Superior Oxidase-Mimetic Activity of Co-MOF Nanozyme for Smartphone-Based Visually Colorimetric Assay of Mancozeb

Mancozeb (MCZ), a widely used fungicide in agricultural production, has been reported as an environmental endocrine disruptor, posing serious risks to ecosystems and human health. In this work, multivalent Co-MOF nanozymes (MVCM) with excellent oxidase-like activity were synthesized, which can promote the oxidation of 2,2′-azino-bis-(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) into a blue oxidative product (ABTS•+), with an obvious absorption peak at 415 nm. With the addition of MCZ, the ABTS•+ was reduced to colorless ABTS through the REDOX reactions between MCZ and ABTS•+. Based on the unique reducing behavior of MCZ, a nanozyme-based colorimetric detection platform was proposed for the detection of MCZ, with a linear range of 3–27 μM and a detection limit (LOD) of 0.15 μM. Furthermore, the sensor was integrated with smartphones and test strips, establishing a portable smartphone-based platform for the real-time, on-site, and visual quantitative detection of MCZ. The detection concentration range was 15–90 μM, with LOD as low as 15 μM. The assay exhibited high adaptability in practical applications. In summary, this work provided a simple, accurate, and low-cost approach for visual determination of MCZ without complicated instruments and procedures.