pH- and voltage-responsive chitosan hydrogel through covalent cross-linking with catechol.

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TitlepH- and voltage-responsive chitosan hydrogel through covalent cross-linking with catechol.
Publication TypeJournal Article
Year of Publication2012
AuthorsZhang, Y, Thomas, Y, Kim, E, Payne, GF
JournalJ Phys Chem B
Volume116
Issue5
Pagination1579-85
Date Published2012 Feb 9
ISSN1520-5207
KeywordsCatechols, Chitosan, Cross-Linking Reagents, Dielectric Spectroscopy, Electroplating, Hydrogel, Hydrogen-Ion Concentration, Oxidation-Reduction
Abstract

A new method for covalently cross-linking chitosan is developed by chemically oxidizing catechol to o-quinone which subsequently reacts with and cross-links chitosan through Michael addition and Schiff base formation. The cross-linked chitosan film shows a pH-responsive, switchlike behavior toward the negatively charged redox probe, Fe(CN)(6)(3-/4-), and withstands harsh acidic conditions. The negative Fe(CN)(6)(3-/4-) is found to be trapped and enriched in the catechol-cross-linked chitosan film under acidic conditions and released into solution by either increasing pH or applying a negative voltage. Chitosan films made with different techniques, i.e., solvent evaporation (simple deposition), electrodeposition, and covalent cross-linking, are examined using cyclic voltammetry and electrochemical impedance spectroscopy (EIS), and the results demonstrate that fabrication methods greatly affect the properties of the chitosan films.

DOI10.1021/jp210043w
Alternate JournalJ Phys Chem B
PubMed ID22229705