Immobilization of lipase in chitosan-mesoporous silica material and pore size adjustment.

Mesoporous silica MCM-41 was modified by carboxyl groups and assembled with chitosan to produce a novel nanocarrier for the immobilization of lipase. The prepared composite was grafted with silane coupling agent KH560 to decrease the pore size of the mesoporous material and prevent the loss of shed lipase molecules. According to the characterization of the material before and after modification and determination of related parameters, the residual activity of the lipase fixed in the CTS-MCM-41 carrier was 85 % after seven repeated use cycles. The grafting rate of MCM-41 and shrinkage effect were maximized when the concentration of KH560 was 5.0 %, and the modification was performed at 4 h at 70 °C. Using glutaraldehyde as the crosslinking agent, the optimal conditions for enzyme immobilization involved a mass ratio of the carrier to enzyme of 4:1, glutaraldehyde solution volume of 3 %, reaction time of 3 h, and reaction temperature of 45 °C. Overall, the proposed innovative carrier for the fixation of lipase is stable and can physically control the free enzyme in the pore. Moreover, the efficient miniature lipase reactor can promote large-scale industrial production.