MnO₂ Nanosheet-Carbon Dots Sensing Platform for Sensitive Detection of Organophosphorus Pesticides

Carbon dots (CDs) combined with a nanomaterial-based quencher has created an innovative way for designing promising sensors. Herein, a novel fluorescent-sensing platform was designed for sensitive detection of organophosphorus pesticides (OPs). The preparation of CDs was based on one-step hydrothermal reaction of 3-aminobenzeneboronic acid. The fluorescence of CDs can be quenched by manganese dioxide (MnO₂) nanosheets via the Förster resonance energy transfer (FRET). In the presence of butyrylcholinesterase (BChE) and acetylthiocholine, the enzymatic hydrolysate (thiocholine) can efficiently trigger the decomposition of MnO₂ nanosheets, resulting in the recovery of CDs fluorescence. OPs as inhibitors for BChE activity can prevent the generation of thiocholine and decomposition of MnO₂ nanosheets, accompanying the fluorescence "turn-off" of the system. So the BChE-ATCh-MnO₂-CDs system can be utilized to detect OPs quantitatively based on the fluorescence turn "on-off". Under the optimum conditions, the present FRET-based approach can detect paraoxon ranging from 0.05 to 5 ng mL^-1 with a detection limit of 0.015 ng mL^-1. Meanwhile, the present strategy also showed a visual color change in a concentration-dependent manner. Thus, the proposed assay can potentially be a candidate for OPs detection.