Composite beads of silica gel, alginate and poly(aspartic acid) for the immobilization of a lipase enzyme

Abstract

Silica gel/alginate/poly(aspartic acid) composite beads were prepared for immobilization of lipase B enzyme from Candida antarctica (CaLB). CaLB was first adsorbed on functionalized mesoporous silica gel particles, which were then entrapped in the interpenetrating network of thiolated poly(aspartic acid) and alginate, cross-linked by zinc ions. Finally, the beads were chemically stabilized by poly(ethylene glycol) diglycidyl ether, a bisepoxide cross-linker. In this manner, spherical biocatalysts with a diameter of 3–4 mm were prepared and their biocatalytic performance was tested by kinetic resolution of racemic 1-phenylethanol. The activity of CaLB in the beads was comparable to that of CaLB physically adsorbed on silica gel particles. The composite beads were easy to recover after use and no loss of biocatalytic activity was observed even after five test reaction cycles. Furthermore, the CaLB in the composite beads showed sufficient thermal stability up to 90 °C, contrary to CaLB adsorbed only on silica gel particles.

Keywords

• Polymer composites
• Biodegradable polymers
• Biocatalysis
• Enzyme
• Kinetic resolution