Chitosan‐grafted poly(hydroxyethyl methacrylate‐co‐glycidyl methacrylate) membranes for reversible enzyme immobilization

Epoxy group‐containing poly(hydroxyethyl methacrylate/glycidyl methacrylate), p(HEMA/GMA), membrane was prepared by UV initiated photopolymerization. The membrane was grafted with chitosan (CH) and some of them were chelated with Fe(III) ions. The CH grafted, p(HEMA/GMA), and Fe(III) ions incorporated p(HEMA/GMA)‐CH‐Fe(III) membranes were used for glucose oxidase (GOD) immobilization via adsorption. The maximum enzyme immobilization capacity of the p(HEMA/GMA)‐CH and p(HEMA/GMA)‐CH‐Fe(III) membranes were 0.89 and 1.36 mg/mL, respectively. The optimal pH value for the immobilized GOD preparations is found to have shifted 0.5 units to more acidic pH 5.0. Optimum temperature for both immobilized preparations was 10°C higher than that of the free enzyme and was significantly broader at higher temperatures. The apparent K_m values were found to be 6.9 and 5.8 mM for the adsorbed GOD on p(HEMA/GMA)‐CH and p(HEMA/GMA)‐CH‐Fe(III) membranes, respectively. In addition, all the membranes surfaces were characterized by contact angle measurements. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 3084–3093, 2007