| As a special type of semiconductor material, quantum dots have its unique properties, such as quantum size effect, surface effect, the quantum confined effect and quantum tunnel effect. We can obtain quantum dots with different size and shape by controlling the reaction time, temperature, pH, ligand, and so on. Compared with the traditional organic fluorescent dyes, quantum dots have narrow and continuous absorption spectrum, symmetrical fluorescence peak, adjusted fluorescence emission, stable optical performance, high fluorescence quantum yield and strong ability to resist photobleaching, etc.. Especially the quantum dots prepared in aqueous solution have the advantages of a good biological compatibility and easy surface functionalization, etc.. Owing to its unique optical properties, quantum dots have been used in the fields of immune analysis, biomedical imaging, chemical and biological sensing, and other fields.In view of the excellent optical performance of the quantum dots, in recent years, the fluorescence spectrum coding technology based on the quantum dots has also been caught high attention of the height of the relevant scientific research personnel. Usually, the encoding fluorescent nanoparticles are made up of fluorescence elements and micro/nano carrier. Organic fluorescent molecule, fluorescence metal complexes and quantum dots are the most typical three kinds of code elements. Because of its unique optical properties, quantum dots has gradually replaced the traditional fluorescent metal complexes and organic fluorescent molecul and has become an emerging element of fluorescent coding. It can be seen that quantum dots has attracting widespread attention.The commonly used code element carriers are polystyrene particle, silica nanoparticles and polymer particles. With the continuous development of nanotechnology, the silica nanoparticles with the advantages of easy preparation, separation, surface modification, as well as the good hydrophilicity and biocompatibility has been attracted more and more attention of researchers. In recent years, many domestic and foreign project team has assembled all kinds of fluorescent quantum dots, organic fluorescent dyes and metal complexes to the interior or surface of the silica and polystyrene particle in a controlled manner. Moreover, they also has studied the formation mechanism and the structure of particles. Thus is of great importance to he preparation and application of encoding fluorescent nanoparticles.On the basis of relevant theories, this paper mainly studied the preparation of composite (SiO2-CdTe QDs)/SiO2encoding fluorescent nanoparticles, the synthhesis of MSA-CdSe quantum dots and the preparation of core/shell CdTe/ZnO@SiO2composite materials. Specific experiment includes the following three parts:(1) Firstly, we prepared SiO2nanoparticles of surface amination with the Stober method, then respectively assembled on its surface with green and red fluorescence CdTe QDs on the surface of the silica nanoparticles by using the the strong covalent interaction between the carboxyl groups of MPA-CdTe QDs and amino groups, and finally coated SiO2-CdTe QDs nanoparticles with SiO2and informed composite (SiO2-CdTe QDs)/SiO2coding fluorescent nanoparticles in order to increase its chemical and optical stability. And we also preliminary discussed the interact between the composite (SiO2-CdTe QDs)/SiO2encoding fluorescent nanoparticles and hemoglobin.(2) In order to prepare CdSe quantum dots with high fluorescence quantum yield in water phase, we choosed mercaptosuccinic acid (MSA) as stabilizer, sodium selenite (Na2SeO3) as a source of selenium and the borate-citrate acid as buffering solution, and prepared high-quality CdSe nanocrystals(NCs) under open-air condition. Furthermore, we discussed the influence factors about molar ratio of reactant precursors, reaction time, temperature and pH of precursor. The prepared MSA-CdSe is with high fluorescence quantum yield, good dispersion, uniform particle size distribution and good hydrophilic. In addition, we specifically discussed the interaction mechanism between the MSA-CdSe quantum dots and hemoglobin.(3) After successfully preparing the CdSe quantum dots with high fluorescence quantum dots, we firstly synthesised the ZnO nanorods with the properties of colloidal, mono dispersity and single exciton emission through the reaction between zinc acetate and potassium hydroxide in methanol solution, then encapsulated ZnO nanorods and CdSe quantum dots with SiO2as package reagent, and became an common nano structure, forming tunable dual emission of water-soluble CdSe/ZnO@SiO2core/shell nano composite materials,... |
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