Silver ions involved fluorescence “on–off” responses of gold nanoclusters system for determination of carbendazim residues in fruit samples

Herein, a fluorescence "on-off" system was developed for monitoring carbendazim (CBZ) residues in fruit samples, based on glutathione-gold nanoclusters (GSH-Au NCs) and silver ions (Ag+). First, the fluorescence intensity of GSH-Au NCs was greatly enhanced (turn on) with aggregation-induced emission enhancement (AIEE) effect in the presence of Ag+, then fluorescence quenching occurred (turn off) with adding CBZ by the chelation between CBZ and Ag+. The quenching degree was well linearly dependent on CBZ concentration covering from 0.5 to 20 μM. Moreover, the GSH-Au NCs-Ag+ system exhibited superior selectivity towards CBZ and was sensitive for the determination of CBZ in apple and orange juices with a low detection limit of 0.12 μM. The recoveries of CBZ spiked in fruit samples ranged from 81.0 % to 111.4% with the relative standard deviations less than 6.6%, demonstrating its great potential for monitoring CBZ residues in fruit samples.