The Synthesis Of Fluorescence Nanocrystals And The Primary Studies Of Their Application In Immunology

Recently with the development of nanotechnology, semiconductor nanocrystals have been paid more and more attention because of their unique optical and electronic properties. Since 1997, with the improvement of synthesis of nanocrystals, they are more and more used as biological fluorescent tags, due to their attractive qualities as fluorescent tags: broad excitation spectrum, narrow emission spectrum, precise tenability of their emission peak, longer fourescence lifetime than organic flourophores and negligible photobleaching.To apply fluorescence nanocrystals in boilablling, the surface function of nanocrystals is the key problem. On the one hand, the nanocrystals synthesized in organic phase are generally overcoated with nonpolar group, which results in the nonbiocompatible of nanocrystals. So the important problem of application fluorescence as biomarker is the transfer of the nanocrystals from hydrophilic surface to hydrophobic surface. On the other hand, the surface of nanocrystals must provide some surface groups to couple the nanocrystals with biological molecules. Thus, in the success of resolving the their surface problem, fluorescence nanocrystals may be applied in biological and biomedical. My dissertation is focused on the preparation of high quality fluorescence nanocrystals and encapsulating CdSe nanocrystals in liposome in order to transfer them into aqueous environment and using them as biological fluorescent tags. Now some new results are obtained from our experiments. The main results are outlined as followings:1.The synthesis of CdSe nancrystals and the studies on their growth mechanismThe change of temperature and ligand effecting on the size of CdSe nanocrystals under the condition of Cd:Se=1:10were carefully studied by UV-vis spectra, photoluminescence spctra and transmission electron microscopy, etc.. The course and mechanism of CdSe nanocrystal are disscused. 2. The surface passivation of CdSe nanocrystals and the studies on the formation mechanism of core-shell nanocrystalThe surface of bare CdSe nanocrystals exits lots of defect state so that the nanocrystals are easy to be oxided and the fluorescence of they are quenched. The passivation of CdSe nanocrystals surface is necessary in order to enhance their fluorescence efficiency. In our experiments, ZnSe, ZnO was chosen to passivate bare CdSe nanocrystals due to their more wide band gap. CdSe/ZnSe core/shell nanocrystals were synthesized by one-pot method. This experiment is different from traditionally two-step method of formation core-shell nanocrystal. Zn precursors were directly injected into the CdSe system and ZnSe may be formed with the center of CdSe nanocrystals due to the excess of Se precursor. ZnSe passivated CdSe nanocrystals and improved the photoluminescence efficiency of CdSe nanocrystals. We firstly synthesized CdSe/ZnO core-shell nanocrystals in heterogeneous solution. ZnO shell layer grow on the surface of CdSe nanocrystal. On the one hand, ZnO could decrease the surface defect of CdSe nanocrystals and improve the photoluminescence of CdSe nanocrystals. On the other hand, the –OH and –COOH groups exited on the surface of CdSe/ZnO provide the bridge of core-shell nanocrystals in ethanol. 3, The phase transfer of CdSe/ZnSe nanocrystals with hydrophobic surface and the studies on encapsulation mechanism High quality CdSe nanocrystals are generally synthesized in organic solution. That results in the formation of hydrophobic surface due to the exit of hydrophobic surface ligand, which limited the application of fluorescence nanocrystals in biological. To apply fluorescence nanocrystals in biological, the surface of nanocrystals from hydrophobic quality to hydrophilic quality with some groups coupling with biological molecules is necessary. In our experiment, liposome encapsulated fluorescence nanocrystals is firstly used by the hydrophobic-hydrophobic interaction of phoslipid and surface ligand of nanocrystals. Thus, nanocrystals are encapsulated within liposome and some surface gr...