A bimetallic nanozyme with high peroxidase-like activity for visual detection of organophosphorus pesticides

The detrimental effects of organophosphorus pesticides residues in food on human health demonstrate the crucial need for advanced detection method. To overcome the limitations of existing techniques, this study introduces a novel colorimetric approach combined with nanozyme technology for the detection of organophosphorus pesticides residues. Specifically, a bimetallic metal-organic framework (MOF) incorporating Co (II) and Mn (II) as metal nodes was developed, exhibiting enhanced synergistic properties. This Co/Mn-MOFs serves as a highly efficient peroxidase-like (POD-like) nanozyme, enabling the construction of a simple, highly sensitive colorimetric detection platform. The platform demonstrates exceptional performance in the "switch-on" detection of chlorpyrifos (CPF), achieving a linear detection range of 10-200 nM and a limit of detection (LOD) of 9.84 nM. To further enhance practicality, the platform was adapted into a portable test kit comprising a test swab and a processing tube. When equipped with a color-reading mobile application, the kit achieves an impressive LOD of 12.59 nM for CPF detection. The results highlight the robustness and reliability of this colorimetric method, validating its effectiveness for real-world applications. This work not only presents an innovative strategy for utilizing bimetallic MOFs as highly efficient POD-like nanozymes, but also showcases their exceptional potential in the sensitive and practical detection of organophosphorus pesticides.