Synthesis And Study Of Quantum Dots For Bology Tag

As a new type of fluorescence materials, quantum dots (QDs) have many advantages over the traditional materials. The best merit of QDs is that the color of QDs can be adjusted. In comparison with the organic fluorescent dye, QDs fabricated by the same semiconductor can even emit white light besides different color homogeneous light through changing their size. Furthermore, QDs have many characteristics such as broad excitation spectrum, narrow/symmetric emission spectrum and high stability. Therefore, QDs have shown tremendous potential in biochemistry, cell biology and bology tag are being developed in years. Thereinto, ZnS QDs with the properties of infrared-lucency, fluorescence, phosphorescence and so on have been intensively studied, which was owed to their potential applications in photo-sensor, display panel and fluorescent-based labeling. So the preparation of ZnS QDs with quantum confinement effect, narrow size distributing and appropriate surface shape is very important.In this thesis we have finished the work as the following: 1) C2H5NS (TAA), Zn(CH₃COO)₂·2H₂O, CH₃COOH and CH₃COCH₃ were used as starting materials to prepare ZnS QDs with the average size of 3nm. And then, the effects of preparation parameters (such as reaction temperature, growth time, pH value of Zn(CH₃COO)₂·2H₂O solution and the concentration of TAA) on the size and emission intensity of ZnS QDs were discussed, and then the best condition of preparing ZnS QDs was obtained. The size, the cystal structure and luminescent properties of ZnS QDs were characterized by transmission electronic microscope (TEM), X-ray diffraction (XRD) and fluorescence spectrum. The result showed that the product had excellent crystal structure, good specific dispersivity, uniform size and good fluorescence characteristic. This method is safe, cheap, repeatable and convenient to operating but not need special facilities. 2) We synthesized ZnS: Mg(Ba) QDs. The result indicated that ZnS:Mg QDs were a potential shortwave photoelectricity apparatus, and doping of Ba²⁺ decreased the emission intensity of ZnS QDs. 3) We prepared ZnSe/ZnS QDs by sol-gel method and studied their luminescent properties . The result showed that the emission intensity of ZnSe/ZnS QDs was weaker than ZnSe QDs. After dealing with anneal, the emission intensity of ZnSe/ZnS QDs was increase but the intensity was still weaker than ZnSe QDs. 4) The result of biology experiment indicated that ZnS QDs could be used as fluorescence probes in vivo. However, its inertia and permanent toxicity in vivo were needed to be solved.