Gao_2026_Anal.Chim.Acta_1410_345616

BACKGROUND: Although the widespread utilization of nanozyme-based sensing systems in the determination of pesticides, the rational design of carbon dots (CDs)-based nanozymes with superior catalytic activity for multimodal pesticide detection with cross-validation of results remains a challenge. RESULTS: Herein, we engineered Fe-doped CDs (Fe-CDs) with exceptional peroxidase-mimetic activity, whose catalytic performance exhibits significant enhancement compared to undoped CDs. These Fe-CDs catalyze the oxidation of colorless 3,3',5,5'-tetramethylbenzidine (TMB) to its chromogenic oxidized form (oxTMB), which exhibits a characteristic absorption signal and pronounced photothermal effect upon 808 nm irradiation. Concurrently, acetylcholinesterase (AChE) catalyzes the hydrolysis of acetylthiocholine (ATCh) into thiocholine (TCh), a reducing species that inhibits oxTMB production, thereby attenuating both colorimetric and photothermal signals. Notably, organophosphorus (OPs) and carbamate pesticides irreversibly suppress AChE activity, thus blocking TCh generation and restoring the chromogenic reaction alongside a concomitant temperature response. By integrating this cascade catalytic mechanism with the inherent properties of oxTMB, a dual-modal colorimetric and photothermal sensing platform was constructed for detecting the two classes of AChE-inhibiting pesticides, featuring high sensitivity, low detection limits and robust anti-interference capacity. SIGNIFICANCE: This study advances the rational engineering of high-performance peroxidase-like CDs nanozymes, while establishing a dual-modal platform for sensitive detection of OPs and carbamate pesticides. By exploiting dual visual readouts with cross-validated capabilities, this multimodal biosensor transcends the inherent limitations of single-mode sensing systems, substantially enhancing experimental accuracy and reliability. Such innovation presents a promising strategy for pesticide detection in food safety domain.