Highly sensitive fluorescence determination of silver ions based on functionalized cadmium telluride nanorods

Water-soluble fluorescent CdTe nanorods (NRs) capped with L-cysteine (Cys) and thioglycolic acid (TGA) were prepared for optical determination of silver ions. These NRs are dispersible, uniform and strongly fluorescent, with an emission wavelength maximum of 585 nm. The fluorescence of such NRs is quenched by silver ions, and this is accompanied by a gradual red shift of the peak from 585 nm to 605 nm. The limit of determination for silver ions is 4.5 nM. The effect of alkali and alkali earth metal ions and of common anions is negligible even at high concentrations. Steady-state fluorescence and UV-vis spectroscopy reveals that competitive binding of Ag ions to Te atoms and to Cys/TGA moieties are responsible for the change in the optical properties observed.