CdSe/CdS quantum dots(QDs) functionalized by thiourea(TU) were synthesized and used as a fluorescent sensor for mercury ion detection.The TU-functionalized QDs were prepared by bonding TU via electrostatic interaction to the core/shell CdSe/CdS QDs after capping with thioglycolic acid(TGA).It was observed that the fluorescence of the functionalized QDs was quenched upon the addition of Hg^(2+).The quantitative detection of Hg^(2+) with this fluorescent sensor could be conducted based on the linear relationship between the extent of quenching and the concentration of Hg^(2+) added in the range of1-300 μg L^(-1).A detection limit of 0.56 μg L^(-1) was achieved.The sensor showed superior selectivity for Hg^(2+) and was successfully applied to the determination of mercury in environmental samples with satisfactory results.
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 The mechanism 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.
