PVP-assisted in situ immobilizing lipase on covalent organic framework for enhanced catalytic activity and stability in bioconversions

Covalent organic frameworks (COFs) are crystalline, porous organic materials that have significant potential as supports for enzyme immobilization. Nevertheless, the in situ preparation of biocatalysts during the COF formation process remains a considerable challenge. Herein, we developed a one-pot in situ preparation strategy. The immobilized lipase PS@TPB-TFPB COF-I was fabricated by mixing the polyvinylpyrrolidone (PVP)-lipase PS complex with precursors 1,3,5-tris(4-aminophenyl)benzene (TPB) and 1,3,5-tris(4-formylphenyl)benzene (TFPB) in acetonitrile catalyzed by acetic acid at room temperature for 48 h. The formation mechanism was systematically investigated using time-dependent microscopy techniques. PVP acts as a guiding reagent, controlling the morphological changes that occur during this process. Furthermore, the biocatalyst was employed in the kinetic resolution of racemic 1-phenylethanol, resulting in a significant enhancement in the conversion rate, with a range of 2.1 to 10.6 times higher compared to free PS at the same reaction time. The robust biocatalyst maintained high catalytic activity and enantioselectivity even after 10 cycles. The strategy described here is promising for lipase immobilization and expands the range of applications for COFs in biomanufacturing.