Synthesis And Characterize Of CdTe Quantum Dots And The Research On Its Biology Application

Nanomaterials, which are different from their corresponding bulk materials, have the novel optic, electric and magnetic properties. In this dissertation, the synthesis, characterization and biological labeling of some nanoscale semiconductor materials have been systematically studied. The main research results are shown as follows:(1)Emission-tunable CdTe quantum dots were synthesized Under open-air conditions。Various reaction conditions that affected the optical properties of CdTe nanoparticles were studied, including the time of reaction and the pH. Furthermore, these nanoparticles were characterized by High resolution electron microscopy, fluorescence spectra and UV-Vis spectroscopy, the UV-Vis spectroscopy provide information about the progress of nucleation and growth of the particles. The prepared CdTe quantum dots were further observed on their photochemical stability. The result shows that illumination can greatly increase the photoluminescence of CdTe quantum dots. Illumination-assisting photoluminescence enhancement effects were explained by the photochemical degradations of thioglycolic acid on the surface of quantum dots. Sulfide ions may react with cadmium ions on the CdTe particle surface and form a shell structure of CdS. The formation CdS shell on the CdTe will effectively passive the CdTe surface and give rise to a great increment in photoluminescence intensity. (2) Based on the above work, CdTe quantum dots were coated SiO2, CdTe/SiO2 fluorescence microspheres were synthesized,and fluorescence spectra of CdTe and CdTe/SiO2 fluorescence microspheres were studied. Polylysine was used as template and the CdSe/ZnS were incorporated into the microspheres. Under laser confocal microscopy, it's clearly to see that the luminescent quantum dots was well-proportioned in the microsphere. The stability of the microsphere was also examined and results shows that the microspheres were very stable. (3) Fluorescent Probes based on semiconductor quantum dots (QDs) were successfully synthesized for tumors targeting and imaging in vivo. The structural of fluorescent probes design involves conjugating hydrophilic CdTe QDs to folic acid to target the folate-binding protein, this molecule is the folate receptor that is overexpressed on the surface of many tumoral cells. Folate targeting improved the specificity of QDs for labeling tumor. Intracellular distribution of QD staining was characterized with fluorescence microscopy. Derived images of tissues lableled with QDs-FA probes generally show bright fluorescence, whereas images of tumors only with QDs display little or no fluorescence. These findings suggest the use of QDs via folate as an effective probe for detecting tumors and long-term labeling of cells.