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.