A turn-on fluorescence biosensor for sensitive detection of carbaryl using flavourzyme-stabilized gold nanoclusters

Carbaryl contamination in food products has attracted much attention due to its threatening effects on human health. In this study, a novel flavourzyme-stabilized gold nanoclusters (Fla-AuNCs) biosensor with an average diameter of 1.37 nm was designed by a one-pot biomineralization method, which displayed blue fluorescence with an emission wavelength of 420 nm upon excitation at 360 nm. Meanwhile, it showed excellent photo stability and maintained more than 90% of its original fluorescence intensity under an ultraviolet lamp for a period of 60 min or after storage in water solution at 4 degrees C for one month. Interestingly, the Fla-AuNCs acted as a fluorescent biosensor showing evident fluorescence enhancement after the addition of carbaryl via AIE and exhibited good linearity in the range of 25-200 nmol/L (R-2 = 0.9958), with a detection limit of 2.34 nmol/L. Moreover, the sensing method was successfully utilized for the determination of carbaryl in fruit and vegetable samples with satisfactory recoveries of 95.4-103%. Hence, this study expands the range of protein templates for the synthesis of nanoclusters and develops a novel biosensor for agricultural product safety and monitoring.