A luminescent nanosensor for Hg(II) based on functionalized CdSe/ZnS quantum dots

Luminescent and stable CdSe/ZnS core/shell quantum dots (QDs) capped with L-carnitine are firstly prepared for optical determination of mercury ions in ethanol. LC capped QDs have desirable dispersibility, uniformity and good fluorescence properties and were characterized by fluorescence spectroscopy, transmission electron microscopy and infrared spectra. The functionalized QDs turned out to exhibit excellent long-term stability. The modified QDs allowed a highly sensitive determination of mercury ions via analyte-induced changes in the photoluminescence of them. A detection limit of 1.8 x 10(-7) M (36.1 mu g center dot L-1) of mercury ions was obtained, while the interfering effect of other ions (including alkali metal ions, alkali earth metal ions, Ni2+, Zn2+, Fe2+, Ag+ and anions such as NO3-, SO42-, CO32- and halogen ions) was negligible even at a very high concentration. The possible mechanism is discussed.