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

Dual-stabilizer (D-Penicillamine (D-Pen) and L-Cysteine (L-Cys) ) capped CdSe nanocrystals were prepared by direct aqueous synthesis method,and trace Hg(Ⅱ) have a significantly quenched their fluorescence intensity.A new method for the determination of trace Hg(Ⅱ) was established based on this.When pH is 7.5 and molar ratio of Cd2 +∶HSe-∶D-Pen∶L-Cys is 1∶0.25∶2∶1.2,CdSe/D-Pen/L-Cys has a better luminescent strength and stability than CdSe/D-Pen and CdSe/L-Cys.TEM shows that the CdSe nanocrystals are spherical particles,and the sizes of the particles are about 50 nm and 80 nm,respectively.In the phosphate buffer solution at pH 7.38,maximum fluorescence peak of CdSe/D-Pen/L-Cys was at 516 nm,the fluorescence could be quenched significantly and selectively by Hg(Ⅱ) .The fluorescence quenching was proportional to the concentration of Hg(Ⅱ),a detection limit of 40 pmol/L was achieved.The method was applied to the determination of Hg(Ⅱ) in different water samples,and the results were in a good agreement with those obtained by the standard method.The average recovery was 96.7%-102.5% .