Magnetic-Responsive Starch-Based Particles as an Interfacial Stabilizer and Enzyme Carrier for Sustainable Pickering Interfacial Catalysis

Stimulus-responsive Pickering interfacial catalysis (PIC) system is an efficient platform for enzyme-catalyzed reactions. As a natural and biodegradable polymer, starch has great advantages as an interfacial stabilizer. However, the design of a mild magnetic response to achieve the separation of oil and aqueous phases and reusability of the enzyme in the starch-based PIC has rarely been reported. Herein, we reported a functionalized quinoa starch particle (CRL@DA-MQS) through Fe3O4 grafting, dopamine coating, and lipase immobilization and then applied it as both an emulsifier and a catalyst to fabricate a magnetic-responsive PIC system. It showed a high conversion rate of 87.67% in the esterification reaction of phytosterol and linoleic acid. The specific enzyme activity of the PIC system (4.58 U/mg) was approximately 1.6 times higher than that of free lipase of a Pickering assistant catalysis system with native quinoa starch particles as emulsifiers. The PIC system was broadly applicable for several fatty acids as substrates, with all conversion rates above 70%. It also demonstrated excellent reusability, maintaining a relative conversion rate of over 90% even after ten cycles. These results provided valuable insights into a magnetic starch-based biocarrier for enzyme immobilization and the application of this lipase-adsorbed particle as a green and recyclable biocatalyst in the PIC system.