alpha-chymotrypsin as model enzyme was anchored to the carboxyl-functionalized magnetic nanogels prepared by in situ photochemical polymerization. Furthermore, to explore the optimum in mobilization, the effects of immobilization time, pH of the reaction mixture, and proportion of enzyme to the magnetic nanogels were studied. The immobilized enzyme vas stable in the presence of enzyme denaturation surfactants, and maintained their activity against protein-digesting enzyme. The immobilized enzyme exhibited hydrolysis activity against the substrate of casein, and cleaved the Substrate into small fragments. (C) 2008 Wiley Periodicals, Inc. J Appl Polym Sci 111: 2844-2850, 2009