Preparation and Catalytic Properties of Lipase Immobilized on Epoxy-functionalized Starch Nanoparticles

Graphical The contact angle of modified starch was changed from 12.2° to 71.5°, and the particle size was changed from ∼10 μm to ∼300 nm. In the subsequent enzyme catalyzed reaction, the immobilized enzyme is adsorbed at the water oil interface, thereby improving the lipase activity. As a natural macromolecular material, starch is an ideal carrier for enzyme immobilization because of its widely available source, easy regeneration and excellent biodegradability. However, the natural starch cannot be directly used for immobilization due to the large particle size and excessive hydrophilicity. In this paper, the epoxy groups were grafted onto esterified starch by bifunctional reagents. The grafting efficiency of epoxy groups was increased by starvation drop addition. The changes of contact angle and particle size are conducive to the adsorption of immobilized enzyme at the water oil interface in the subsequent enzyme catalytic reaction, hence improve of the lipase activity. The maximum amount of lipase mobilized on such modified starch was ∼143.7 mg/g, which was near 40 mg/g higher than that of those from direct crosslinking. The immobilized enzymes showed excellent resistance to organic solvents and good reusability. Immobilization of lipases on epoxy-functionalized starch nanoparticles can potentially improves the possibility of enzymes industrial application.