▎ 摘　　要

The rational surface functionalization of graphene quantum dots (GQDs) has attracted much attention to extend their application in fabricating bio/chemical sensing platform. In this paper, a GQDs-based copper ions (Cu2+) modulated dual-functional fluorescent probe was developed. The attachment of sulfanilic acid and glutathione onto GQDs through amide linkage to obtained the functionalized graphene quantum dots (termed as SSGQDs). The SSGQDs exhibit dramatically enhanced green fluorescence compared with GQDs. And the fluorescence of SSGQDs was found to be effectively quenched by Cu2+ via aggregation kinetics with the formation of SSGQDs-Cu(II) complex. Sulfide anions (S-2) exhibits a good capacity to remove Cu2+ from SSGQDs and dissociated SSGQDs-Cu(II) complex, as a result the fluorescence of SSGQDs was turned on again. Moreover, the introduction of ascorbic acid (AA) could also induce the fluorescence recovery, because it could reduce Cu2+ into Cu+ and result in the destruction of the SSGQDs-Cu(II) complex. This method can be used for the selective analysis of S2- and AA down to 12.6 nM and 20.3 nM, respectively. Furthermore, the applications of this probe for S2- and AA determination in lake water samples and beverage sample have been demonstrated with satisfactory results. (C) 2017 Elsevier B.V. All rights reserved.