A mixed-function-grafted magnetic mesoporous hollow silica microsphere immobilized lipase strategy for ultrafast transesterification in a solvent-free system

Abstract

Although enzymatic catalysis is an attractive approach for the green synthesis of chemicals, it often suffers from low reactivity and poor stability during the reaction. In this study, lipase from Candida rugosa (CRL) was immobilized and stabilized on magnetically-separable, mixed-function-grafted, large pore mesostructured magnetic hollow mesoporous silica microspheres (MHMSS) by means of multiple-mode adsorption based on both hydrophobic and strong cation-exchange interactions. Benefiting from the hollow large mesoporous structure, ultrafast enzyme immobilization could be realized in 5 min, with a high loading of CRL (95.2 mg g⁻¹). Stabilized CRL@MHMSS was successfully used for the ultrafast transesterification of phytosterol with fatty acids and triglycerides in a solvent-free system, which reached high conversions (≧90.9%) within 15 min at 55 °C. Magnetic separation of MHMSS facilitated the repeated usage of CRL@MHMSS for more than 50 successive reactions without damaging its catalytic activity. Its high activity and stability make the MHMSS immobilized enzyme an attractive catalyst for green synthesis in a solvent-free system.