Immobilized lipase post-encapsulated in Cu-based MOFs with promoted stability in biodiesel synthesis

Biodiesel is more environmentally friendly compared to traditional petroleum diesel. The method of producing biodiesel catalyzed by lipases, as a green chemistry technology, can further reduce its negative impact on the environment. In this work, lipase immobilized on magnetic cellulose was embedded in Cu(PABA), and then the biocomposite (MCL@Cu(PABA)) was used for biodiesel production. The good biocompatibility and flexible skeleton structure of cellulose can buffer the compression effect on enzyme molecules during the formation of Metal-Organic Frameworks (MOFs), and the MOFs protective layer can reduce the damage caused by denaturants to enzyme molecules. The biocatalyst showed enhanced activity and stability with a lower deactivation constant (K_d). Under the optimized reaction conditions, the biodiesel yield can reach 78.4 %. After reused for 7 times, the biocatalyst can still achieve a biodiesel yield of 58.8 %. Moreover, after stored for 30 days, the biodiesel yield can still reach 70.3 %. For all experimental yields, the standard deviation (SD) ranged from 2.4 % to 4.5 %. Secondary structure analysis showed that the rigid structure and active conformation of lipase was enhanced after Cu(PABA) encapsulation.