Immobilization of lipase on metal-organic frameworks and investigation of their catalytic properties and stability.

Surface adsorption is a convenient and readily available method for immobilizing enzymes on metal-organic frameworks (MOFs). Metal-organic framework-5 (MOF-5), isoreticular metal-organic frameworks-3 (IRMOF-3), and multivariate analysis of MOF-5/IRMOF-3 (MMI) with a half-amino group (-NH) were prepared in this study. lipase (TLL) was chosen as a commercially available enzyme for immobilization on the surfaces of these MOFs. Briefly, 1.5 mg of TLL was added to 10 mg of the MOFs, and after 24 h, 67, 74, and 88% of the TLL was immobilized on MOF-5, IRMOF-3, and MMI, respectively. Fourier transform infrared spectroscopy, X-ray diffraction, thermogravimetric analysis, scanning electron microscopy, energy-dispersive X-ray analysis, and Brunauer-Emmett-Teller analysis were used to characterize the resulting biocomposites. TLL@MOF-5, TLL@IRMOF-3, and TLL@MMI exhibited activities of 55, 75, and 110 U/mg, respectively. Investigation of the activity and stability of the prepared biocatalysts showed that TLL immobilized on MMI was 2.34-fold more active than free TLL. TLL@MMI exhibited high stability and activity even under harsh conditions. After 24 h of incubation in a mixture of 50% (v/v) MeOH, TLL@MMI retained 80% of its activity, whereas TLL@MOF-5 and free TLL lost 50 and 60% of their activities, respectively. TLL@MMI was used to synthesize 2-arylidenehydrazinyl-4-arylthiozole derivatives (91-98%) in a one-pot vessel by adding benzaldehydes, phenacyl bromides, and thiosemicarbazide to water. The efficiency of the 4a derivative with free TLL was 43%, whereas that with TLL@MMI was 98%.