Nanogel-dressed Candida rugosa lipase: Enhanced biocatalysis through hierarchically porous metal organic frameworks' integration

Abstract

Candida rugosa lipase (CRL) is a multifunctional biological macromolecule extensively employed in biocatalysis, but its stability and reusability remain significant challenges. This study investigates the immobilization of CRL nanogels onto hierarchically porous metal-organic frameworks (HP-MOFs), possessing adjustable porosity, high surface area, and stability, making them ideal for enzyme immobilization. CRL nanogels were synthesized and immobilized onto three different HP-MOFs: hZIF-8, HP-UiO-66-NH₂, and HP-CuBTC via adsorption. The HP-MOFs were synthesized using soft templating, post-synthetic ligand substitution, and rapid room-temperature templating, ensuring high porosity and structural integrity. The CRL nanogels, characterized by transmission electron microscopy (TEM), fluorescence spectroscopy, and fourier transform infrared spectroscopy (FTIR), were encapsulated in polyacrylamide nanogels, suggesting a hydrophobic environment within the matrix. Comprehensive characterization using scanning electron microscopy (SEM), TEM, thermogravimetric analysis (TGA), FTIR, X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET) surface area analysis, and X-ray photoelectron spectroscopy (XPS) confirmed successful immobilization while preserving structural integrity. Enzyme kinetics analysis revealed that the nanoCRL@HP-MOF composites exhibited significantly enhanced enzymatic activity, stability, and reusability compared to free CRL. To the best of our knowledge, this study represents the first demonstration of CRL nanogel immobilization on multiple HP-MOFs, providing valuable insights into their potential as enzyme carriers with promising applications in biotechnological processes.