Nanostructured Biocatalysts

Abstract

Enzymes can be encapsulated in nanogels of tunable size ranging from 10 to 50 nm by using an aqueous two-step in situ polymerization method. In the first step, vinyl groups are generated on the enzyme surface by acryloylation, and this is followed by aqueous in situ polymerization that encapsulates the acryloylated enzyme into the nanogel. The biocatalytic behavior of the enzyme nanogel is similar to that of the native enzyme, as evidenced by the K m and k cat values, but the enzyme nanogel shows significantly enhanced stability at a high temperature and in the presence of a polar organic solvent. The strengthened integrity by multipoint linkage with the thin and porous polymer network and the exclusion of polar solvent from enzyme surface, as also illustrated by molecular dynamics simulation, contributes to the enhanced stability of the encapsulated enzyme in these adverse conditions. The potential of the enzyme nanogel as robust catalysts has been tested by using lipase nanogel for (1) production of biodiesel by methanolysis of soybean in oil–water biphasic media at 55 ˚C; (2) synthesis of hydrophobic-modified dextran as a biodegradable surfactant in anhydrous dimethyl sulfoxide at 65 ˚C; and (3) polycondensation of succinic acid and 1,4-butanediol at 95 ˚C under high vacuum.