Some Applications Of Quantum Dots Characteristics

In the studied of materials, people found that there is a stage called mesoscopis areas between macro areas and micro areas, including micron, submicron, nanometer and cluster materials. Due to theirs small dimension, they have especial photophysical properties. A kind of materials in mesoscopis areas is well known quantum dots (QDs) whose size is the same as Bohr radius. Compared with traditional organic dyes, QDs are paid more attention because of its unique quantum effects. QDs own many advantages that are broad and consecutive excitation spectra, narrow and symmetrical emission spectra, tunable size-dependent emission, strong resistance to photobleaching capacity, high quantum yields and good biological compatibility. QDs have been widely studied in biomedicine, chemiluminescence, fingerprints detection and so on. A plenty of articles have been reported about QDs'synthesis and applications. Based on predecessors'research results, this thesis makes a preliminary explore on quantum dots used in biomedicine and material science.The thesis consists of two parts. The first is outline which describes the definition, basic characters, fluorescence characteristics, luminescence mechanism, synthesis methods, biological compatibility and application of quantum dots.The second part is research report which mainly contains three chapters:1. Preparation of TGA, L-Cys and GSH-capped CdTe QDs and studied theirs biological compatibilityTGA-capped CdTe QDs, L-Cys-capped CdTe QDs and GSH-capped CdTe QDs were prepared in aqueous solution and characterized by FL spectra and Uv-vis absorption spectra respectively. In order to use these QDs in life sciences, theirs biological compatibility were evaluated by hemolysis experiment in vitro. The results showed that in given experimental condition, all QDs have good biocompatibility: GSH-capped CdTe QDs>L-Cys-capped CdTe QDs>TGA-capped CdTe QDs.2. Prepared PVA-S-capped CdTe QDs and its biological compatibilitySeeking for better biocompatibility of QDs, PVA reacted with TGA to produce PVA-SH. We used NaBH4 to reduced disulfuram to mercapto-group and determined the amount of mercapto-group. What's more, PVA-S-capped CdTe QDs were prepared in aqueous solution and its synthetical factors were optimized. Finally, we also valued theirs biocompatibility by the above method. The results implied that the biological compatibility of PVA-S-capped CdTe QDs was superior to that of GSH-capped CdTe QDs.3. The application of quantum dotsHydrophilic GSH-capped CdTe QDs were transferred into oleophilic QDs, which can mix with PMMA homogeneously in order to prepare QDs/PMMA compound. Quantum dots hydrogel was prepared by dehydration reaction between GSH-capped CdTe QDs and PVA. These materials may stop Cd2+ letting out which extend the application of QDs.