title: Transience in polyion complexation between nicotinamide-modified dextran and carboxymethyl dextran during enzymatic degradation of dextran.
abstract: A self-regulated degradation system using polyion complexation through oxidation reaction from degradation products was preliminarily studied. 1,4-Dihydronicotinamide-modified dextran (NAH-Dex) with different molecular weights was prepared, and NAH moiety in NAH-Dex was oxidized by H2O2 to the dehydrated form (NA+-Dex). The dependence of stoichiometry, concentration, and molecular weight on polyion complexation with carboxymethyl dextran (CMD) were examined. NA+-Dex with a molecular weight above 40000 formed an insoluble complex with CMD, and the complexation was found to proceed stoichiometrically. The extent of polyion complexation was dependent on the concentration of NA+-Dex and CMD, whereas the time to reach complexation was dependent on H2O2 concentration. When H2O2 and dextranase were added to the solution containing NAH-Dex, CMD, and dextran, transmittance dropped and then increased again. From these results, the addition of dextran into the system of H2O2, NAH-Dex, CMD, and dextranase can regulate formation and dissociation of the polyion complex between NA+-Dex and CMD. The antagonistical inhibition of the degradation of the polyion complex is a key parameter of the self-regulated degradation system.
authors.affiliation: School of Materials Science, Japan Advanced Institute of Science and Technology, Tatsunokuchi, Ishikawa.
authors.forename: W
authors.initials: W
authors.lastname: Kamimura
authors.forename: T
authors.initials: T
authors.lastname: Ooya
authors.forename: N
authors.initials: N
authors.lastname: Yui
mesh_terms: D001672:Biocompatible Materials / Q000737:chemistry / Q000378:metabolism; D001673:Biodegradation, Environmental; D003910:Dextranase / Q000378:metabolism; D003911:Dextrans / Q000737:chemistry / Q000378:metabolism; D005949:Glucose Oxidase / Q000378:metabolism; D006861:Hydrogen Peroxide; D008422:Materials Testing; D008970:Molecular Weight; D009536:Niacinamide; D009834:Oligo-1,6-Glucosidase / Q000378:metabolism; D010084:Oxidation-Reduction
chemical_list: D001672:Biocompatible Materials; D003911:Dextrans; D009536:Niacinamide; C014392:carboxymethyl dextran; D006861:Hydrogen Peroxide; D005949:Glucose Oxidase; D009834:Oligo-1,6-Glucosidase; D003910:Dextranase