Trimetal–Organic Framework-Derived Diatomic Nanozymes-Driven Cascaded Signal Sensitization Intelligent Flexible Sensors for In Situ Detection of the Pesticide Residue

Specific in situ detection of pesticide residues is crucial for environmental safety and scientific pesticide management. Here, we developed a portable cascade signal sensitization intelligent flexible sensor using trimetal–organic framework-derived Pt–Cu diatomic nanozymes (PtCuSA@TriMOF). The PtCuSA@TriMOF reduces the H2O2 reduction energy barrier via cocatalysis, oxidizing TMB to generate dual-mode signals: colorimetric and photothermal. Carbosulfan-specific detection is achieved through acidic hydrolysis, which breaks its N–S bond to generate sulfide ([SH]). These products scavenge hydroxyl radicals (•OH) and inhibit the Pt–Cu bimetallic active sites, establishing a dual-inhibition mechanism that ensures high specificity. With the high dispersibility of the flexible paper base, the liquid detection environment formed a cascade sensitization system. Unlike previous detection technologies, the homemade intelligent flexible reading device can flexibly switch between the built-in light source of the dark box and the reading software on the smartphone to select detection methods according to different scenarios, and the detection limits are 4.2 nM and 5.7 nM. This provides a solid theoretical basis for in situ specific detection of environmental pollutants caused by pesticide spraying.