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 Cu2+ and Cd2+. When Cu2+ or Cd2+ was added into the reaction system, the fluorescence of GSH-AuNCs at 565 nm can be quenched by Cu2+ and enhanced by Cd2+ 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 Cu2+ and Cd2+ in the range of 8x10(-8) mol/L-6x10(-6) mol/L and 1x10(-6) mol/L-4x10(-5) mol/L, respectively, with detection limits of 4.12x10(-9) mol/L and 9.43x10(-7) mol/L, respectively. In the presence of Cu2+ and Cd2+, 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 Cu2+ and Cd2+ in scallops with satisfactory results.

Automated summary

By constructing a GQDs-AuNCs system based on electrostatic interaction, a sensitive and quantitative detection of Cu2+ and Cd2+ was achieved. The method allows for rapid on-site testing and showed satisfactory results in the determination of Cu2+ and Cd2+ in scallops.