Immobilization of penicillin G acylase on a novel paramagnetic composite carrier with epoxy groups

In this work, Fe3O4 particles were first prepared by a reversed microemulsion method, and then the prepared nanoparticles were modified with 3-(trimethoxysilyl) propyl methacrylate (KH-570), a silane coupling agent, to enhance the dispersibility and biocompatibility of Fe3O4 particles. To get the graft ratio quantitatively, and further achieve the maximum loading capacity of KH-570, the characterization method for the graft ratio (Gr) was systemically explored first; reformative silicon molybdenum chromogenic (RSMC) was designed and presented a good result. In addition, the influence of operation conditions on the graft ratio was investigated and optimized. Results showed the graft ratio of KH-570 on magnetic Fe3O4 nanoparticles arrived at 178.51% under optimal conditions. In addition, it displayed KH-570 grafted onto the surface of Fe3O4 nanoparticles successfully, and only one silicon hydroxyl was bonded on the surface of Fe3O4 nanoparticles under optimal modifications. Finally, a magnetic composite carrier was prepared by grafting glycidyl methacrylate (GMA) onto the surface of the modified nanoparticles. Further, the composite was used to immobilize penicillin G acylase (PGA); in addition, the effect of GMA dosage on enzyme activity (EA), enzyme activity recovery rate (EAR), and enzyme loading rate (ELR) was studied. It was found that when the amount of GMA was 9.0%, the EA, EAR, and ELR were 9208 U/g, 88 mg/g, and 64.08%, respectively. In addition, the immobilized PGA still possess superparamagnetism, which can be well recycled and reused.