Synthesis Of Water-Soluble Quantum Dots And Its Bio-Application

Due to the prospect of biological application, water-solube quantum dots (QDs) have been attracted much attention in recent years. The preparation of QDs in aqueous-phase is simple, controllable, low cost, high repetitive and large-scale preparation, and the charge and properties of surface can be controlled, it is easy to introduce functional molecule, while its surface is coated with a layer of water-soluble grooming groups (such as amide, carboxyl), can be directly connected with biological molecules, Which make QDs become a very promising biological fluorescent probe.Based on good biocompatibility of PAMAM dendrimers and water-soluble QDs, preparation of good biocompatibility and high stability fluorescent nanoprobe, development of QDs fluorescent marker for biomedical research is a new method. In addition, the bacterial count was one of the most important indexes in food hygiene, environmental monitoring and medical diagnosis. Based on the excellent luminescence properties of QDs, development of QDs-based fluorescence measurement method is foundation for detection bacterial count of the pathogenic Escherichia coli. The new type water-soluble, low toxicity of manganese doped quantum dots was prepared by choosing the new materials which was as markers for cell imaging, what was the foundation of the application of cell imaging. The main results were as follows:(1) Preparation of CdTe-PAMAM dendrimer nanocomposites by forming covalent bonds method by crosslinking agent EDC, the nanocomposites were characterized by photoluminescence (PL) spectra and transmission electron microscopy (TEM) images. The CdTe-Dendrimer nanocomposites were as a bioprobe for live cell imaging, which will probably be an attractive probe in cellular imaging and bio-labeling.(2) Based on the excellent luminescence properties of QDs, development of QDs-based fluorescence measurement method is for labeling and detectiing the pathogenic Escherichia coli. Influences of some factors on covalently coupled with target bacteria were investigated, including:The effects of reaction time, volume of CdTe QDs and so on. Development of QDs-based fluorescence measurement method is was one of the most important indexes in food hygiene, environmental monitoring and medical diagnosis(3) Low cytotoxicity Mn2+-doped ZnSe quantum dots (Mn:ZnSe d-dots) were synthesized successfully by a nucleation-doping method in aqueous solution with 3-Mercaptopropionic acid as the stabilizer and sodium selenite as the Se source for the first time in contrast to the use of oxygen-sensitive NaHSe or H2Se as Se source. The biological application of luminescent Mn:ZnSe d-dots to PK 15 cell imaging was also illustrated, which showed excellent biocompatibility and low cytotoxicity, implying their potential as a new generation of fluorescent labels for biological assays, tissues, and even in vivo investigations.In this paper, CdTe QDs covalently coupled with target bacteria were investigated. However, the detection of bacterial count of the pathogenic Escherichia coli needs to be further exploited. In addition, the optimum reaction conditions on synthesis Mn:ZnSe d-dots were decided by discussing the factors effecting the reaction. Therefore, we should do further research on it in future.