Date of Award
4-11-2011
Document Type
Dissertation
Degree Name
Doctor of Philosophy (PhD)
Department
Chemistry
First Advisor
Julia Xiaojun Zhao
Abstract
Dye-doped silica nanoparticles (DDSNs) are one of the most popular fluorescent nanomaterials in bioapplications. The first chapter of this dissertation provides an overview of the DDSNs including general fabrication methods, unique properties, and current challenges. In the following three chapters, this dissertation is focused on two challenging areas of DDSN studies. One is the fundamental properties of dye molecules in the DDSNs, and the other is the design of new multifunctional DDSNs for bioapplications. In the first area, the effect of silica nanomatrix on the properties of doped molecules was investigated. Two important molecular properties were covered including the reaction kinetics and the fluorescence quantum yield of the doped dye molecules. In the second area, a new bifunctional silica nanoparticle was developed and applied to photothermal therapy. The study of kinetics of encapsulated molecules in a nanoscale silica matrix was carried out using a model of the metalation of meso-tetra (4- N,N,N-trimethylanilinium) porphyrin tetrachloride (TTMAPP) with Cu(II). Various sizes of silica nanomatrixes were synthesized to investigate the effect of nanomatrix size on the kinetics of encapsulated molecules. The results demonstrated that the encapsulated molecules retained reactivity, but the reaction rate constant greatly decreased in the silica nanomatrix in comparison to free TTMAPP molecules in a bulk solution. Next, a dye-doped silica nanoparticle was employed as a model for the study of the nanomatrix effect on the fluorescence quantum yields of encapsulated dye molecules. Two types of dye molecules were selected based on their different responses to the surrounding media. Several major factors that affect fluorescence quantum yields in the nanomatrix were investigated, including aggregation of dye molecules, diffusion of atmospheric oxygen, dye concentration, and size of the nanomatrix. The results showed that the silica nanomatrix would have varied effects on the fluorescence quantum yields of the encapsulated dye molecules. Finally, a bifunctional silica-gold-silica sandwich nanoparticle was developed for biosensing and photothermal therapy. With laser irradiation, the nanoparticles showed a significant photothermal effect in the solution. This effect was applied to killing target cells in vitro. Overall, this dissertation covers both fundamental studies and applications of DDSNs.
Recommended Citation
Liang, Song, "Silica Nanomatrix Effect On The Properties Of Encapsulated Molecules And Silica-Metal Nanoparticles For Bioapplications" (2011). Theses and Dissertations. 8095.
https://commons.und.edu/theses/8095