Monitoring pyrophosphate anions via cobalt(II)modulated fluorescence of cadmium sulfide quantum dots

摘要

In this work, a novel and simple off-on fluorescent sensor is proposed for the selective detection of pyrophosphate (PPi) in an aqueous solution. The sensing approach is realized using fluorescent cadmium sulfide quantum dots (CdS QDs) capped with 3-mercaptopropionic acid, which displayed excellent optical properties and high photostability. The red emission of CdS QDs was significantly quenched in the presence of Co2+ (turn-off) due to the aggregation induced by the coordination between Co2+ ions and carboxyl groups on CdS QDs. However, the continuous addition of PPi can restore the fluorescence (turn-on) due to the competition between PPi and carboxyl groups to coordinate with Co2+ ions leading to the re-dispersion of CdS QDs. Thus a sensitive probing PPi method was successfully established. Under optimized conditions, the proposed fluorescent platform was used for PPi detection in the range of 0.2 to 260 mu M with a detection limit of 35 nM. The fluorescence turn-off/on approach showed a highly selective response to PPi in the presence of 20 different types of species.