The Preparation Of CdTe@SiO₂ Core-shell Nanoparticles And The Study Of Porphyrin Reagent For Mo Determination

Nanomaterials were developed in 1980s, they showed unique and excellent performance because of their structures. The American Society of Materials commended them as"the most promising materials in 21st century". At present, they have been widely used in many fields, such as semiconductor chips, cancer diagnosis, new optical materials, biological molecules tracking and so on. The basic knowledge, characteristics, synthesis route and application fields of quantum dots (QDs), dye-doped nanoparticles and porphyrin are reviewed in chapter 1 of this thesis.In the chapter 2, a new route for preparation of CdTe nanocrystals (NCs) doped silica fluorescent nanoparticles is presented. With the aqueous CdTe NCs as fluophores, the CdTe NCs doped silica fluorescent nanoparticles were prepared using reverse microemulsion method following the electrostatic attraction mechanism. Results showed that more than one CdTe NC could be doped in one silica nanoparticle and no other reagents were needed. So as-prepared CdTe NCs doped silica nanoparticles had much higher luminescence intensity. The silica shell could effectively block the diffusion of oxygen and enhanced the photostability of the CdTe@SiO₂ core-shell particles. It was reasonable to infer that the silica could also block the diffusion of Cd2+ ions released upon the photooxidation of CdTe NCs, and reduced the cytotoxicity of these NCs in biological applications. At the same time, CdTe NCs doped silica nanoparticles with two emission wavelength were also prepared by the same method. And silica with good biological compatibility is easily modified with–COOH,–NH2 and other active groups. It has laid the foundation of expanding the application fields of nanocrystals in biological analysis and biological labeling.In Chapter 3, a new determination method of trace amount of Mo based on fluorescence spectrometry with a novel water soluble 5,10,15,20-tetra-(3- sulfonic-4- hydroxyl-5- ethoxyl phenyl ) porphyrin is described. Through systematic studies of the influence factors of this method, the determination conditions were optimized. In the HAc-NH4Ac buffer with pH = 3.5, the mass concentration of Mo had a good linear relationship with fluorescence intensity at the range of 1μg·L-1～10000μg·L-1. Mo in a practical sample was determined using the newly developed method and a comparable result with ICP spectrometry was obtained. This method is simple, sensitive, accurate and good for trace amount of Mo determination.