pH-Dependent release of blue dextran from carboxymethyl-β-cyclodextrin hydrogels

초록

Carboxymethyl-beta-cyclodextrin (CM-beta-CD) hydrogel was prepared by cross-linking beta-CD and substituting the hydroxyl groups with carboxymethyl group. Epichlorohydrin (EPI) was used as a cross-linker and the molar ratio of EPI to beta-CD was 10:1. The number of carboxymethyl group per beta-CD residue was determined by a back-titration method and the value was 0.86. The swelling ratio of CM-beta-CD hydrogel increased as the pH of medium increased. The carboxyl group will be ionized with increasing pH and an electrostatic repulsion developed within the hydrogels would be responsible for a higher swelling ratio at a higher pH. The degree of release of blue dextran from the hydrogel also increased as the pH of medium increased. The pH-dependent swelling ratio could account for the pH-sensitive release. (C) 2010 Published by Elsevier B.V. on behalf of The Korean Society of Industrial and Engineering Chemistry.

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