Recent Advances in Metal–Organic Frameworks as Functional Coatings for Biosensor Construction

Conventional biosensor coatings face considerable challenges in reconciling high loading capacity, antifouling performance, and long-term stability. Metal–organic frameworks (MOFs), with their ultrahigh surface areas, tunable pores, and abundant unsaturated metal sites, have become important functional coating materials for advanced sensing interfaces. This review focuses on interface engineering strategies for MOF-based biosensor coatings and systematically compares three core construction approaches, namely defect engineering, MOF-on-MOF heterostructures, and interface-assisted fabrication, examining their distinct interfacial regulation logics and applicability under engineering constraints including substrate compatibility, film uniformity, and scalability. The multifaceted interfacial roles of MOF coatings are then categorized across electrochemical, photoelectrochemical, colorimetric, optical fiber, and dual-signal biosensors, covering enrichment-confinement, catalytic transduction, biorecognition protection, and smart gating. Notably, most reported systems remain at the proof-of-concept stage, with insufficient validation in complex biofluids, ambiguous signal transduction mechanisms, and a notable deficiency in systematic assessments of coating adhesion and durability. Future efforts should focus on establishing standardized failure evaluation protocols, adopting AI-driven rational design, and advancing toward multi-target integrated and flexible wearable platforms to bridge the gap between laboratory research and practical diagnostic applications.