Diethyldithiocarbamate functionalized CdSe/CdS quantum dots as a fluorescent probe for copper ion detection.

A new fluorescent probe for copper ion detection is reported that it is based on the quenching of the fluorescence of the diethyldithiocarbamate (DDTC)-functionalized quantum dots (QDs) in the presence of copper ions. DDTC was bound to the QDs via the surface ligand exchange to form DDTC-QDs conjugates following the capping of 2-mercaptoacetic acid on the core-shell CdSe/CdS QDs. It was found that the fluorescence intensity of the conjugates was quenched after coordinated with Cu(2+). A linear relationship existed between the extent of quenching and the concentration of copper in the range of 0-100 μg L(-1), with a detection limit of 0.29 μg L(-1) (3σ). The DDTC-functionalized QDs showed excellent selectivity for Cu(2+) over other metal cations. The fluorescent probe was successfully used for the determination of copper in environmental samples.