pH- and voltage-responsive chitosan hydrogel through covalent cross-linking with catechol.
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.
Department of Chemistry, Morgan State University, Baltimore, Maryland 21251, USA. yongchao.zhang@morgan.edu
Yongchao
Y
Zhang
Yanique
Y
Thomas
Eunkyoung
E
Kim
Gregory F
GF
Payne
D002396:Catechols / Q000737:chemistry*; D048271:Chitosan / Q000737:chemistry*; D003432:Cross-Linking Reagents / Q000737:chemistry*; D058266:Dielectric Spectroscopy; D004595:Electroplating; D020136:Hydrogel, Polyethylene Glycol Dimethacrylate / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D010084:Oxidation-Reduction
D002396:Catechols; D003432:Cross-Linking Reagents; D020136:Hydrogel, Polyethylene Glycol Dimethacrylate; D048271:Chitosan; C034221:catechol