Preparation, Property And Surface Modification Of The Luminescent Nano-composite Materials

Because of their many unique optical characteristics, high surface-to-volume ratio and other properties related to their nanometer dimension, nanoparticles have gained increasing attention in the fields such as bioassay and biological technology applications. After modified with functionalized groups, these nanoparticles with carefully adjusted compositions could be connected with biomolecules such as antibodies and proteins, forming the probes for biological experiments. These probes would be of high sensitivity and high selectivity to be applied in the domains of biology, pharmacy, diagnostics, etc. As a commonly used inorganic material, silica nanoparticles have several advantages over others: chemical inert, stable as colloidal, biocompatible and easy to modify. Fluorescent nanocomposites are now widely studied to develop their practical application as luminescent matrix in biological technology and applications. In the present dissertation, we investigated the preparation, property and surface modification of the fluorescent-silica nanocomposite materials for their biological applications. 1. Preparation and surface modification of the fluorescent silica nanocomposites in water-in-oil microemulsions. Water-in-oil microemulsions is a commonly used system to prepare monodisperse super small particles. Based on the traditional st?ber method of synthesizing silica particles, fluorescein isothiocyanate (FITC) molecules were doped into the network of the silica particles after the coupling of the FITC molecules with 3-aminopropyltriethoxysilane, and FITC-SiO2 composites with stable fluorescent property were prepared. In this way, we resolved the problem of dye leakage. This technique laid the foundations of the success to further modification and biological coupling of the silica particles. Amino-FITC-silica particles were prepared with amino groups on the surface by modifying the FITC-silica particles with 3-aminopropyltriethoxysilane. The Zeta potential experiments validated the existence of the amino group on the surface of amino-FITC-silica particles. Furthermore, we also studied the effect of the amount of the 3-aminopropyltriethoxysilane on the amount of the amino group on the surface of amino-FITC-silica. For the purpose of immunoassay, amino-FITC-silica particles were conjugated to monoclonal antibody. The fluorescent biological probes of amino-FITC-silica /IgGH were finally prepared. BSA was chosen to block the conjugates. The fluorescent biological probes were tested using the immunochromatographic strip assay. It indicated that the prepared fluorescent biological probes could be better blocked with BSA and exhibited high activity. These probes were quite suitable for the need of the rapid immunoassay. It laid reliable experimental foundation for future diagnostic applications. 2. Preparation and surface modification of the silica nanoparticles in ethanol. The procedure of preparing silica particles in ethanol is simple and the particles synthesized were uniform in size and the following separation and purification steps are also straightforward. In this dissertation, silica particles in...