Preparation of light core/shell magnetic composite microspheres and their application for lipase immobilization

Abstract

Fe₃O₄@P(GMA-DVB-MAA) magnetic composite microspheres were prepared by facile one-pot distillation–precipitation polymerization. The composite microspheres were formed using a P(GMA-DVB-MAA) copolymer as the shell and hollow magnetic Fe₃O₄ nanoparticles as the core. During the distillation–precipitation polymerization, non-modified Fe₃O₄ nanoparticles can be encapsulated and the thickness of the polymer shell layer can be adjusted by the amount of monomer used. The as-prepared particles showed excellent magnetic responsibility, well-defined core/shell structure and monodispersity. Lipase is one of the best biocatalysts which can catalyze a variety of reactions, such as alcoholysis, hydrolysis, aminolysis, esterification and transesterification. Fe₃O₄@P(GMA-DVB-MAA)–NH₂ composite microspheres were obtained by modification of hexamethylenediamine and they were used for Candida rugosa lipase (CRL) immobilization. The immobilization conditions were systematically studied and the hydrolysis of olive oil emulsion was used for the examination of lipase activity. The characterization of the immobilized lipase indicated that the immobilization amount was up to 131.9 mg g⁻¹ and that the relative activity remained at 65% after ten cycles. The immobilized lipase still held 41% relative activity after 140 h at 50 °C. All these results show that the immobilized lipase exhibited excellent thermal stability and reusability. This kind of immobilized lipase has great potential in industrial application because it is easy to separate from the system.