Facile Preparation of Dopamine-Modified Magnetic Zinc Ferrite Immobilized Lipase for Highly Efficient Synthesis of OPO Functional Lipid

Abstract

1,3-Dioleoyl-2-palmitoylglycerol (OPO) has been a hotspot of functional oils research in recent years, but due to the high cost of sn-1,3 specific lipase in enzymatic synthesis and the lack of biocatalyst stability, large-scale industrial application is difficult. In this study, the prepared magnetic ZnFe2O4 was functionalized with dopamine to obtain ZnFe2O4@PDA, and the nano-biocatalyst ZnFe2O4@PDA@RML was prepared by immobilizing sn-1,3 specific lipase of Rhizomucor miehei lipase (RML) via a cross-linking method. The existence of RML on ZnFe2O4@PDA was confirmed by XRD, FTIR, SEM, and TEM. This strategy proved to be simple and effective because the lipase immobilized on magnetic nanoparticles could be quickly recovered using external magnets, enabling reuse of the lipase. The activity, adaptability to a high temperature, pH value, and operational stability of immobilized RML were superior to those of free RML. After optimizing the synthesis conditions, the OPO yield was 42.78%, and the proportion of PA at the sn-2 position (PA-Sn2) was 54.63%. After the first four cycles, the activity of ZnFe2O4@PDA@RML was not significantly affected. The magnetically immobilized lipase has good thermal stability, long-term storage stability, reusability, and high catalytic activity. It can be used as a green and efficient biocatalyst to synthesize the OPO functional lipid.