Immobilization of Lipase from Thermomyces lanuginosus in Magnetic Macroporous ZIF-8 Improves Lipase Reusability in Biodiesel Preparation

In recent years, metal–organic frameworks (MOFs) have emerged as a promising support for immobilizing enzymes due to their high designability and structural diversity. Previous studies show that MOFs with single-crystal-ordered macroporous structures can effectively improve the accessibility of large-size enzyme and reduce the mass transfer resistance compared to conventional MOFs. In order to further enhance the reusability of lipase immobilized on macroporous MOFs, modification of MOFs through some magnetic particles could be an efficient approach. In this work, magnetic macroporous zeolitic imidazolate framework-8 (ZIF-8), referred to as m-M-ZIF-8 (with an average macropore size of about 140 nm), was synthesized and used for the immobilization of Thermomyces lanuginosus lipase (TLL). It was found that enzyme loading and the specific enzyme activity of the immobilized lipase were greatly enhanced through this magnetic modification. The enzyme loading of TLL@C-ZIF-8, T LL@M-ZIF-8, and TLL@m-M-ZIF-8 was 0.060, 0.074, and 0.076 mg/mg respectively. Besides, the activity of 93.5% was maintained after the immobilized lipase being repeatedly used for five batches, which was much higher than that of the immobilized lipase without magnetic modification, which was only 73.4%.