Covalent Organic Frameworks for Enzyme Immobilization: Synthesis, Pore Structure Modification, and Applications

Immobilized enzymes constitute a class of composite biocatalysts whose performance is governed by both enzyme molecules and carrier materials. Recent advances in materials science have yielded diverse novel porous materials, with covalent organic frameworks (COFs) emerging as particularly promising candidates for enzyme immobilization carriers. This review systematically categorizes COF synthesis strategies based on elemental composition, encompassing boron-containing, nitrogen-containing, and novel metal-containing COF variants. Enzyme immobilization techniques on COFs are classified into postsynthesis and presynthesis approaches. Furthermore, methodologies for constructing diverse building blocks and critical linkage structures are summarized, alongside detailed elucidation of pore structure modulation techniques─including topological design, template-assisted methods, and defect engineering─employed to enhance compatibility with enzyme dimensions. Finally, emerging types and application scenarios of immobilized enzyme-COF composite systems are analyzed, emphasizing the critical importance of rational design and recoverability in advancing practical application potential.