The Biological Effect Research Of CdSe And Ag₂Se QDs

In this paper, the water-soluble mercaptopropionic acid(MPA) covered cadmium selenide quantum dots and the glutathione-silver selenide quantum dots were synthesized, and their cytoxicity on living cells Tetrahymena and E.coli was also investigated. Details are as follows:1. Water soluble cadmium selenide quantum dots were prepared by phase-transfer method. Oil-soluble quantum dots were transferred to water-soluble by the ligand exchange. By UV-visible absorption spectroscopy(UV-vis), fluorescence emission spectra, X-ray diffraction(XRD) and dynamic light scattering(DLS), the synthesized products were characterized. Results showed that the product synthesized in this way had a good solubility in water and a uniform particle size distribution. Water soluble silver selenide quantum dots were also prepared, and the effect of the specific synthesis conditions such as the materials' ratio, the solution p H and the reflux time for the quantum dot on the size distribution was explored.2. The toxicity of prepared cadmium selenide quantum dots on the biological model was investigated. The effects of Cd Se quantum dots concentrations and sizes on Tetrahymena and E.coli were talked about. Cd Se quantum dots inhibited normal cells growth and metabolism significantly, and with the increase of quantum dots concentrations, the toxic effects enhanced. In this paper, quantum dots with the diameter of 2 nm, 3 nm, and 5 nm were used to research the influence of particle size on biological cells. With the increase of particle size, quantum dots toxicity decreased gradually. By the methods of microcalorimetry, fluorescence polarization, the attenuated total reflectance-Fourier transform infrared spectra, field emission scanning electron microscopy and fluorescence microscopy, the specific toxicity mechanism was discussed.3. The toxicity of the water-soluble silver selenide quantum dots on the biological models Tetrahymena and E.coli was also explored. Cytoxicity of different concentrations of silver selenide quantum dots were compared and the results indicated that silver-selenide quantum dot was a kind of less toxic near infrared spectroscopy nano materials.