Cysteamine CdS quantum dots decorated with Fe3+ as a fluorescence sensor for the detection of PPi

A new sensitive and selective fluorescence sensor for the detection of pyrophosphate (PPi) in aqueous media based on the Fe3+ decorated cysteamine CdS QDs ([Cys-CdS QDs]–Fe3+) was proposed. The presence of PPi can induce the fluorescence quenching of [Cys-CdS QDs]–Fe3+ due to the high formation constants between the phosphate group and Fe3+. Because the complex between Fe3+ and PPi acts as an efficient quencher, the concentration of PPi can be evaluated by tracking the degree of fluorescence quenching. The fabricated sensor was optimized to obtain the best sensor selectivity and sensitivity. Under optimal conditions, a linear relationship between the fluorescence response and the concentration of PPi was established in the range of 0.5–10 μM. The limits of detection and quantitation for PPi were found to be 0.11 and 2.78 μM, respectively. Furthermore, the proposed sensor exhibited high selectivity toward PPi relative to other common anions. The proposed sensor was successfully applied to the detection of PPi in urine samples with satisfactory results.