Synthesis of Chiral Dual-Stabilizer-Capped CdSe Nanocrystals and Its Application Selective Detection of Hg(II)

Dual stabilizer (D-penicillamine and L-cysteine)-capped CdSe nanocrystals were prepared by direct aqueous synthesis method, and their fluorescence intensities were significantly quenched by the trace amounts of Hg(II). A new method to determine trace Hg(II) was established by using the as-prepared nanomaterials as sensing elements. When the molar ratio of Cd2+(HSe−(D-Pen(L-Cys is adjusted to 1(0.25(2(1.2 at pH 7.5, CdSe/D-Pen/L-Cys possesses a better luminescent strength and stability than CdSe/D-Pen and CdSe/L-Cys. TEM results show that CdSe nanocrystals are spherical particles, and their sizes are about 50 nm and 80 nm. In phosphate buffer solution of pH 7.38, the maximum peak of the fluorescence spectra of CdSe/D-Pen/L-Cys is at 516 nm; the fluorescence could be selectively quenched by Hg(II). The fluorescence quenching was found to be proportional to the concentration of Hg(II), with a remarkable detection limit of 40 pM. The method was applied to determine Hg(II) in different water samples, and the obtained results were in good agreement with those obtained by the standard method. The average recovery was 96.7%-102.5%.