An efficient fluorescent probe for fluazinam using N, S co-doped carbon dots from l-cysteine

Carbon dots doped with nitrogen and sulfur (NSCDs) was prepared from l -cysteine with a hydrothermal method and applied to develop a fluorescent sensor to determine fluazinam . Characterizations of the NSCDs suggest that it provides abundant affinitive sites for recognizing fluazinam through molecular interactions including electrostatic, π-π stacking and hydrogen bonding interactions. Strong inner filter effect (IFE) leads fluazinam to quench the fluorescence of the NSCDs with high efficiency. Under optimized conditions, the fluorescent probe shows very good sensitivity and selectivity in a linear range from 0.05   μM to 4   μM, and the detection limit is calculated down to 10   nM. The proposed fluazinam sensor is demonstrated to be feasible for application in detecting this fungicide in soil and apple samples with satisfactory accuracy. Besides, NSCDs could also be used to fabricate visual paper-based testing stripes under a portable UV lamp with a detection limit as lower as 50   μM. The fluorescent material presented here provides a functional platform for simple yet facile in-field detection of fluazinam in related samples.