Amino Acid Ionic Liquid Activation of Biomimetic Magnetic Graphene for Enhancing Lipase Stability and Catalytic...

The limited stability and insufficient recyclability of lipase (CRL), a crucial biocatalyst, hinder its extensive industrial application. In this study, we successfully immobilized CRL on a magnetic graphene surface by using polyethyleneimine and polydopamine (PEI/PDA) bionic adhesive as a flexible connecting branch and amino acid ionic liquid as an activator. The immobilized enzyme exhibited markedly enhanced thermal stability and denaturant tolerance. Specifically, the immobilized enzyme retained more than 80% activity after incubation at 60 °C for 1 h, which was approximately 1.8 times higher than that of the free enzyme. Additionally, following incubation in 6 mol/L denaturant for 2 h, the immobilized enzyme maintained over 80% activity. Moreover, the immobilized enzyme displayed superior storage stability and magnetic properties, significantly simplifying the recovery process. Notably, even after seven reuses, the immobilized enzyme retained more than 70% of its catalytic activity. When the immobilized enzyme was applied to the synthesis of phytosterol esters, an esterification rate of 90.2% was achieved. Moreover, the enzyme maintained a high activity level, with the esterification rate still exceeding 70% after five cycles of reuse, demonstrating excellent reusability. This research would not only offer innovative strategies for lipase immobilization but also establish a robust theoretical framework for the application of ionic liquids in immobilized enzyme technology, thereby providing important support for the industrial application of biocatalysts.