Sensitive detection of cyanazine residues using N, P-co-doped carbon dots/gold nanoparticles (N, P-CDs/AuNPs) fluorescent probe

A novel fluorescent probe based on nitrogen and phosphorus co-doped carbon dots (N, P-CDs) and gold nanoparticles (AuNPs) was developed for the sensitive and selective detection of cyanazine pesticide residues. N, P-CDs exhibited dual excitation wavelengths (460 nm and 490 nm) and a single emission peak at 515 nm. Upon conjugation with AuNPs, the prepared N, P-CDs/AuNPs fluorescent probe demonstrated fluorescence quenching via inner filter effect (IFE) and a remarkable restoration of fluorescence in the presence of cyanazine, attributed to the interaction between cyanide groups and gold nanoparticles. The probe exhibited high sensitivity with a detection limit of 0.14 μmol/L for cyanazine. Selectivity studies showed that the probe was minimally affected by common interfering substances, and recovery experiments in food samples demonstrated good accuracy with spiked recoveries ranging from 93.91 % to 114.30 %. This study provides a promising approach for detecting cyanazine in food samples with high specificity and reliability.