The Synthesis, Modification And Dynamics Study Of Quantum Dots

Many of the activities of life are conducted in the nanometer scale, which is "invisible". In the past few decades, technology has made immeasurable strides to enable visualization, identification, and quantitation in biological systems by the nanotechnology, especially by the creation of new nanomaterials with superior performance. Quantum dots, as an alternative to organic dyes and fluorescent proteins, have a series of obvious advantages, such as higher quantum yield and more stable against photobleaching, so they were widely used in bio-sensing and biological imaging including nucleic acid sensing and in vitro/vivo imaging. Therefore the study of the synthesis, modification and biological coupling of high-quality tunable quantum dots show great significance to the biological applications of QDs. The main works in this thesis are summarized as follows:(1) Adopting dihydrolipoic acid (DHLA) as modifying reagents, high quality water-soluble QDs was achieved by the modification of the ZnS-AgInS2 (ZAIS) quantum dots. It was found that there was no significant change in the emission peak and fluorescent intensity through the characterization. The influence of the pH and the concentration on the QDs was also investigated, and found that as the pH value increased, the fluorescence intensity gradually decreased, and as the lower concentration, the fluorescence emission peaks were gradually blue-shifted.(2) Prepared the core/shell QDs by coating the ZAIS QDs with a thin layer of ZnS. Fluorescence quantum yield of the QDs increased slightly, while the size and appearance did not change significantly after the capping.(3) The QDs-PrP conjugates were formd via the high affinity between Zn metal and histidine. It was found that the QDs fluorescence intensity could be enhanced through the reaction and then be quenched by the Ni2+ with high concentration. The diffusion dynamics parameters of the QDs and conjugates in the water were also estimated by fluorescence microscope system and no significant difference was found between them.