Controlled Synthesis Of Composite Silica Nanoparticles And The Study Of Its Fluorescence Property

In recent years, the composite fluorescent silica nanoparticles have attracting more attentions and have promising applications in the biological and medical field. They possess the advantages of both dyes and nanoparticles through their combination. The silica sphere can prevent the dye to be influenced by external environment. In addition, it also promotes the fluorescent efficiency, stability, biocompatibility, and lowers the toxicity. As a result, the composite fluorescent silica nanoparticles can be directly connected with biological cells and molecules, overcoming the disadvantages of traditional organic dye, such as, fluorescence quenching and poor stability.The silica nanoparticles have been gradually applied to build composite functional fluorescence materials due to their advantages of nanometer size, large specific surface area, adjustable particle size, stable structure, excellent bio-affinity and non-toxicity. It has great prospects for development of new biological probes and plays an important role in biological imaging, biological detection, drug loading, disease diagnosis, biological sensing and so on. Through analyzing and detecting the active substances inside the life system at the nanoscale, chemical and biological information of the life processes can be obtained at the cellular and molecular level, which is very significant to understand the relationship between the structure and function of biological molecules, and explain the mechanism of their vital movement.This thesis chose the fluorescein isothiocyanate (FITC) as fluorescent dyes to prepare composite fluorescent silica nanoparticles with high sensitivity, stablility and good monodispersity, which can be used as biological analysis. The products were analyzed and characterized by TEM, SEM, DLS, UV-Vis spectroscopy, Fluorescence spectroscopy and Infrared spectroscopy. As a result, the synthesis mechanism and influence factors were investigated. Furthermore, the fluorescence property was also measured and optimized. The contents of this thesis include:(1) The methods of inverse micro-emulsion, Stober method, soft temple method are chose respectively to prepare the silica nanoparticles with uniform and suitable size. We discussed the synthesis mechanism and influence factors for size, morphology, dispersity and uniformity. Consequently, the reaction conditions were optimized in our work. We achieved the goal of controlled synthesis and obtained a biological substrate material.(2) We selected the non-toxic dye, FITC as fluorescent dyes to prepare nano biological fluorescent probe. Then the fluorescent property was measured by Fluorescence spectroscopy.(3) In order to solve the problem of low doping efficiency, we used FITC to prepare the dye-precursor which coupled with a silane coupling agent,3-aminopropyl-trimethoxysilane (APTES), designed the dye leakage experiment and studied the fluorescence intensity and stabliity of the composite nanoparticles. Compared with the traditional physical adsorption method, the disadvantages of low doping efficiency, dye leakage and poor stablity were solved. Besides, we also optimized the fluorescence property of these composite fluorescent silica nanoparticles.