Synthesis, Surface Modification, and Applications ofNanomaterials: Gold and Titanium Dioxide
| Autor: | Kun-Hong Li, 李昆鴻 |
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| Rok vydání: | 2008 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 96 With the growing advances in nanotechnology, a number of interesting related researches have been demonstrated. In this thesis, we mainly focus on the preparation of different kinds of nanomaterials including gold, silver, titanium dioxide, and on their applications to the analysis of aminothiols and polyphenolic compounds. In addition, capillary electrophoresis (CE) in conjunction with laser-induced fluorescence (LIF) has been conducted to study the interactions of DNA with Hg2+. We briefly describe preparation, physical and chemical properties of nanomaterials as well as introduce related techniques used in this thesis in Chapter 1. In Chapter 2, the interactions between a variety of thiols and Nile Red-adsorbed gold nanoparticles (NR-Au NPs) by monitoring the fluorescence changes of NR-Au NPs solutions are described. Using the Langmuir isotherm model, the displacement rate constants of the NR product from the Au NP surface are estimated. Our results reveal that steric effects and the charge density of the thiols both play important roles in determining the interactions with NR-Au NPs. The interactions are also dependent on the size of NR-Au NPs. Furthermore, the catalytic characteristics of Au NPs have also been proposed through the formation of an NR product from NR upon the Au NP surface. In Chapter 3, we demonstrate the preparation of Au and Ag nanomaterials from their corresponding colloidal seeds on glass substrates via a seed-mediated growth method. By carefully controlling the concentrations of Au and Ag nanoparticle seeds, different sizes and shapes of Au and Ag nanomaterials with narrow size distribution, higher yields (27% and 54%), and larger sizes (1.36 and 5.21 μm) can be prepared. Through dark-field microscopy (DFM) and SEM measurements, the thus-prepared nanomaterials were easily and rapidly characterized. From the scattering spectra of single Au and Ag nanomaterials, we obtaibned more detailed information about their morphologies. Combining our synthetic method with DFM system, the high-throughput preparation and characterization of differently sized and shaped Au nanomaterilas on a glass substrate can be achieved. We discuss use of titanium dioxide nanoparticles (TiO2 NPs) as selective probes and matrices for the determination of catechins through surface-assisted laser desorption/ionization mass spectrometry (SALDI-MS) in Chapter 4. Due to the high specificity of TiO2 NPs towards enediol-containing compounds as well as their strong absorption characteristics through efficient energy transfer, TiO2 NPs serve as affinity probes and as effective LDI matrices for the SALDI-MS determination of catechins. This method has been validated in the analysis of catechins, ascorbic acid and theanine in tea samples, showing its great potential for applications in life sciences. In Chapter 5, we discuss a simple and fast CE-LIF method for separation of short ssDNA fragments in the presence of Hg2+. Through the specific interaction of Hg2+ ions with thymine-thymine (T-T) base pairs of the DNAs, four ssDNA, including T33, C5T28, T5C5T23, and T15C5T13 were successfully separated by CE using poly(ethyleneoxide) (PEO) solutions. The separation of the four DNA fragments were completed within 20 min, with the relative standard deviation values all less than 2.5%. The Hg(II)-induced changes in conformation and charge density in the DNA are responsible for their changes in mobility during separation. Our reasoning is further supported by the fluorescence and ellipticity spectra. |
| Databáze: | Networked Digital Library of Theses & Dissertations |
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