Efficient immobilization of lipase from Candida rugosa by entrapment into poly(N-isopropylacrylamide-co-itaconic acid) hydrogels under mild conditions

Abstract

Temperature and pH-sensitive hydrogels, based on N-isopropylacrylamide and itaconic acid, with varying comonomer ratios and crosslinking agent content, were prepared by free radical crosslinking copolymerization. The immobilization of lipase from Candida rugosa was carried out by post-loading entrapment method at different temperatures until equilibrium swelling was achieved. The effects of the hydrogel composition and the immobilization temperature on the hydrogel-binding capacity, immobilized lipase specific activity, as well as the enzyme leakage were studied. It was found that the NiPAAm/IA ratio, crosslinking agent concentration and the temperature at which the entrapment was performed significantly affected the hydrogel-binding capacity. The biocatalysts obtained by entrapment into hydrogel with the highest itaconic acid content at 5 °C exhibited both highest binding capacity and the highest specific activity, but appeared to be less suitable for repeated uses than those obtained at 25 °C.