Stable and water-soluble cadmium telluride quantum dots (CdTe QDs) have been employed for ultra-sensing exclusive to water soluble Ag(I). For this purpose we have designed and synthesized thiolactic acid (TLA) capped exquisite CdTe QDs having exclusive selectivity for silver. The limit of detection (LOD) of Ag(I) is 50 nM . The pendant methyl group of TLA effectively impedes the precursor aggregation by inhibiting the secondary coordination of carboxyl oxygen of mercapto acid with the surrounding Cd(II), and this results in highly luminescent TLA-CdTe QDs. This pendant methyl group of TLA also facilitates exclusive surface adsorption of QDs by incoming metal and renders sensing selectivity. Selective adsorption of silver on TLA-CdTe QD surface provides a turn-off photoluminescence-based assay for sensitive detection of Ag(I) without any interference of other commonly coexisting metal ions. Furthermore, analyses of environmental water samples spiked with Ag(I), demonstrate immense practical potential of our TLA-CdTe QD sensor for the detection of silver in real samples. The results also unveiled the possible origin of the sensing selectivity for metal ion by TLA-capped QDs which can serve in the design and selection of appropriate capping in achieving the desired sensing selectivity.
- Ag(I) sensing
- Capping ligand
- Selective-ultrasensitive detection
- TLA-CdTe quantum dots