A highly sensitive ratiometric fluorescent sensor for copper ions and cadmium ions in scallops based on nitrogen doped graphene quantum dots cooperating with gold nanoclusters

Based on the electrostatic interaction, we constructed a ratiometric fluorescence nanomixture of graphene quantum dots-gold nanoclusters (GQDs-AuNCs) for the quantitative detection of Cu 2+ and Cd 2+ . When Cu 2+ or Cd 2+ was added into the reaction system, the fluorescence of GSH-AuNCs at 565 nm can be quenched by Cu 2+ and enhanced by Cd 2+ while the intensity of N -GQDs at 403 nm stayed constant. Under the optimized conditions, the fluorescence intensity ratio (I 565 /I 403 ) of the GQDs-AuNCs system was proportional to the concentration of Cu 2+ and Cd 2+ in the range of 8×10 −8 mol/L-6×10 −6 mol/L and 1×10 −6 mol/L-4×10 −5 mol/L, respectively, with detection limits of 4.12×10 −9 mol/L and 9.43×10 −7 mol/L, respectively. In the presence of Cu 2+ and Cd 2+ , the paper-based vision sensor would produce visible fluorescent color changes, which can be used for rapid detection on site. The method has been successfully applied to the determination of Cu 2+ and Cd 2+ in scallops with satisfactory results.