert substrates, such as the surface treated substrates disclosed in above-discussed copending application No. 89 119 824.4, such that said substrate bears pendant N-chloroamide groups on the surface thereof while the core of the substrate remains unreacted. The substrates so produced are useful as intermediates in the production of various surface treated products which bear functional moieties linked to the core of the substrate through reaction of the pendant N-chloroamide group. From FR-A-2299343 there was known a method for immobilization of an enzyme by reacting the enzyme with a substance containing N-haloamide groups. Said substance may, for example, be one on the basis of acrylonitrile. However, the way of preparing said substance by reacting polyols with acrylonitrile to cyanoethylated intermediates which are then hydrated with hydrogen peroxide and a base to form amides leads to a remarkable carboxylate formation and to a specific structure with relatively long chains bearing the amide group. SUMMARY OF THE INVENTION In accordance with the present invention there are provided substrates comprising: a) a core comprising polyacrylonitrile, or a copolymer of acrylonitrile and at least one comonomer, and b) a surface having evenly distributed thereon haloamide groups, preferably N-chloroamide groups and, optionally, nitrile and/or amide groups. Said surface having no imide or carboxylic groups thereon and said haloamide groups having been formed from amide groups formed by hydration of surface nitrile groups. In a preferred embodiment of the present invention, there is provided a substantially skinless porous bead having a pore-volume of not substantially less than 1.5 ml/g and being substantially isotropic, comprising a core of polyacrylonitrile, or a copolymer thereof, and amide and N-chloroamide groups, and optionally, nitrile groups, evenly distributed over the surface thereof. Also in accordance with the present invention there is provided a process for the preparation of the aforementioned substrates said process comprising a) contacting a core comprising polyacrylonitrile, or a copolymer of acrylonitrile and at least one comonomer, with an alkaline catalyst, a liquid non-solvent for the core polymer having the ability to dissolve the alkaline reagent and peroxide while having only a limited ability to solvate the amide groups as they are formed, a peroxide, and optionally a reducing agent, under reaction conditions and for a time sufficient to convert at least 2.5% of the nitrile groups distributed on the surface of the core to amide groups; b) reacting said amide groups with a halogenating reagent under reaction conditions and for a time sufficient to convert 25 to 100% of the amide groups to N-haloamide groups; and c) recovering the surface-modified substrate. Also disclosed herein is a process for the preparation of the aforementioned polyacrylonitrile porous bead substrates, said process comprising a) forming a suspension in a liquid non-solvent for the polymer or copolymer beads comprising polyacrylonitrile or a copolymer of acrylonitrile and at least one comonomer; b) adding an alkaline catalyst, a peroxide and optionally a reducing agent to said suspension and heating for a time sufficient to convert up to 15 mole percent of the total nitrile groups through hydration to amide groups; c) recovering said beads from said suspension; d) contacting said beads with a halogenating reagent under conditions and for a time sufficient to convert 25 to 100% of said surface amide groups to N-haloamide groups; and e) recovering the surface-modified porous polymer beads. Also disclosed herein is a substrate useful in the recovery and/or isolation of biological material, said substrate comprising a) a core comprising polyacrylonitrile, or a copolymer of acrylonitrile and at least one comonomer, and b) a surface having evenly distributed thereon, i) pendant bioactive ligand groups, said bioactive ligand groups being bound to said surface through linkages derived from bioactive ligands and N-haloamide groups bound to said surface, and optionally, ii) nitrile and/or amide groups. Said surface having no imide or carboxylic groups thereon and said haloamide groups having been formed from amide groups formed by hydration of surface nitrile groups. Further disclosed herein is a process for the production of said substrates useful in the recovery and/or isolation of biological material, said process comprising a) reacting a substrate comprising polyacrylonitrile or a copolymer of acrylonitrile and at least one comonomer with an alkaline catalyst, a liquid non-solvent for the core polymer having the ability to dissolve the alkaline reagent and peroxide while having only a limited ability to solvate the amide groups as they are formed, a peroxide and optionally a reducing agent under reaction conditions and for a time sufficient to convert at least 2.5% of the nitrile groups distributed on the surface of the substrate to amide groups; b) reacting said substrate with a halogenating agent under conditions and for a time sufficient to convert 25 to 100% of said surface amide groups to N-haloamide groups; c) reacting said substrate with a bioactive ligand such that said bioactive ligand is bound to said substrate through a linkage derived from said N-haloamide groups; and d) recovering said substrate. Also disclosed herein are processes for the recovery and/or isolation of biological material using the above-identified compositions of matter. DETAILED DESCRIPTION OF THE INVENTION Substrates comprising polyacrylonitrile homopolymers or copolymers are generally known. For instance, semi-permeable membranes of polyacrylonitrile, are utilized in various chemical separations. Hollow fibers of polyacrylonitrile, such as those marketed by Asahi Medical Company Ltd. under the designation PAN 140, are currently used in kidney dialysis equipment. Porous bead substrates comprising acrylonitrile polymers or copolymers are known to those skilled in the art and utilizable in the practice of the present invention. One method for preparing porous copolymers is described in U.S. Patent No. 4,246,351. A preferred method of preparing porous polyacrylonitrile beads is disclosed in copending European patent applications No. 89 119 823.6 and 89 119 825.1, both claiming priority of November 23, 1988. The thermally induced phase separation process disclosed therein provides microporous beads comprising acrylonitrile polymers or copolymers thereof which are substantially skinless, isotropic, and have a high pore volume. Such porous bead substrates are among the preferred substrates used in the practice of the present invention. Also preferred are polyacrylonitrile substrates such non-porous sheets or films, porous membranes, hollow fibers including porous fibers, monofilaments, acrylic yarns and fibrillated fibers and structures comprised of one or more of these forms. It should be readily apparent that the form of the substrate is not critical to the practice of the invention disclosed herein. As mentioned above, the polyacrylonitrile substrates may comprise acrylonitrile homopolymers or copolymers. Suitable comonomers comprise C₂-C₆ mono-olefins, vinyl aminoaromatics, alkenyl aromatics, vinyl aromatics, vinyl halides, C₁-C₆ alkyl(meth)acrylates, acrylamides, methacrylamides, vinyl pyrrolidones, vinyl pyridine, C₁-C₆ hydroxyesters of alkyl(meth)acrylates, meth(acrylic)acids, acrylomethylpropylsulfonic acids, N-hydroxy-containing C₁-C₆ alkyl(meth)acrylamide, acrylamidomethylpropylsulfonic acids, vinyl acetate, glycidyl (meth)acrylate, glycerol (meth)acrylate, tris(hydroxymethyl)aminomethyl (meth)acrylamide or a mixture thereof. Acrylonitrile copolymers may comprise from, 99 to 20 parts by weight acrylonitrile and from 1 to 80 parts by weight comonomer. It is preferable that the acrylonitrile be present in greater than 90 mole percent and the preferred comonomer comprises methyl acrylate. As used herein in the physical description of the substrates of the present invention, the term "surface" means the interface of the substrates and non-substrate. The term "core" as used herein denotes that portion of the substrate other than its "surface". In the practice of the present invention, the surface of the acrylonitrile substrates is initially hydrated such that the surface bears pendant amide groups. This is accomplished by reacting at least 2.5% of the nitrile groups present on the surface of the substrate with an alkaline peroxide and optionally a reducing agent in a liquid non-solvent for the polymer. The reaction selectively hydrates nitrile groups to amide groups without side reactions to imide or carboxyl groups. The product of this reaction wherein 25 to 100% of the surface nitrile groups have been converted to amide group is hereinafter referred to as "Substrate I". Furthermore, this initial reaction of the present invention is surprisingly easily controlled and conversions of less than 15 mole percent nitrile groups to amide groups are readily obtainable. This reaction is generally disclosed in commonly assigned patent application No. 89 119 824.4 which is referred to above. If beads are utilized as the substrate, the process to produce Substrate I comprises forming a suspension of the beads and a non-solvent for the polymer comprising said beads and the pendant polyacrylamide surface which is formed. It is also contemplated to introduce a catalyst into the suspension. The suspension is then stirred and an alkaline reagent added. The suspension is then heated, a peroxide and preferrably a reducing agent is added while the suspension is stirred, and the reaction is carried out to the desired extent. Suitable peroxides for use in the practice of the present invention include, e.g., hydrogen peroxide, t-butyl hydroperoxide, or mixtures thereof. Especially preferred is hydrogen peroxide. Many alkaline reagents are known to those skilled in the art and are suitable for use in this invention. Alkaline reagents include, e.g., sodium hydroxide, potassium hydroxide, or mixtures thereof. The reducing agent can be any agent capable of reacting with the intermediate hydroperoxide. Especially preferred is dimethyl sulfoxide. Essential to the practice of the present invention is the choice of a suitable solvent for the reaction. The choice and concentration of the components of the solvent system is believed to control the selectivity and extent of the reaction. Although applicants do not wish to be bound by any theory, it is believed that the ability of the solvent system to dissolve the alkaline reagent and peroxide while having only limited ability to solvate the amide groups as they are formed controls the extent of the reaction. Thus by controlling the ratio of the solvent components, the extent of the reaction can be controlled. Preferably, where hydrogen peroxide is the peroxide utilized and dimethyl sulfoxide is the reducing agent, and sodium hydroxide is the alkaline reagent utilized, methanol is employed as solvent with limited ability to solvate the polyacrylacrylamide surface as it is formed. Following the initial reaction wherein surface nitrile groups are selectively converted to amide groups, Substrate I is then removed from contact with the reagents used in its production. The substrate has at least 2.5% of the nitrile groups found on the substrate surface converted to amide groups. Most preferably, in porous substrates 10-15% of the total nitrile groups are converted to amide groups. If porous beads are utilized as the substrate, it is preferred that the beads are annealed prior to their introduction into the suspension with the non-solvent. The annealing step is most preferably carried out as follows: The beads are dried at a temperature of less than 50°C and then heated to 90°-100°C for a period ranging from 30 to 60 minutes. The annealing appears to decrease the reactivity of the bead. Although applicants do not wish to be bound by any single theory, it is postulated that this decrease in bead reactivity occurs by the polymer becoming more ordered and/or decreasing the surface area. Annealing thus affects the nitrile to amide ratio and should therefore be anticipated in the practice of the present invention. Substrate I is then subjected to a second reaction such that 25 to 100% of said amide groups are converted to N-haloamide groups. Preferred embodiments are the formation of N-chloroamide, N-iodoamide, and N-bromoamide groups. The formation of N-chloroamide and N-bromoamide is more preferred. It is important that this conversion be accomplished without the generation of by-products through reaction of the pendant nitrile groups or other unacceptable degradation of the substrate. In the selection of the solvent for the halogenation reaction, the solvent must be inert to the halogenating agent and a non-solvent for the polymer comprising the substrate. Preferred solvents include water, carbon tetrachloride, tetrachloroethane and chlorobenzene. The halogenation reaction involves the use of the amide-bearing substrate with halogenating agents, such as chlorine gas, t-butyl hypochlorite, chloromonoxide, sodium hypochlorite, hypochlorous acid, sodium hypobromite, and mixtures thereof. Typically, the halogenating agents are present in solution in amounts ranging from about 1.0 eq. to about 2.0 eq. based on the amide content of the substrate. Using the formation of N-chloroamides as an example, the chlorinating agents are contacted with Substrate I for sufficient periods to affect the chlorination of the desired portion of the surface amide groups. Typically, contact times range from 0.5 hours to 4.0 hours, preferably from 1 hour to 3 hours when 1.25 eq. solutions are employed. The temperature at which the chlorination reaction is conducted is not critical. Typical reaction temperatures range from 0° to 40°C, preferably from 10° to 30°C. Conversion of pendant amide groups on surface of Substrate I to N-chloroamide groups may be controlled by limiting the reaction time and the concentration of the chlorinating agent. Conversions of 25% to 100% are accomplished while 50-90% conversions are more typically encountered. For porous substrates, an N-chloroamide content of 0.5-3.0 mMole/gram is preferred while those possessing a content of 1.0-2.0 on the identical basis are especially preferred. Following completion of the reaction to the desired level of halogenation, the substrate (which shall hereinafter be referred to as "Substrate II") is removed from contact with the halogenating agent. Optionally, the substrate may be washed to remove remaining quantities of the halogenating agent. Although optional, this step is particularly desirable when porous substrates are used due to their tendency to retain the halogenating agent in their pores. Substrate II, produced through the above-described reaction, comprises a homopolymeric or copolymeric acrylonitrile core and a surface bearing N-haloamide groups. Optionally and directly dependent upon the degree to which the preceding reactions were carried out, the surface of Substrate II may further bear amide nitrile and the comonomer groups that have not undergone reaction. Substrate II is particularly well suited, due to the presence of the pendant N-haloamide groups, to use as an intermediate useful in the production of various final products since the chemistry associated with N-haloamide reactions is widely known. N-haloamides are well known to undergo a Hofmann rearrangement to form isocyanates. For instance, U.S. Patent Nos. 4,301,257, 4,356,289 and 4,357,447 disclose the production of soluble polymeric isocyanates from N-chloroamides. A general discussion of Hofmann rearrangements is further contained in J. March Advanced Organic Chemistry: Reactions, Mechanisms and Structure pp 816-817 McGraw Hill, Inc. 1968. For example, Chemical Reviews , Volume 72 , pp. 457-496 (1972) discusses various reaction schemes which could be employed in the production of numerous products from the isocyanate intermediate formed from Substrate II. For instance, products useful in affinity chromatography, dye affinity chromatography, metal ion affinity, ion exchange, hydrophobic interactions and reverse phase chromatography can be so produced. Of particular interest is the production of products useful in the area of bioseparations and/or affinity chromatography. These products (hereinafter referred to as "Biosubstrates") are produced through the attachment to Substrate II through the pendant surface N-haloamide groups of functional groups (bioligands) which are capable of binding with biological material. The term "binding" as used herein is to be interpreted broadly to encompass not only covalent bonding but also all less powerful interactions, such as electrostatic forces, van der Waals forces, and hydrogen bonding. Production of Biosubstrates through attachment of bioligands to Substrate II may be accomplished directly or through the use of an intermediate bridging group which may facilitate such attachment. For instance, bioligands having pendant H₂N-, HO- or HS-groups may attach directly to Substrate II. Therefore a cationic exchange resin bearing pendant groups may be produced through the direct reaction of Substrate II with H₂N-R-CO₂H where R is, for example, a C₁-C₁₈ alkyl group. Methods of binding bioligands to various substrates and their activation, if necessary, are generally known. For example, the following references contain such disclosure, the contents of which are hereby incorporated by reference. J. Turkova, Affinity Chromatography , Journal of Chromatography Library , Elsevier, Vol. 12 pp. 151-202 (1978). L. Jervis, Syntheses and Separations using Functional Polymers , ed. D.C. Sherrington and P. Hodger, John Wiley and Sons Ltd., pp. 265-304 (1988). Bioligands, as noted above, are chemical and biological moieties capable of binding with biological materials. The term bioligands, as used herein, also includes moieties which are capable of binding with biological material subsequent to their activation. For example, bioligands having pendant groups, such as -CO₂H, -SO₃H, -NR₂ or -NR₃⁺ where R is a C₁₋₆ alkyl group, are capable of binding with biological materials by an ion exchange mode. Bioligands having C₁-C₁₈ alkyl groups can bind with biological materials by hydrophobic interactions. Preferred bioligands are selected from the group consisting of carboxylic acids, sulfonic acids, tertiary amines, quaternary amines, peptides, hormones, enzymes, enzyme cofactors, enzyme substrates, enzyme inhibitors, antigens, antibodies, dyes, pigments, complex metal ions, proteins, nucleic acids, p-aminobenzymidine, polysaccharides, lectins, toxins, antitoxins, polynucleotides, hydrazides and haptens. Preferred biological materials comprise peptides, proteins, hormones, enzymes, antigens, antibodies, nucleic acids, polysaccharides, toxins, antitoxins or polynucleotides. Alternately, Biosubstrates may be produced wherein the bioligand is bound to Substrate II by way of a bridging group. This is a preferred mode for attachment of bioligands derived from biological material. The identity of the bridging group is not critical in the practice of the present invention. However, it must be at least difunctional and be capable of reaction with both the pendant N-haloamide groups of Substrate II and a bioligand without unduly degrading either or unduly interfering with the performance of the Biosubstrate produced. Bridging groups may consist of various difunctional compounds including polyalkylene glycols, such as polyethylene glycols and polypropylene glycols, preferably those having low molecular weights from 62 to 250; monosaccharides, such as fructose, glucose, mannose, ribose, galactose; disaccharides, such as sucrose, maltose, lactose, cellobiose; diamines, such as ethylenediamine, hexamethylenediamine, 1,3-diamino-2-propanol, amino acids, such as glycine, beta-alanine, 6-aminocaproic acid; acyldihydrazides, such as succinic dihydrazide, adipic dihydrazide. The bridging group may have any of the usual chain lengths, being made from difunctional compounds having chain lengths from one to 15 or more atoms between the two reactive functional groups. Bridging groups bearing pendant groups, such as -ROH, -RCO₂H, -RNH₂, RCHO, (CHCHRO) x H, -carbohydrate, require activation and/or reaction with other bioligands prior to their use as Biosubstrates. A bioligand preferably employed in the practice of the present invention is Protein A. Bridging groups and their use in the production of Biosubstrates are generally known. For example, the Turkova and Jervis references noted above disclose their usage. Typically, bridging groups comprise aliphatic, aromatic or cycloaliphatic hydrocarbonaceous groups. They may optionally contain heteroatoms, such as O, N or S. Further, the bridging groups typically contain from 1 to 15 carbon atoms. In the practice of the present invention, the bridging groups are preferably derived from the following reactants: mono-, di- or trialkylene glycols, mono-, di- or trialkyleneamines, lower diols and polyols, alkanolamines and amino acids. Particularly preferred reactants used in the derivation of a bridging group between a bioligand and Substrate II include ethylene glycol, diethylene glycol, triethylene glycol, glycerol, ethylenediamine, diethylenetriamine, ethanolamine, diethanolamine, 3,3'-diamino-N-methylpropylamine, hexanediamine, glycine, beta-alanine, tris(hydroxymethyl)aminomethane, 6-aminocaproic acid and polyoxyethylenediamine. Bridging groups can also be formed through sequential reactions in the presence of Substrate II or they may be preformed prior to the reaction with Substrate II. Particularly preferred as bridging groups in the production of Biosubstrates in the practice of the present invention are the reaction products of: 1) diethylene glycol followed by its reaction with 2-fluoro-1-methylpyridinium-p-toluenesulfonate, and 2) alkylenediamine and succinic anhydride followed by its reaction with N-hydroxysuccinimide, and 3) 6-aminocaproic acid followed by its reaction with N-hydroxysuccinimide. Following the reaction of Substrate II with a reactant to generate a bridging group or Biosubstrate, remaining N-haloamide functionalities present on Substrate II are typically destroyed, preferably such that less than 0.1 mmole of active chlorine per gram substrate remains. This may be accomplished through use of heat, treatment with a reducing agent (such as sodium sulfite) or both. Once produced, Biosubstrates may be utilized in applications where their affinity for and ability to bind with biological material can be utilized. For example, Biosubstrates can be used to isolate biological material from solutions in which it is contained by adding the Biosubstrates to said solutions or by passing said solution over a fixed bed of the Biosubstrate. The Biosubstrate is then isolated from the solution. Optionally, the Biosubstrates can be separated from said solution of biological material to allow for the isolation of the biological material and recycle or reuse of the Biosubstrate. EXAMPLES The following Examples are presented to illustrate the practice of the present invention. They should not be construed however as limitations of the scope of the present invention. PROCEDURE A Five grams of a wet copolymer containing 99 mole percent acrylonitrile and 1 mole percent of methyl acrylate (1:1 copolymer:water by weight) were ground with 5 grams of urea and 30 grams of dimethylsulfone to form a powdered mixture. The mixture was placed in a 1 liter flask containing 100 ml of mineral oil heated to 160°C. The mixture was stirred until two liquid phases were present, one phase being a homogeneous polymer solution, the other mineral oil. Rapid stirring of the mixture with an overhead paddle stirrer gave a suspension consisting of droplets of the hot (about 120°C) polymer solution in mineral oil. The droplets were cooled by transferring the suspension via a canula to a second stirred mixture consisting of 500 ml of mineral oil, 6 grams of dimethylsulfone, and 1 gram of urea kept at 70°C. The droplets solidified upon contacting the cooler mineral oil. The mixture was cooled with stirring to room temperature, then diluted with methylene chloride to reduce the viscosity of the oil. The droplets were collected on a Buchner funnel and washed with methylene chloride, then the solvent was extracted with 200 ml of acetone for 1.5 hours at room temperature. The resulting beads were examined by scanning electron microscopy and seen to be highly porous, with relatively uniform pore diameter of about 0.5 µm (microns). The pores extended through the outer surfaces of the beads. The beads ranged in size from 10µm (microns) to a few millimeters in diameter. Another detailed example of preparing these porous polymer beads is as follows: Two-hundred eighty-eight grams of dimethylsulfone, 12 grams of acrylonitrile copolymer consisting of a 99:1 mole ratio acrylonitrile: methyl acrylate, and 100 ml of propylene glycol were combined and placed in a Parr reactor equipped with a magnetically driven stirrer and dip leg. The reactor was heated to 140°C to form a homogeneous solution. The solution was forced through heated (140°C) lines and an atomization nozzle (Lechler Co. full cone "center jet" nozzle, 1.17 cm (0.46 in.) diameter orifice) using 1.034 MPa (150 psig) nitrogen pressure. The nozzle was mounted 7.6 cm (3 inches) over 3 liters of stirred mineral oil or 10.1 cm (4 inches) over 4 liters of stirred heptane to quench the liquid droplets. The solidified droplets were washed with heptane to remove mineral oil, dried and extracted for one hour with 3 liters of 85 - 90°C water to produce microporous beads. Pore sizes ranged from 0.05 to 1.5 µm (microns) and the majority of the beads are between 25 to 150 µm (microns). The following examples illustrate the production of Substrate I which bears pendant amide groups. EXAMPLE 1A A suspension of 5 grams of dry annealed polyacrylonitrile beads (45-90 µm (microns), 94.5 mmoles) in 115 ml of methanol, 5 ml of water, and 4 ml of dimethylsulfoxide (56.4 mmoles) were stirred under a nitrogen purge. After ten minutes of purging, 2.4 ml of 2N aqueous sodium hydroxide (4.8 mmoles) were added to the suspension and the suspension heated to 35°C. Hydrogen peroxide, 4.9 ml of a 30 percent solution (47.9 mmoles) was added over 10 minutes. The reaction mixture was stirred at 35°C for three hours. After 3 hours, 2.4 ml of 2N hydrochloric acid (4.8 mmoles) was added and the reaction mixture was stirred for one minute and filtered. The beads were washed with O.1N aqueous hydrochloric acid, water, methanol and then dried. The amide content of the beads was determined to be 9.7 percent by infrared analysis. The following Examples illustrate the production of Substrate I which bears pendant amide groups as well as Biosubstrates made therefrom. EXAMPLE 1B Dry annealed polyacrylonitrile hollow fibers, 0.5g, were mixed with 11.5 ml of methanol, 0.5g of water, 0.24 ml of 2N aqueous sodium hydroxide solution, and 0.4 ml of dimethyl sulfoxide. The mixture was heated to 35°C, and 0.49 ml of a 30% hydrogen peroxide solution was added. After standing at room temperature for 3 hrs., the reaction mixture was filtered. The fibers were washed with water and methanol and vacuum dried (40°C). The amide content of the fibers was determined to be 14.1% by infrared analysis. EXAMPLE 1C The procedure of Example 1B was followed except that 0.50 g of a non-annealed fibrillated fiber sheet was used with 1.47 ml of 30 percent hydrogen peroxide solution was used, and the fiber was annealed before the reaction. IR analysis showed that the amide content of the MAP fibrillated fiber product was about 2%. EXAMPLE 1D The reaction procedure of Example 1B was followed except that 0.52g of a nonporous film made from a 89.5: 10.5 acrylonitrile:methyl acrylate film was used and the film was not annealed. Contact angle for water was 42°; initial film had a water contact angle of 63°. The following Examples illustrate the production of Substrate II which bears pendant N-chloroamide groups as well as the Biosubstrates made therefrom. EXAMPLE 2 The product of Example 1A, 3g, was mixed with 78 ml of water. To this suspension was added 0.471g of chlorine gas. The addition time of the chlorine was 11 minutes. The reaction mixture was stirred at room temperature for 2 hrs. After 2 hrs. the reaction mixture was filtered. The beads were washed with water and then vacuum dried (40°C). Iodometric titration showed that the beads contained 1.40 mmole/g of active chlorine corresponding to ca. 80% chlorination of the amide groups on the beads. EXAMPLE 3 A solution of 130 ml of diethylene glycol (DEG) and 6.3 ml of 2N aq. sodium hydroxide was heated to 40°C. To this solution was added 5g of the product of Example 2. The reaction mixture was stirred at ca. 40°C for 2 hrs. After two hrs., the reaction mixture was filtered. The beads were washed with water and then vacuum dried (40°C). Infrared spectroscopy confirmed that DEG had been reacted with said beads through a Hofmann rearrangement. EXAMPLE 4 The procedure of Example 3 was followed, except that 100 ml of ethylene glycol (EG), 3.3 ml of 2N aq. sodium hydroxide and 2g of the product of Example 2 were used for the reaction. Infrared spectroscopy confirmed that EG had been reacted with said beads through a Hofmann rearrangement. EXAMPLE 5 The procedure of Example 3 was followed, except that 235 ml of triethylene glycol (TEG), 3.8 ml of 2N aq. sodium hydroxide and 3.5g of the product of Example 2 were used. Infrared spectroscopy confirmed that TEG had been reacted with said beads through a Hofmann rearrangement. EXAMPLE 6 The procedure of Example 3 was followed except that 100 ml of methanol, 2.3 ml of 2N aq. sodium hydroxide and 2g of the product of Example 2 were used. Infrared spectroscopy confirmed that methanol had been reacted with said beads through a Hofmann rearrangement. EXAMPLE 7 The procedure of Example 3 was followed except that 65 ml of glycerol, 2.3 ml of 2N aq. sodium hydroxide, and 2g of the product of Example 2 were used, and 4 ml of water was added to the glycerol solution prior to the addition of the beads. Infrared spectroscopy confirmed that glycerol had been reacted with said beads through a Hofmann rearrangement. EXAMPLE 8 A solution of 90 ml of ethylenediamine (EDA) and 3 ml of water was heated to 40°C. To this solution was added 2g of the product of Example 2. The reaction mixture was stirred at 40°C for 2 hrs. After two hrs., the mixture was filtered. The beads were washed with water and then vacuum dried (40°C). Infrared spectroscopy confirmed that EDA had been reacted with said beads through a Hofmann rearrangement. EXAMPLE 9 The procedure of Example 8 was followed except that 100 ml of diethylenetriamine (DETA), 3 ml of water, and 2g of the product of Example 2 were used. Infrared spectroscopy confirmed that DETA had been reacted with said beads through a Hofmann rearrangement. EXAMPLE 10 The procedure of Example 8 was followed except that 100 ml of ethanolamine (EA), 3 ml of water, and 2g of the product of Example 2 were used. Infrared spectroscopy confirmed that EA had been reacted with said beads through a Hofmann rearrangement. EXAMPLE 11 The procedure of Example 8 was followed except that 75 ml of diethanolamine (DEA), 50 ml of water, and 2g of the product of Example 2 were used. Infrared spectroscopy confirmed that DEA had been reacted with said beads through a Hofmann rearrangement. EXAMPLE 12 The procedure of Example 8 was followed except that 75 ml of triethanolamine (TEA), 50 ml of water, and 2g of the product of Example 2 were used. Infrared spectroscopy confirmed that TEA had been reacted with said beads through a Hofmann rearrangement. EXAMPLE 13 The procedure of Example 8 was followed except that 98 ml of propylamine (PA), 2.5 ml of water, and 2g of the product of Example 2 were used. Infrared spectroscopy confirmed that PA had been reacted with said beads through a Hofmann rearrangement. EXAMPLE 14 The procedure of Example 8 was followed except that 100 ml of diethylamine (DEA), 3 ml of water and 2g of the product of Example 2 were used. Infrared spectroscopy confirmed that DEA had been reacted with said beads through a Hofmann rearrangement. EXAMPLE 15 The procedure of Example 8 was followed except that 1100 ml of 3,3′-diamino-N-methylpropylamine, 28 ml of water, and 22g of the product of Example 2 were used. Infrared spectroscopy confirmed that 3,3′-diamino-N-methylpropylamine had been reacted with said beads through a Hofmann rearrangement. EXAMPLE 16 A mixture of 65g of tris(hydroxymethyl)aminomethane (Tris) and 65g of water was heated in an oil bath; the mixture turned to a clear solution after the temperature of the mixture reached 55°C. The solution cooled to 40°C, and to this solution was added 2g of the product of Example 2. The suspension was stirred at room temperature for two hrs. and then filtered. The beads were washed with water and vacuum dried (40°C) Infrared spectroscopy confirmed that tris(hydroxymethyl)aminomethane (Tris) had been reacted with said beads through a Hofmann rearrangement. EXAMPLE 17 The procedure of Example 8 was followed except that 100 ml of 3-diethylaminopropylamine, 2.0 ml of water and 2.5g of the product from Example 2 were used, and the reaction mixture was stirred at 40°C for 3 hours. Potentiometric titration of the beads using aq. hydrochloric acid revealed that the beads contained 0.86 meq/g of the amino group. Infrared spectroscopy confirmed that diethylaminopropylamine had been reacted with said beads through a Hofmann rearrangement. EXAMPLE 18 To 260 ml of a 0.2N aq. sodium hydroxide solution was added 1Og of the product of Example 2. The suspension was stirred at room temperature for 3 hrs. and then filtered. The beads were washed with water and vacuum dried (40°C). Potentiometric titration using aq. hydrochloric acid showed that the beads contained 0.33 meq/g of the carboxylic group. EXAMPLE 19 A solution containing 50g of dextran (mol. wt. 15,000) and 50 ml of water was heated to 40°C. To this solution was added 10g of the product of Example 2 and 5 ml of 2N aq. sodium hydroxide solution. The suspension was stirred at 42°C for 3 hrs. and then filtered. The beads were washed with water and vacuum dried. Analysis using anthrone method ( Anal . Chem . 25 , 1656, (1953)) showed that the beads contained 3% by wt. dextran. Infrared spectroscopy confirmed that said functional groups had been reacted with said beads through a Hofmann arrangement. EXAMPLE 20 The procedure of Example 8 was followed except that 130 ml of polyoxyethylenediamine (Jeffamine EDR-148), 3 ml of water and 5g of the product of Example 2 were used. Infrared spectroscopy confirmed that poloxyethylenediamine had been reacted with said beads through a Hofmann rearrangement. EXAMPLE 21 A solution of 117 ml of decylamine and 2.7 ml of water was heated to 40°C. To this solution was added 4.5g of product of Example 2. The suspension was stirred at 40°C for 2 hrs. and then filtered. The beads were washed with acetone and hexanes and vacuum dried (40°C). Infrared spectroscopy confirmed that decylamine had been reacted with said beads through a Hofmann rearrangement. EXAMPLE 22 A mixture of 1Og of octadecylamine and 15 ml of hexadecane was heated in an oil bath. The mixture turned to a clear solution when the temperature of the mixture reached 60°C. To this solution was added 0.6 ml of water and 1.25g of the product of Example 2. The mixture was stirred at 62°C for 75 minutes and then filtered. The beads were washed with heptane and vacuum dried (40°C). Infrared spectroscopy confirmed that octadecylamine had been reacted with said beads through a Hofmann rearrangement. EXAMPLE 23 A solution of 75 ml of dioxane (dried over 3A molecular sieving) and 10.5g of carbonyldiimidazole was purged with nitrogen. The solution was then heated to 35°C, and to this solution was added 3.5g of the product of Example 3. The suspension was stirred at 35°C under nitrogen atmosphere for 1.5 hrs. and then filtered. The beads were washed with acetone, cold water, THF and acetone and vacuum dried at room temperature. Infrared spectroscopy confirmed that carbonyldiimidazole had been reacted with said beads. EXAMPLE 24 A suspension of 10g of ethylenediamine urea beads (the product of Example 8), and 90 ml of O.1N sodium chloride was immersed in a 4°C ice bath. Powdered succinic anhydride (40g) was slowly added with constant stirring over 2 hrs. The pH was maintained at 6.0 with the addition of 5N NaOH and the temperature was kept between 4 o C and 1O°C. After the succinic anhydride addition, the temperature was maintained at 4°C and the pH was kept at 6.0 for an additional 4 hrs. The beads were collected, washed with 1.ON hydrochloric acid, water, and methanol, and then vacuum dried. Titration results showed 145 micromoles of carboxyl groups/ml of beads. EXAMPLE 25 Succinylated ethylenediamine urea beads (prepared as in Example 24), 2.0 mls, containing 114 micromoles of carboxyl groups/ml, were dehydrated in p-dioxane. The beads were collected and added to 5 ml of dry p-dioxane. N-Hydroxysuccinimide, 500 micromoles, was added followed by 500 micromoles of dicyclohexylcarbodiimide. Non-solvents for acrylonitrile polymers or copolymers may comprise any liquid medium which is immiscible therewith. These were tumbled overnight, collected, and washed with dry p-dioxane and methanol. The activation density was 37 micromoles/ml (determined by the method of T. Miron and M. Wilchek, Analytical Biochemistry, 126, 433-435 (1982)). The following Examples illustrate the attachment of bioligands or other functional groups to Substrate II through various bridging groups. EXAMPLE 26 Succinylated ethylenediamine urea beads (prepared as in Example 24), 0.25g, containing 114 micromoles of carboxyl groups/ml, were added to 2.5 ml of O.1N NaCl. Ethylenediamine dihydrochloride, 0.45g, was added and the pH was adjusted to 4.7 with O.1N NaOH. 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride (EDAC), 0.049, was added, and this was tumbled 24 hrs. at room temperature while maintaining the pH at 4.7. The beads were collected, washed with O.1N HCl, water, and methanol, and then vacuum dried. These beads contained 98 moles amine/ml (determined by the method of G. Antoni, et al ., Analytical Biochemistry , 129, 60-63 (1983)). EXAMPLE 27 The dehydrated product of Example 3, 10 mls, was added to 10 ml of dry acetonitrile containing 5500 micromoles of 4-dimethylaminopyridine (DMAP). 2-Fluoro-1-methyl-pyridinium toluene-4-sulfonate (FMP) 5,000 micromoles, in dry acetonitrile, 25 ml, was added directly to the bead mixture. This was tumbled 2 hrs. at room temperature. The beads were washed 1x 100 ml acetonitrile, 2x 100 ml acetone, and stored at 4°C in 30 ml of dry acetone. The beads contained 112 micromoles of activated hydroxyl groups/ml, as assayed by the amount of 1-methyl-2-pyridone released when the beads were tumbled 24 hr. at room temperature in 0.2N sodium hydroxide (see T. Ngo, Bio/Technology, Vol. 4, 134-137 (1986), for the spectrophotometric assay procedure). The product produced was identified as a polymer containing 1-methyl-2-pyridoxal toluene-4-sulfonate (MPTS) groups. EXAMPLE 28 The procedure of Example 27 was followed except that 3.5 ml of the product of Example 12 was reacted with 1925 micromoles of DMAP in 3.5 ml of acetonitrile, and 1750 micromoles of FMP in 8.9 ml of acetonitrile. The density of activation was 27.3 micromoles/ml. The product produced was identified as a polymer containing MPTS groups. EXAMPLE 29 The procedure of Example 27 was followed except that 5.5 ml of the product of Example 50 was reacted with 3025 micromoles of DMAP in 5.5 ml of acetonitrile, and 2750 micromoles of FMP in 13.8 ml of acetonitrile. The density of activation was 155 micromoles/ml. The product produced was identified as a polymer containing MPTS groups. EXAMPLE 30 The procedure of Example 27 was followed except that 2.0 ml of the product of Example 16 was reacted with 1100 micromoles of DMAP in 2.0 ml of acetonitrile, and 1000 micromoles of FMP in 5.0 ml of acetonitrile. The density of activation was 18.8 micromoles/ml. The product produced was identified as a polymer containing MPTS groups. EXAMPLE 31 The procedure of Example 30 was followed except that a solution of 40% dimethylsulfoxide, 60% acetonitrile was used in place of acetonitrile. The density of activation was 28.5 micromoles/ml. The product produced was identified as a polymer containing MPTS groups. EXAMPLE 32 The procedure of Example 27 was followed except 10 ml of the product of Example 7 was used. The density of activation was 23.7 micromoles/ml. The product produced was identified as a polymer containing MPTS groups. EXAMPLE 33 The procedure of Example 27 was followed except 10 ml of the product of Example 5 was used. The density of activation was 70.1 micromoles/ml. The product produced was identified as a polymer containing MPTS groups. EXAMPLE 34 The dehydrated product of Example 3, 6 ml, was added to 18 ml of dry acetone. p-Nitrophenylchloroformate, 6000 micromoles, was added and the mixture was immersed in a 4°C ice bath. DMAP, 7200 micromoles in 10 ml of dry acetone, was added dropwise, and the contents were tumbled for 1 hr. at 4°C. The beads were collected and washed with cold acetone, 5% acetic acid in dioxane, methanol, and isopropanol, and stored at 4°C in isopropanol. The density of activation was 20.1 micromoles/ml (determined by the method of T. Miron and M. Wilchek, Biochemistry International , Vol. 4 , No. 6, 629-635 (1982)). The product produced was identified as a polymer containing p-nitrophenyl formate groups. EXAMPLE 35 The dehydrated product of Example 3, 2.5 ml, was added to 4 ml of dry acetone containing 2500 micromoles of N,N′-disuccinimidyl carbonate. A solution of 4250 micromoles of DMAP in 5 ml of acetone was slowly added. The suspension was tumbled for 1 hr. at 4°C. The beads were collected and washed with cold acetone, 5% acetic acid in dioxane, methanol, and isopropanol. The activated beads were stored in 4°C isopropanol. The density of activation was 28.5 micromoles/ml (determined by the method of M. Wilchek and T. Miron, Applied Biochemistry and Biotechnology , Vol. 11 , 191-193 (1985)). The product produced was identified as a polymer containing active hydroxy succinimide carbonate (HSC) groups. EXAMPLE 36 The procedure of Example 35 was followed except the product of Example 5 was used. The density of activation was 25.6 micromoles/ml. The product produced was identified as a polymer containing active HSC groups. EXAMPLE 37 The product of Example 27, 0.50 ml, was washed 3x1O ml water, 1x3 ml 0.05N sodium carbonate/sodium bicarbonate, pH 8.5 (coupling buffer). The coupling buffer, 1.20 ml, containing 50 mg of bovine serum albumin (BSA) was added to the beads. After tumbling for 24 hrs. at room temperature, the beads were washed with 4x1O ml 1.ON NaCl, and 3x1O ml water. The beads coupled 8.1 mg BSA/ml (determined from protein concentration in combined washings, using the Pierce BCA Protein Assay). The product produced was identified as a polymer with immobilized BSA. EXAMPLE 38 The procedure of Example 37 was followed except the product of Example 28 was used. The beads coupled 5.8 mg BSA/ml. The product produced was identified as a polymer with immobilized BSA. EXAMPLE 39 The product of Example 35, 0.50 ml, was washed with 4°C water and 4°C O.1N phosphate buffer, pH = 7.5 (coupling buffer). Bovine serum albumin, 50 mg, in 1.20 ml of coupling buffer was added. This was tumbled at 4°C for 24 hrs. The beads were washed with 4x40 ml 1.ON NaCl, 3x1O ml water. The beads coupled 5.5 mg BSA/ml (determined from the protein concentration in the combined washings, using the Bio-Rad Protein Assay). EXAMPLE 40 The procedure of Example 37 was followed except that the product of Example 33 (prepared with a lower density of activation of 16 micromoles/ml), 2 ml was used. Cytochrome C, 12.2 mg, in 2.7 mls of 0.2N NaHC0₃ pH = 9.0, was added to the beads. These beads coupled 1.5 mg Cytochrome C/ml (determined from Bio-Rad Protein Assay). EXAMPLE 41 The procedure of Example 40 was followed except the product of Example 27 (prepared with a lower degree of activation of 25 micromoles/ml) was used. The beads coupled 2.9 mg Cytochrome C/ml (determined by the Bio-Rad Protein Assay). The following Examples illustrate the practice of the present invention wherein substrates other than beads are utilized. EXAMPLE 42 The product of Example 1B, 0.24g, was mixed with 14 ml of water. To this mixture was added 0.066g of chlorine in 4 minutes. After standing at room temperature for 1.5 hrs., the reaction mixture was filtered. The fibers were washed with water and vacuum dried (40°C) Iodometric titration showed that the fibers contained 1.92 mmole/g of active chlorine. EXAMPLE 43 A solution of 5 ml of diethylene glycol and 0.2 ml of 2N aqueous sodium hydroxide solution was heated to 40°C. To this solution was added 0.12g of the product of Example 42. The reaction mixture was heated at 42°C for 2 hrs. and then filtered. The fibers were washed with water and vacuum dried. Infrared spectroscopy revealed that diethylene glycol had reacted with the fibers by way of a Hofmann rearrangement. EXAMPLE 44 The product of Example 1C, 0.41g, was mixed with a solution of 20 ml of water and O.1Og of chlorine. After standing at room temperature for 2hrs., the reaction mixture was decanted. The fiber was washed with water and vacuum dried (40°C). Iodometric titration showed that the fiber contained 0.70 mmole/g of active chlorine. EXAMPLE 45 A solution of 15 ml of DEG and 0.4 ml of 2N aqueous sodium hydroxide solution was heated to 40°C. To this solution was added 0.3g of the product of Example 44. After standing at 40°C for 3 hrs., the reaction mixture was decanted, and the fiber was washed with water and methanol and vacuum dried (40°C). Infrared spectroscopy revealed that diethylene glycol had reacted with the fibers by way of a Hofmann rearrangement. EXAMPLE 46 The procedure of Example 44 was followed and the product of Example 1D, 0.38g, was used for the reaction to produce a nonporous acrylonitrile copolymer film having pendant N-chloroamide groups therefrom. EXAMPLE 47 A mixture of 0.05g of the product of Example 46, 10 ml of decylamine, and 0.2 ml of water was heated at 40°C for 3 hrs. The reaction mixture was then decanted. The film was washed with heptane several times and vacuum dried (room temperature). Water contact angle for the film was 107°. EXAMPLE 48 A mixture of 5g of tri(hydroxymethyl)aminomethane and 5g of water was heated to 55°C, and the mixture turned to a clear solution. The solution cooled to 50°C, and to this solution was added 0.12g of the product of Example 46. After standing at 43°C for 3 hrs., the reaction mixture was decanted. The film was washed with water and methanol and air dried. The water contact angle was 54°. EXAMPLE 49 The procedure of Example 27 was followed except that 0.0585g of the product of Example 43 was reacted with 320 micromole of DMAP in 0.582 ml of dry acetonitrile, and 290 micromoles of FMP in 1.450 ml of dry acetonitrile. The density of activation of the resulting product was 241.0 micromole/g. EXAMPLE 50 The procedure of Example 8 was followed except 26 ml of N-methyldiethanolamine, 0.70 ml of water, and 1.Og of the product of Example 2 were used. Infrared spectroscopy confirmed that the N-methyldiethanolamine had reacted with the substrate through a Hofmann rearrangement. EXAMPLE 51 The procedure of Example 8 was followed except that 3g of the product of Example 2, 100 ml of N,N-diethylethylenediamine (DEAE) and 2 ml of water were used and the reaction mixture was stirred at 45°C for 3 hrs. Infrared spectroscopy confirmed that DEAE had been reacted with said beads through a Hofmann rearrangement. Potentiometric titration using aqueous hydrochloric acid showed that the beads contained 1.03 meq/g of the amino group. EXAMPLE 52 A mixture of 52g of glycine and 52 ml of 35% (w/w) aqueous sodium hydroxide was heated to 35°C and a clear solution was obtained. The this solution was added 4g of the product of Example 2. The suspension beads were washed with 0.1N aq. sodium hydroxide, and water and vacuum dried. Infrared spectroscopy confirmed that glycine had reacted with said beads through a Hofmann rearrangement. Potentiometric titration showed that the was stirred at 40°C for 3 hrs and then filtered. The beads contained 1.20 meq/g of the carboxylate group. EXAMPLE 53 The procedure of Example 52 was followed except that 3g of the product of Example 2, 39g of beta-alanine and 35 ml of 35% (w/w) aq. sodium hydroxide were used. Infrared spectroscopy confirmed that the beta-alanine had reacted with said beads through a Hofmann rearrangement. Potentiometric titration showed that the beads contained 1.23 meq/g of the carboxylate group. EXAMPLE 54 The procedure of Example 52 was followed except that 3g of the product of Example 2, 42g of 6-aminocaproic acid, 23ml of 35% (w/w) aq. sodium hydroxide were used, and before heating to 35°C, 16 ml of water was added to the mixture of 6-aminocaproic acid and 35% aq. sodium hydroxide. Infrared spectroscopy confirmed that the 6-aminocaproic acid had reacted with said beads through a Hofmann arrangement. Potentiometric titration showed that the beads contained 1.09 meq/g of the carboxylate group. EXAMPLE 55 The product of Example 45, 0.10g, was washed 3x40 ml dry acetone, 5x40 ml dry acetonitrile, and the solvent was removed. The fibrillated fibers were added to 8 ml of dry acetonitrile containing 0.07g of 4-dimethylaminopyridine. 2-Fluoro-1-methyl-pryidinium p-toluene-sulfonate (FMP), 0.14g, in 2.6 ml of dry acetonitrile was added all at once and the solution was tumbled for 2 hours at room temperature. The fibers were collected and washed 1x50 ml acetonitrile, and 2x100 ml acetone. The fibers contain 127 umoles of activated hydroxyl groups/gram, when assayed with 0.2N sodium hydroxide (see Example 27 for assay procedure). The fiber product was demonstrated to contain MPTS groups. The following Examples illustrate the use of various Biosubstrates produced in accordance with the present invention. EXAMPLE 56 The product of Example 55, 0.6g, was washed 3x13 ml distilled water, and 1.13 ml 0.05N sodium carbonate, pH = 8.5 (coupling buffer). The buffer was removed and 6.4 ml of coupling buffer containing 100 mg of bovine serum albumin (BSA) was added. This was tumbled at room temperature for 3 hours, and then at 4°C for 2 days. The fibers were washed 3x100 ml of coupling buffer and 4x100 ml of 1.0N sodium chloride. The fibers coupled 4.44 mg BSA (7.3 mg BSA/g of fiber). This was determined by performing the Pierce BCA* Protein Assay directly on the fiber. EXAMPLE 57 The product of Example 27, 1 ml (prepared with 31 micromoles activated hydroxyl groups/ml of bead), was washed 3x10ml water, 1x10 ml 0.05N sodium carbonate, pH = 8.5 (coupling buffer). The coupling buffer was removed and 1 ml of degassed coupling buffer containing 8 mg of protein A was added. This was tumbled 24 hours at room temperature and then 24 hours at 4°C. The beads were washed with 3 ml of 0.5 N NaCl in coupling buffer and then 4x10 ml (0.001 N NaOH, 0.1N LiCl in a 75/25 (v/v) methanol/water) solution over 0.5 hour. After washing 1x10 ml 0.01N sodium acetate, pH = 4.5, the beads were stored at 4°C in 0.01N Tris-HCl, 0.1% sodium azide, pH = 8.5. The beads were shown to have coupled Protein A. EXAMPLE 58 The product of Example 55, 1.2g, was reacted with 8 mg of Protein A following the procedure of Example 57, except that a 5 fold solution volume was used to allow complete wetting of the fibers. The beads were shown to have coupled Protein A. EXAMPLE 59 The product of Example 57, (1ml) was suspended in phosphate buffered saline (PBS), (0.10M sodium phosphate, 0.9% sodium chloride, 0.01% sodium aside, pH = 7.4), and packed into a 5 ml chromatography column. The beads were washed with 5ml of a 0.1% acetic acid in 10% methanol buffer (Regeneration Buffer) and then 15 ml of PBS (Binding Buffer), at flow rates of 40 ml/hr. Normal human serum (NHS) was diluted 1 part NHS to 2 parts binding buffer and filtered. Diluted NHS 12 ml, was gravity fed through the column. After washing the beads with 20 ml of binding buffer, purified IgG was eluted with a 0.1N glycine, pH = 2.8 buffer. Using the extinction coefficient at 280 nm of a 1% solution of human IgG of 13.5, the binding capacity of the beads was shown to be about 27.0 mg IgG/ml of beads. EXAMPLE 60 The fibrillated fiber product of Example 58, was cut into three 47.6 mm (1 7/8") circles, (0.36 g), and was packed into a cartridge (Millipore). The fibers were checked for IgG binding following the procedure of Example 59. The binding capacity was shown to be about 9.1 mg IgG/gram of fibers. EXAMPLE 61 The procedure of Example 8 was followed except that 15 grams of 1,6-hexanediamine, 13.7g of diethylene glycol, 1.0 ml of water, and 1.0g of the product of Example 2 were used. These beads contained 169 micromoles of amine/ml of bead when determined by the method of Example 26. EXAMPLE 62 Following the procedure of H.J. Bohme, et al., (J. of Chromatography, 69 (1972) 209-214), 0.4g of Cibacron Blue F3G-A (Sigma) in 12 ml of water was added to 2g of the product of Example 3 in 70 ml of 60°C water. This was stirred for 1/2 hour and then 9g of sodium chloride was added. This was heated to 80°C and then 0.8g of sodium carbonate was added. This was stirred for 2 hours, and then the beads were collected and washed with water and methanol to give dark blue beads. It was determined that the Cibacron Blue dye had been bonded to the beads through a urethane-DEG linkage. COMPARATIVE EXAMPLE Underivatized fibrillated fiber, 0.5g, was washed five times with 10 ml solutions of 1.0N NaCl, DI water and 3x10 ml phosphate buffered saline (PBS), (0.01 M sodium phosphate, 0.9% sodium chloride, 0.01% sodium aside, pH = 7.4). PBS, 10 ml, containing 100 mg of BSA was contacted with the fibers and this was tumbled at room temperature for 1 hour. The fibers were washed with 4x10 ml distilled water and with 10x10 ml of PBS. The assay for protein using the Pierce BCA* Protein Assay Reagent directly on the fiber showed 1.2 mg of BSA non-specifically bound to the fiber (2.4 mg BSA/gram of fiber). EXAMPLE 63 The procedure of the Comparative Example was followed except 0.5g of the product of Example 45 was used. This fiber showed no non-specifically bound BSA. EXAMPLE 64 A 1.13g sample of spun acrylic yarn was treated as disclosed in Example 1. The examination of the surface by ESCA revealed the presence of amide groups. EXAMPLE 65 The product of Example 27, 1.0 ml, prepared with 33 micromoles of activated hydroxyl groups/ml, was coupled with BSA following the procedure of Example 37, except that 25 mg of BSA was added/ml of beads. The amount of coupling was 3.5 mg BSA/ml of beads. EXAMPLE 66 The procedure of Example 65 was repeated, except that a 40% Ethanol, 60% coupling buffer (v/v), was used. The amount of coupling was 13.3 mg BSA/ml of beads.

Claims: A surface modified polyacrylonitrile substrate comprising: (a) a core comprising polyacrylonitrile or a copolymer of acrylonitrile and at least one comonomer, and (b) a surface having evenly distributed thereon (i) N-haloamide groups or pendant bioactive ligand groups, said bioactive ligand groups being bound to said surface through linkages derived from the reaction of bioactive ligands and said N-haloamide groups bound to said surface, and, optionally, (ii) nitrile and/or amide groups, said surface having no imide or carboxylic groups thereon and said haloamide groups having been formed from amide groups formed by hydration of surface nitrile groups. The substrate of Claim 1 wherein said core comprises a copolymer of polyacrylonitrile wherein the acrylonitrile content of said core ranges from 20 to 99 parts by weight, and preferably is greater than 90 mol percent. The substrate of Claim 1 wherein said comonomer is selected from the group consisting of C₂-C₆ mono-olefins, vinyl aminoaromatics, alkenyl aromatics, vinyl aromatics, vinyl halides, C₂-C₆ alkyl(meth)acrylates, acrylamides, methacrylamides, vinyl pyrrolidones, vinyl pyridine, C₁-C₆ hydroxyesters of alkyl(meth)acrylates, meth(acrylic)acids, acrylomethylpropylsulfonic acids, N-hydroxy-containing C₁-C₆ alkyl(meth)acrylamide, acrylamidomethylpropylsulfonic acids, vinyl acetate, glycidyl(meth)acrylate, glycerol(meth)acrylate, tris(hydroxymethyl)aminomethyl(meth)acrylamide and mixtures thereof. The substrate of Claim 1 wherein said core comprises a copolymer of acrylonitrile and methyl acrylate wherein said acrylonitrile comprises at least 90 mol percent of said copolymer. The substrate of Claim 1 wherein said substrate comprises porous beads, non-porous sheets, porous membranes, hollow non-porous fibers, hollow porous fibers, monofilaments, yarns, fibrillated fibers, or combinations thereof. The substrate of Claim 1 wherein said substrate comprises porous beads. The substrate of Claim 1 wherein said substrate comprises fibrillated fiber. The substrate of Claim 1 wherein said N-haloamide groups are selected from the group consisting of N-chloroamide, N-iodoamide and N-bromoamide groups, or preferably of N-chloroamide and N-bromoamide groups. The substrate of Claim 1 wherein said bioligand is selected from the group consisting of carboxylic acids, sulfonic acids, tertiary amines, quaternary amines, peptides, hormones, enzymes, enzyme cofactors, enzyme substrates, enzyme inhibitors, antigens, antibodies, dyes, pigments, complex metal ions, proteins, nucleic acids, p-aminobenzamidine, polysaccharides, lectins, toxins, antitoxins, polynucleotides, hydrazides and haptens. The substrate of Claim 1 wherein said bond of said bioligand and said surface further comprises aa bridging group. The substrate of Claim 10 wherein said bridging group is selected from the group consisting of C₁ to C₁₅ aliphatic, aromatic, cycloaliphatic groups which optionally contain heteroatoms, such as O, N or S. The substrate of Claim 10 wherein said bridging group is selected from the group consisting of ethylene glycol, diethylene glycol, triethylene glycol, glycerol, ethylenediamine, diethylenetriamine, ethanolamine, diethanolamine, 3,3'diamino-N-methyl-propylamine, hexanediamine, glycine, beta-alanine, tris(hydroxymethyl)aminomethane, 6-aminocaproic acid and polyoxyethylenediamine. A process for the preparation of surface-modified acrylonitrile polymer substrates, preferably substrates useful in isolation of biological material as defined in one of Claims 1 to 12, said process comprising: a) contacting a core comprising polyacrylonitrile or a copolymer of acrylonitrile and at least one comonomer with an alkaline catalyst, a liquid non-solvent for the core polymer having the ability to dissolve the alkaline reagent and peroxide while having only a limited ability to solvate the amide groups as they are formed, and a peroxide and, optionally, a reducing agent under reaction conditions and for a time sufficient to convert at least 2.5% of the nitrile groups distributed on the surface of the core to amide groups; b) reacting said amide groups with a halogenating reagent under conditions and for a time sufficient to convert 25 to 100% of the amide groups to N-haloamide groups; c) optionally reacting said N-haloamide group on said core with a bioactive ligand under conditions and for a time sufficient to effect the bonding of said ligand to said core; and d) recovering the surface-modified acrylonitrile polymer substrate. The process of Claim 13 wherein said peroxide comprises hydrogen peroxide and said reducing reagent is dimethyl sulfoxide. The process of Claim 13 wherein said halogenating agent is selected from the group consisting of chlorine, t-butyl hypochlorite, chloromonoxide, sodium hypochlorite, hypochlorous acid, sodium hypobromite and mixtures thereof. Method of use of the substrates according to one of Claims 1 to 12 having pendant bioactive ligand groups for the recovery and/or isolation of biological material from solution comprising contacting said solution with said substrate under conditions for a time sufficient to effect the bonding of said substrate and said biological material and recovering said substrate from said solution. The method of Claim 16 wherein said biological material comprises peptides, proteins, hormones, enzymes, antigens, antibodies, nucleic acids, polysaccharides, toxins, antitoxins or polynucleotides. The method of Claim 16 further comprising isolating said biological material from said substrate.

Inventors: ANDERSON LARRY STANLEY, LEY DAVID ARTHUR, WU-KWANG CHANG LAURENCE, ANDERSON, LARRY STANLEY, LEY, DAVID ARTHUR, WU-KWANG CHANG, LAURENCE
Applicants: CYTEC TECH CORP, CYTEC TECHNOLOGY CORP.
Application year: 1990
Main classification: C08F8
IPC codes: C08F20, B01D15, G01N30, G01N33, C12N11, B01J20, C08F8, C08J7, C08L33