Study on the modification of magnetic graphene oxide and the effect of immobilized lipase.

In this study, magnetic nanoparticles (MNPs) were combined with graphene oxide (GO) to effectively improve the immobilization effect of lipase, and magnetic graphene oxide (MGON) was modified to immobilize Candida rugosa lipase (CRL) with functionalized MGON as a carrier. The optimal magnetic carrier was screened. Characterization and analysis revealed that the specific surface area of MGON was 263.75 m·g. The magnetic saturation intensities of the carrier modified with γ-ureapropyltrimethoxysilane (TMSPU), γ-aminopropyltriethoxysilane (APTES), and γ-mercaptopropyltriethoxysilane (MPTS) were 26.67, 35.1, and 43.1 emu/g, respectively. The enzyme carrying amounts of the three immobilized enzymes were 402.6, 323.4, and 288.8 mg/g, respectively. The number of binding sites of the modified carrier of TMSPU was more than that of the two other modified carriers. The optimum temperature of magnetic immobilized enzyme was 50 °C, its optimum pH was 7.0, and it had good thermal stability. The immobilized enzyme modified with TMSPU retainsed 80.28 % of the relative enzyme activity after eight times of reusability. These results demonstrated that TMSPU-modified MGON showed potential for applications involving enzyme immobilization.