Abstract: On-site rapid detection has become a key direction in modern environmental monitoring, overcoming the limitations of traditional methods that are often costly, complex, and instrument-dependent. In this context, the search for materials with high sensitivity, selectivity, and practicality is paramount. Metal-organic framework-based nanozymes (MOF nanozymes) have emerged as highly promising functional materials. They uniquely integrate nanomaterial advantages—large surface area, tunable porosity, and abundant active sites—with intrinsic enzyme-like catalytic activities, offering high stability, low cost, and ease of functionalization. Compared with natural enzymes, MOF nanozymes exhibit superior resistance to harsh conditions (extreme pH, high temperature, high ionic strength) and avoid denaturation and inactivation, making them particularly suitable for field applications where controlled laboratory settings are unavailable. Furthermore, their structural designability allows precise modulation of catalytic performance, enabling targeted optimization of enzyme-like activities through rational selection of metal nodes and organic linkers. MOF nanozymes can mimic various natural enzymatic activities, including peroxidase-like (POD), oxidase-like (OXD), catalase-like (CAT), and superoxide dismutase-like (SOD) activities. This versatility enables them to catalyze reactions of multiple chromogenic substrates, such as TMB, OPD, and ABTS, producing distinct color changes that form the basis for colorimetric sensing. Depending on the nanozyme design and reaction conditions, catalytic processes can be finely tuned by adjusting particle size, morphology, surface modification, or pore structure to achieve optimal detection performance. The high sensitivity and selectivity of these nanozymes facilitate the efficient detection of a wide range of environmental pollutants, including toxic heavy metal ions, persistent organic pollutants, and harmful pesticide residues. The detection mechanism typically relies on specific interactions between the analyte and the nanozyme active sites, which either enhance or inhibit catalytic activity, generating a concentration-dependent colorimetric signal. Such analyte-induced modulation enables simple, rapid, and cost-effective sensing platforms well suited for on-site deployment and rapid screening. This review comprehensively summarizes recent advances in the development and application of MOF nanozymes in environmental analysis. It systematically discusses their classification, categorizing them into pure MOF-based materials, MOF composites, and MOF-derived materials, with elaboration on synthesis strategies and structural characteristics. The review elaborates on the catalytic mechanisms, including electron transfer pathways and reactive oxygen species generation, and highlights their applications in colorimetric detection of key environmental pollutants. The discussion covers how pore size, defect engineering, surface chemistry, and environmental conditions (pH value and temperature) affect catalytic efficiency and reaction kinetics. Particular attention is given to structure-activity relationships governed by metal nodes, organic linkers, and post-synthetic modifications, revealing how these factors influence catalytic performance and selectivity. Furthermore, it explores pollutant recognition mechanisms, emphasizing interfacial interactions such as electrostatic forces, coordination bonding, hydrogen bonding, and π-π stacking that govern detection selectivity and sensitivity. Understanding these interactions is essential for designing nanozymes with tailored recognition capabilities. Based on current research progress, this review proposes that future efforts should focus on functional integration and performance enhancement. Specifically, developing multifunctional MOF nanozymes with multiple enzyme-like activities will enable multi-mode synergistic detection to improve detection accuracy and reliability. Key challenges include ensuring biocompatibility and biosafety, developing green, low-cost, and scalable synthesis methods, and improving sensor stability in complex environmental matrices (natural water bodies, soil extracts, biological samples). Addressing these challenges requires interdisciplinary efforts across materials chemistry, analytical chemistry, environmental engineering, and toxicology. Overcoming these hurdles will promote broader applications of this technology in rapid on-site pollutant detection, ultimately contributing to more effective environmental monitoring, early warning systems, and public health.

Key words: metal-organic framework(MOF)-based nanozymes, colorimetric sensing detection, structural classification, enzyme-like activities, environmental pollutants