Ag/CuTb₂O₂ nanozyme-based dual-mode biosensor with self-validating function for ultrasensitive detection of...

In this study, a dual-mode electrochemiluminescent-colorimetric (ECL-colorimetric) biosensor based on Ag/CuTb₂O₂ nanozyme was developed for the ultrasensitive detection of trichlorfon and other organophosphorus pesticides (OPs) by inhibiting acetylcholinesterase (AChE). The Ag/CuTb₂O₂ composite, prepared via electrospinning and in-situ growth, exhibited high conductivity and superior peroxidase-like activity, acting as a dual-signal amplifier. In the ECL mode, it immobilized Ru(bpy)₃²⁺ and boosted the co-reactant pathway; in the colorimetric mode, it catalyzed H₂O₂-mediated oxidation of TMB. Based on AChE inhibition, trichlorfon reduced ECL intensity by decreasing thiocholine production and enhanced colorimetric signals by consuming thiocholine. This dual-signal self-validation improved detection reliability. The sensor achieved a linear range of 1 × 10^-12-1 × 10^-6 mol L^-1 with LOD of 3.33 × 10^-13 mol L^-1 (ECL) and 30-5000 ng mL^-1 with LOD of 10 ng mL^-1 (colorimetric). It also responded to other OPs and gave satisfactory recoveries in vegetable samples, providing a reliable method for food safety monitoring.