Preparation Of Bioanalysis Fluorescence Quantum Dots And The Primary Studies Of Their Phase-Transfer

As an eminent representation of nanotechnology , quantumdot has caught great interest s of scientist s in physics , chemist ry ,material science , and biology extensively. Although its application tolife science has just been explored , valuable progresses have beenachieved in both biomacromolecule labeling and coding recently.Since 1997, with the improvement of synthesis of nanocrystals, theyare more and more used as biological fluorescent tags, due to theirattractive qualities as fluorescent tags: broad excitation spectrum,narrow emission spectrum, precise tenability of their emission peak,longer fourescence lifetime than organic flourophores and negligiblephotobleaching. To apply fluorescence nanocrystals in boilablling, quantum dotsynthesis and the surface function of nanocrystals is the key problem.Firstly, only synthesizing high quality quantum dot can provide theresource for application. Secondly, the nanocrystals synthesized inorganic phase are generally overcoated with nonpolar group, whichresults in the nonbiocompatible of nanocrystals. So the importantproblem of application fluorescence as biomarker is the transfer ofthe anocrystals from hydrophilic surface to hydrophobic surface. Thesurface of nanocrystals must provide some surface groups to couplethe nanocrystals with biological molecules. Thus, in the success ofresolving the their surface problem, fluorescence nanocrystals may beapplied in biological and biomedical.My dissertation is focused on the preparation of high qualityfluorescence nanocrystals and transfer them into aqueousenvironment and using them as biological fluorescent tags. Nowsome new results are obtained from our experiments. The mainresults are outlined as followings:1. The synthesis of QDs(quantum dots) and the studies on theircharactersWe synthesize CdSe and CdSe/ZnSe QDs inTOPO/HDA,and characterize the QDs by UV-vis spectra,photoluminescence spctra and transmission electron microscopy,etc.. How the shell thickness affect the quantum yield aredisscused.The QDs synthesized in ODE , compared with the QDssynthesized in TOPO/HDA the QY is higher and the QDs havenarrower size distribution.2. The phase transfer of CdSe/ZnSe nanocrystals with hydrophobicsurface and the studies on encapsulation mechanismTo apply fluorescence nanocrystals in biological, thesurface of nanocrystals from hydrophobic quality to hydrophilicquality with some groups coupling with biological molecules isnecessary. In our experiment, liposome encapsulated fluorescencenanocrystals is firstly used by the hydrophobic-hydrophobicinteraction of phoslipid and surface ligand of nanocrystals. Thus,nanocrystals are encapsulated within liposome and some surfacegroups were provided. It provided a simple but efficiency methodto couple nanocrystals with biological molecule.We first time use a triblock copolymer with an 8-carbonside chain encapsulate QDs. Through this method we transferQDs into ethanol. It is a more efficiency method to couplenanocrystals with biological molecule.