title: Boronate-containing copolymers: polyelectrolyte properties and sugar-specific interaction with agarose gel.
abstract: Copolymers of N-acryloyl-m-aminophenylboronic acid (NAAPBA) with acryamide (AA), N,N-dimethylacrylamide (DMAA), and N-isopropylacrylamide (NIPAM) were found to adsorb on cross-linked agarose gel (Sepharose CL-6B) in the pH range from 7.5-9.2, due to specific boronate-sugar interactions. The molar percentages of phenylboronic acid (PBA) groups in the boronate-containing copolymers (BCCs), as estimated by 1H NMR spectroscopy, were 13, 10, and 16%, respectively, whereas the apparent ionization constants, the pKa values, of the copolymers were similar and equal to 9.0 +/- 0.2 at 20 degrees C. The copolymers adsorption capacities were in the range of 15-30 mg x ml(-1) gel (14-36 micromol pendant PBA ml(-1) gel) at pH 9.2 and decreased with decreasing pH value. The interaction of monomeric NAAPBA with Sepharose CL-6B was characterized by an equilibrium association constant of 53 +/- 17 M(-1), the chromatographic capacity factor k' = 1.8, and a total content of binding sites of 27 +/- 10 micromol x ml(-1) gel at pH 9.2. The weak reversible binding of monomeric NAAPBA and almost irreversible binding of NAAPBA copolymers to the gel at pH 9.2 suggested a multivalent character of the copolymer adsorption. At pH 7.5, the maximal adsorption capacity was displayed by the AA-NAAPBA copolymer (15 mg x ml(-1) gel). All the BCCs could be completely desorbed from the gel by 0.1 M fructose in aqueous buffered media with pH values from 7.5-9.2. The strong adsorption of AA-NAAPBA on agarose gel probably relates to the conformation of the copolymer in aqueous solution and provides opportunities for biomedical applications of the copolymer under physiological conditions. Multivalent, weak-affinity adsorption of BCCs to the agarose gel seems to be a tentative model for the copolymers' binding to oligo- and polysaccharides of cell membranes and mucosal surfaces.
authors.affiliation: Department of Biotechnology, Center for Chemistry and Chemical Engineering, Lund University, P.O. Box 124, SE-22100, Lund, Sweden.
authors.forename: Marina V
authors.initials: MV
authors.lastname: Kuzimenkova
authors.forename: Alexander E
authors.initials: AE
authors.lastname: Ivanov
authors.forename: Igor Yu
authors.initials: IY
authors.lastname: Galaev
mesh_terms: D000327:Adsorption; D001672:Biocompatible Materials / Q000138:chemical synthesis / Q000737:chemistry; D001897:Boronic Acids / Q000737:chemistry; D002241:Carbohydrates / Q000737:chemistry; D002846:Chromatography, Affinity; D004573:Electrolytes / Q000737:chemistry; D005782:Gels; D006863:Hydrogen-Ion Concentration; D008024:Ligands; D009682:Magnetic Resonance Spectroscopy; D008970:Molecular Weight; D011108:Polymers / Q000138:chemical synthesis / Q000737:chemistry*; D012685:Sepharose; D013499:Surface Properties
chemical_list: D001672:Biocompatible Materials; D001897:Boronic Acids; D002241:Carbohydrates; D004573:Electrolytes; D005782:Gels; D008024:Ligands; D011108:Polymers; D012685:Sepharose