W. Kamimura et al., Self-complex formation of nicotinamide-modified dextran with carboxymethyldextran using their degradation products, J BIOM SC P, 11(7), 2000, pp. 747-765
A pseudo-metabolic cycle as a self-degradation system was designed: enzymat
ic degradation products from a polysaccharide generate oxidants which intro
duce a cationic charge into the polysaccharide chains, and can form a polyi
on complex with an anionic polysaccharide. As a component of such a system,
dextran, with various degrees of nicotinamide substitution, was prepared.
Its degradation by dextranase, redox reaction via glucose oxidase-catalysis
, and polyion complex formation with carboxymetyl dextran (CMD) were examin
ed. Nicotinamide-modified dextran (NA-Dex) with nine nicotinamide moieties
per 100 glucose units was soluble in PBS and completely oxidized by >100 mM
H2O2 The oxidized type of NA-Dex was found to form a 1 : 1 complex with CM
D. By the addition of dextranase, isomaltase, and glucose oxidase (GOD) to
phosphate buffer solution of the reduced type of NA-Dex and CMD, the transm
ittance of the solution dropped, suggesting polyion complex formation via t
he oxidation of 1,4-dihydronicotinamide in NA-Dex by H2O2 generated from GO
D-catalytic reaction. These findings are of great importance for designing
a self-complex formation system aimed at biodegradable and osillative drug
release.