Development of Cellulose Hydrogel Microspheres for Lipase Immobilization

Abstract

Cellulose hydrogel microspheres were prepared by sol-gel transition using an ionic liquid-in-oil emulsion. Factors that influenced the formation of these microspheres, including the ratio of ionic liquid to oil, surfactant concentration, and stirring speed, were optimized for lipase immobilization. Using the optimized method, Candida rugosa lipase was efficiently immobilized on the microspheres by physical adsorption. As compared with the free lipase, the specific activity of the immobilized lipase was 1.4 times higher, its half-life at 45°C was 41 times longer, and it showed an enhanced stability over a wide pH range. The lipase immobilized on cellulose microspheres showed a much higher loading efficiency, immobilization yield, and specificity constant than lipase immobilized on microcrystalline cellulose or millimeter-sized hydrogel beads. To increase the reusability of cellulose microspheres as an enzyme support material, magnetic cellulose microspheres were also prepared by adding Fe3O4. The lipase immobilized on magnetic cellulose microspheres was simply recovered using a magnet and continuously reused with a minimal loss of activity.