Determination of silver ion based on the redshift of emission wavelength of quantum dots functionalized with rhodanine

A simple and selective method for the determination of silver ions was developed by utilizing the redshift in emission wavelength of the core-shell CdSe/CdS quantum dots (QDs) functionalized with rhodanine upon the addition of Ag+. A linear relationship was observed between the shift and the increase in concentration of Ag+ in the range of 0.0125-12.5 μmol/L. Themechanism of the red-shift was investigated and suggested that the coordination between Ag+ and rhodanine on the QDs surface caused an increase of particle size, which resulted in the red-shift of the QDs' emission wavelength. A detection limit of 2 nmol/L was achieved. The developed method showed superior selectivity and was successfully applied to the determination of silver in environmental samples.