Immobilization of Candida Antarctica lipase B on epoxy modified silica by sol-gel process

Abstract

An epoxy-functionalized silica support was prepared through 3-glycidoxypropyltrimethoxylsilane(KH560)modified silica sol in the presence of triblock copolymer F127 (F-560-S). The surface chemistry, micromorphology and pore structure of the supports were characterized by TG, FTIR, SEM and N2 adsorption-desorption, which showed that the BET surface areas and pore volumes of epoxy-activated supports increased with the addition of F127. The Candida Antarctica Lipase B (CALB) was immobilized on the resulting carrier by covalent link. The lipase absorbed amounts were 58mg/g support and 375mg/g support on the normal silica (N-S) and modified silica (F-560-S), respectively. The immobilized lipases were examined as biocatalysts for transesterification of 1-phenethanol and vinyl acetate in nonaqueous medium. Solvents and temperature were investigated for influence of morphology and KH560 on the immobilized lipase. The catalytic activity of the CALB immobilized on F-560-S was improved in various solvents, especially in polar solvents. The immobilized CALBs maintained high activity, while the control experiment using free lipase gave very low ester production in the temperature range of 0–60°C. Furthermore improved thermal stability of CALB immobilized on F-560-S compared to the CALB on N-S was observed. The CALB immobilized on F-560-S exhibited high operational stability in organic media which still retained 88.3% of its original activity for 12h consecutive 7 runs.