Metal-organic frameworks (MOFs) for enhanced biological CO₂ fixation: Advances and applications in enzyme catalysis and living cell applications

The conversion of CO₂ into fuels and chemicals via biological routes has gained significant attention due to its high efficiency and mild reaction conditions. However, biological CO₂ fixation faces several challenges, including the low solubility of CO₂, the poor stability of free enzymes and cells under harsh conditions, and the high cost of cofactors such as NAD(P)H. Metal-organic frameworks (MOFs), with their unique characteristics including high surface area, tunable pore structure, and ease for functionalization, have emerged as promising candidates to address these limitations. When integrated into biological CO₂ fixation systems, MOFs serve multiple functions: as CO₂ capture agents, enzyme immobilization carriers, cellular protective layers, and scaffolds for photosensitizers and electron mediators for efficient cofactor regeneration. Despite extensive reviews on MOF-based chemical CO₂ conversion, their applications in biological CO₂ fixation have not been reviewed. This review first introduces the characteristics and synthesis methods of MOFs, followed by an in-depth exploration of MOFs applications in biological CO₂ fixation systems. For enzyme-based systems, this review explores strategies for enzyme immobilization and synergistic integration of other key catalytic components within MOFs, and discusses the multifaceted roles of MOFs in these hybrid systems, and their applications in enzymatic catalysis, photoenzymatic catalysis, and enzymatic electrosynthesis. Regarding living-cell based systems, MOF-cell integration through physical mixing or self-assembly is explored, with analysis of the mechanisms by which MOFs facilitate living cell-based CO₂ fixation. The final section addresses current challenges in the field, including issues related to scale-up and environmental impacts, while providing perspectives on future development directions.