| Owing to the small size, electronics, catalytic and optical properties, gold nanoparticles and CdS quantum dots acted as the classic nanometer materials have been wildly used in the fields of biomedical imaging, DNA and inorganic metal ion detection since their discovery. In the thesis, we used S2" modified gold nanoparticles to detect the Hg2+in the solution by the resonance scattering technology, and a visual method for Hg2+was further developed based on the color change of this solution. In addition, new analytical methods for Hg2+determination were proposed respectively based on the S2-modified gold nanorods and sulfide-capped CdS quantum dots. Moreover, we studied the interaction between the cadmium-capped CdS quantum dots with the cysteine. The main contents are listed as follows:(1) We had synthesized several sizes of gold nanoparticles and modified them with S2-. After modification, the gold nanoparticles were characterized by Laser Raman Spectra and used for the detection of Hg2+in the aqueous solution. Our results showed the gold nanoparticles aggregated together and the color of the solution changed from red to violet until blue. The enhanced RLS intensities were found to be proportional to the concentration of Hg2+in the range of 0.025-0.25μmol·L-1 with a detection limit (3σ) of 0.013μmol·L-1. This method was successfully used for the detection of environmental samples and there were many merits of this way, such as simple and small measuring structure, high sensitive, fast determination, broaden adaption environment and so on, so having certain application value.(2) We had synthesized pink gold nanorods and modified them with S2-. In the acidic medium, one side of sulfur reacted with the gold nanorods by the covalent binding effect and the other side combined with mercury to form Hg-S bond, so the distance of gold nanorods decreased and the resonance light scattering (RLS) intensities of the system increased greatly. Experiments showed that the enhanced RLS intensities (ΔIRLS) were proportional to the concentration of Hg2+in the range of 0.1-10μmol·L-1. The correlation coefficient of linear equations was 0.9910 with a detection limit of 0.096μmol·L-1.(3) Using sodium hexametaphosphate and sodium citric as stabilizing substances, the sulfide-capped CdS quantum dots had been fabricated in the icewater bath by controlling the initial amount of S2-more than the initial amount of Cd2+. The sufide-capped CdS quantum dots were used as fluorescence probes for the selective determination of trace amounts of Hg2+based on the evident quenching action of Hg2+ on the fluorescences of quantum dots. The effects of buffer type, pH value and CdS quantum dots concentrations were investigated. Under optimum condition, the value of ((Fo-F)/F) upon the addition of Hg2+were found to be proportional to the concentration of Hg2+in the range of 0.05-33μmol·L-1 with a detection limit of 0.08μmol·L-1. Thus, a new fluorometric method for Hg2+based on the sulfide-capped CdS was developed.(4) Controlling the initial amount of Cd2+more than the initial amount of S2-, the cadmium-capped CdS quantum dots were prepared by means of sodium hexametaphosphate and sodium citric as stabilizing substances in the icewater bath. The cadmium-capped CdS quantum dots were used as fluorescence probes for the selective determination of cysteine. Our results showed that the cysteine could increase the fluorescence intensities of the CdS quantum dots. In the B-R buffer solution with pH value of 2.87, the value of ((Fo-F)/Fo) upon the addition of Hg2+were found to be proportional to the concentration of cysteine with a detection limit of 0.01μmol·L-1. Our results showed that there was a best selectivity and satisfactory recovery.
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