Preparation and properties of enzyme-carrying silica xerogel based on TMOS/MTMS co-precursors

In the entrapment of enzymes by sol-gel method, the special procedures for obtaining the unique structure of xerogel are sometimes destructive to enzymes, while the internal structure of xerogels is easily broken. To solve the above problems, we present an economical, bio-friendly procedure for the entrapment of Candida antarctica lipase B in silica xerogel. In this procedure, an encapsulation-structured enzyme-carrying silica xerogel was produced by controlling the evaporation rate of the solvent at ambient pressure during drying, while tetramethoxysilane and methyltrimethoxysilane were used as the co-precursors. The xerogel synthesis was modified and optimized for improving the stability and reusability of the enzyme, while the xerogel characteristic structure was preserved. Moreover, the effects of the co-precursors amount on the mechanical strength, pore structure, hydrophobicity, enzyme loading, and enzyme stability of the enzyme-carrying silica xerogels were systematically investigated. And the best performance was observed at the co-precursors content of 30.28 wt%. Finally, the catalytic performance of the enzyme-carrying silica xerogels on the transesterification of n -butanol with ethyl acetate was demonstrated. Graphical abstract