Abstract
Natural enzymes can efficiently and selectively catalyze various chemical reactions, but are limited by inherent fragility. Assembled via tailored metal nodes and organic ligands, metal-organic frameworks (MOFs) offer unique advantages for enzyme immobilization due to their customizable structures. According to the enzymes spatial position within MOF's structure, MOF-based enzyme immobilization strategies can be generally categorized into surface attachment, pore infiltration, and encapsulation. When enzymes are positioned close to MOF's surface, MOFs can offer limited protection. While deeper embedding provides stronger protection, it hinders the diffusion of substrates, products, and cofactors, thereby limiting catalytic efficiency. With advanced understanding of MOF synthesis, precise design and modulation of MOF structures enable improved performance of MOF-enzyme hybrids. According to MOF's diversity, precise design strategies of MOFs can be classified as surface microenvironment modulation, pore size and volume design, morphology tuning, and defect engineering. These strategies significantly optimize the enzymatic microenvironment, enzyme loading efficacy, and mass transfer, thereby improving the performance of MOF-enzyme hybrids. This review summarizes MOF-based enzyme immobilization strategies, explores precise designs overcoming various limitations, and highlights their applications in biosensing, biocatalysis, stimulus-responsive delivery, and cancer therapy. Additionally, the potentials of MOFs with enhanced enzyme stability and functionality in broader applications are explored.