Continuous Detection of Cobalt Ions and Pyrophosphates by NAC-CdTe Quantum Dots Fluorescence Probes

In this work, a simple and sensitive N-acetyl-L-cysteine (NAC)-covered CdTe quantum dots (NAC-CdTe QDs) fluorescence probe for continuous detection of Co 2+ and pyrophosphate ions (PPi, P 2 O 7 4− ) was synthesized. The fluorescence of the quantum dots was significantly quenched by Co 2+ through the coordination of Co 2+ and the carboxyl groups on the NAC-CdTe quantum dots. Interestingly, the combination of NAC-CdTe quantum dots with Co 2+ yields a new fluorescence probe of Co 2+ -modified NAC-CdTe QDs (Co 2+ @NAC-CdTe). The addition of PPi restored the fluorescence due to the competition between PPi and carboxyl groups with Co 2+ causing Co 2+ to detach from the surface of Co 2+ @NAC-CdTe quantum dots. Thus, a sensitive and reversible detection of Co 2+ and PPi had been successfully established. The Co 2+ @NAC-CdTe quantum dots fluorescence probe exhibits excellent selectivity and high sensitivity toward PPi detection with low detection limit of 0.28 μM. In addition, the novel fluorescence probe was successfully applied to detect the concentration of PPi in environmental water samples and in-vitro cells imaging.