Ionic Liquid Modification Optimizes the Interface between Lipase and Magnetic GO for Enhancing Biocatalysis

In this study, imidazolium-based ionic liquids (ILs) were used to modify carboxymethyl cellulose-coated Fe3O4 nanoparticles with graphene oxide deposition (ILs-MCMC/GO). The prepared composites were characterized and used to immobilize lipase. The prepared biocatalyst (PPL-ILs-MCMC/GO) exhibited higher activity, which was 3.55-fold that of free lipase and 1.41-fold that of immobilized lipase without IL (PPL-MCMC/GO). After reusing 10 times, the residual activity of PPL-ILs-MCMC/GO was 91.3%, which was higher than those of PPL-MCMC/GO (83.6%) and PPL-MCMC (73.6%). In addition, using kinetic analysis, we showed that the affinity between PPL-ILs-MCMC/GO and the substrate was improved. The secondary structures of free and immobilized lipase were analyzed to explain the mechanism by which the performance of PPL-ILs-MCMC/GO was improved. The introduction of imidazole-based IL was useful in improving the microenvironment of immobilized lipase. Furthermore, magnetic supports loaded with lipase could be recovered easily.