Polygonatum cyrtonema Hua residue carbon quantum dots as fluorescent probes for detecting organophosphorus pesticide residues

The detection of pesticide residues is critical for ensuring standardized cultivation of traditional Chinese medicine (TCM). Conventional methods are often complex and insufficiently sensitive. Carbon quantum dots (CQDs), which exhibit superior fluorescence properties, were proposed for sensitive pesticide residue detection via fluorescence signal modulation. In this study, CQDs were synthesized from Polygonatum cyrtonema Hua residue using a one-step hydrothermal method, with optimal conditions determined through response surface methodology. The structure, optical properties, and stability of the Polygonatum cyrtonema Hua-derived CQDs (PC-CQDs) were systematically characterized. A novel fluorescent sensor was developed by exploiting the Fe³ ⁺-induced quenching effect on PC-CQDs for detecting organophosphate pesticide residues in Polygonatum cyrtonema Hua. The system exhibited strong linear correlations for glyphosate, toxic fluorophosphate, and chlorpyrifos, with recovery rates ranging from 92.14 % to 101.81 %, demonstrating its applicability for organophosphate pesticide monitoring in TCM.