Aldehydepropyl-functionalized mesostructured cellular foams: Efficient supports for immobilization of penicillin G acylase

Abstract

Abstract The aldehydepropyl-functionalized mesostructured cellular foams (CHO-MCFs) were prepared by post-synthetical functionalization of MCFs with trimethoxysilylpropanal (TMSP), and used as efficient supports for immobilization of penicillin G acylase (PGA). The physicochemical properties of CHO-MCFs were characterized by SAXS, nitrogen sorption, TEM, elementary analysis, solid state 29 Si MAS NMR, FT-IR spectroscopy and thermogravimetry. The results show that the aldehydepropyl groups have been grafted successfully on the surface of MCFs, and after functionalization, the BET surface area and pore volume of CHO-MCFs decrease, but the ultra-large and continuous 3D mesoporous structure of CHO-MCFs are retained to be beneficial for immobilization of PGA with large size and diffusion of substrates and products. PGA is immobilized covalently on CHO-MCFs via the reaction to produce Schiff's base between the free amino groups of lysine residues of PGA and the aldehyde groups on the surface of CHO-MCFs, which greatly increases the operational stability of the immobilized PGA with little activity loss due to the short-chain groups of aldehydepropyl grafted on the surface of CHO-MCFs. PGA/CHO-MCFs-10 shows the immobilization yield of 57.6%, the specific activity of 22.2 U/mg and the initial enzymatic activity of 8895 U/g, and retains 93.0% of its initial enzymatic activity after recycled for 10 times.