The Preparation Of Fluorescent Nanocomposites And Their Application To Fluorescence Analysis

The fluorescent nanocomposites have become an attractive area of analytical chemistry research in recent years, and it has been known that they can be used as fluorescence probes for various bioassays. Compared to conventional fluorescent dyes, the advantages of fluorescent nanoparticles mainly include their higher photostability and stronger fluorescence. The nanoparticles are assembled in core-shell architecture. This architecture leads to a variety of physical and chemical properties, such as high hydrophile, easy preparation, separation and surface modification. However, if there is no chemical force between dye molecules and silica matrix, the problem of dye leakage from silica nanoparticles still exists after dispersing in the aqueous solution. In this paper, the multifunctional nanocomposites without dye leakage are prepared in the silica nanoparticles matrix by chemical bonds, which are very uniform in diameter. A novel method of determining nitrite was established based on the fluorescent nanoparticles.This paper consists of four chapters:Chapter 1: The development and appilications of nanomaterials were reviewed in modern analytical chemistry. The new material showed the exellent researching foreground.Chapter 2: The fluorescent nanoparticles covalently doped with Rhodamine B (RB) were prepared via 3-aminopropyltriethoxysilane (APTES) in reverse microemulsion system(W/O), which avoided the dye leakage efficiently. The surface of fluorescent nanoparticles formed another thin silica shell with the functionalized amino groups by the cohydrolysis and polymerization of tetraethoxysilane (TEOS) and APTES.Chapter 3: A fluorimetric method using the nanoparticles was proposed for the determination of the nitrite. The method was based on the fluorescence quenching of RBS by the reaction product of nitrite and potassium iodide in acidic solution. Moreover this method was proved to be simple, rapid and economic.Chapter 4: This part viewed the preparation of multifunctional nanocomposites possessing magnetism and fluorescence. The magnetite nanoparticles were prepared by the chemical co-precipitation method. After silica surface modification, a layer of silica was further coated on the surface of the magnetic nanoparticles in the presence of RBS molecules. Then a novel material possessing magnetic response, fluorescence, and bioaffinity properties could be achievable. Furthermore, RB was covalently doped into the nanocomposites, which efficiently avoided the dye leakage.