| Quantum dots(QDs) containing with Ag is a three-dimensional size between 1~10 nm novel inorganic semiconductor light-emitting nanocrystals with benefits as photochemical stability, broad excitation spectrum and good biocompatibility, it is widely used in biological cell imaging fluorescent probes, chemical sensors and other fields. In particular, compared to conventional organic dye, QDs containing with Ag as a fluorescent-labeled probes exhibit good photochemical stability, long-lasting and difficult to be degraded optical properties and so on. In addition, along with industrial development and prosperity, heavy metals are widely distributed in the nature of human survival, caused great harm to human health and environment. Traditional detection of heavy metal ions(Hg2+) test analysis method is cumbersome, complex and lengthy and requires expensive, such as complicated equipment electrochemical methods, high performance liquid chromatography. So it is important for human to find economical and convenient method for the detection of heavy metal ions. Emerging fast and economical method for the detection of heavy metal ions- semiconductor QDs containing with Ag photochemical sensor gradually being concerned about environmental science. In this paper, Synthesis of QDs containing with Agusing water-soluble, and discuss the synthesis of the QDs containing with Ag and Ag2S-Zn QDs as the applications of Hg2+ ion fluorescence probe. The main research contents are summarized as follows:1. The photoreduction synthesis of Ag QDs with d-penicillamine, l-penicillamine as ligand. Pen@Ag QDs exhibit uniform size, fluorescence intensity and stable in the environment characteristics, the chiral of pen@Ag QDs can be controlled by changing the UV irradiation time. Meanwhile, hemolysis test showed pen@Ag QDs have better biocompatibility than TGA@Cd Te QDs.2. Using 60 ℃ water phase synthesis of d-pen@Ag2S-Zn QDs. Transmission electron microscopy(TEM), UV absorption spectrum(UV-vis) and fluorescence spectra(PL) were characterized. And we carried out applied research about d-pen@Ag2S-Zn QDs for the detection of heavy metals Hg2+ as fluorescent probes. Using the presence of Hg2+ and d-pen@Ag2S-Zn QDs system, the fluorescence spectra in the scattering peak intensity at a wavelength of 512 nm gradually increased along with Hg2+ concentration increases. Meanwhile, the study of other ions such as K+, Na+, Zn2+, Mg2+, Ca2+, Cu2+, Ba2+ and Sr2+ has no effect on the fluorescence properties. Therefore, we designed a new type of non-toxic, green fluorescent probes to detect Hg2+.3. 120 ℃ hydrothermal synthesis of DHLA@Ag2S QDs. To find the optimal reaction conditions by factor analysis are: nDHLA: nAg NO3: nTAA = 50:1:0.5, p H=9.0. Meanwhile, it can be seen from the fluorescent characterization, the max of reaction time was 180 min. UV-Vis spectra by the same sampling time can be seen as moving in the extension of the wavelength to a longer wavelength, i.e. red shift, it may be generated DHLA@Ag2S quantum dot particle diameter becomes larger. Further it can be seen by XRD and TEM, DHLA@Ag2S QDs are monoclinic type, and the particle diameter of approximately 7 nm; Zeta potentials and particle size distribution of DHLA Ag2 S QDs show negative charge, particle size distribution and stable good performance. Finally, EDX and XPS exhibit the elements of DHLA@Ag2S QDs. Particularly, DHLA@Ag2S QDs prepared in the near infrared region(at a wavelength of 885 nm) photoluminescence. |
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