Synthesis, Characterization and Biological Applications of Inorganic Nanomaterials

This dissertation, "Synthesis, Characterization and Biological Applications of Inorganic Nanomaterials" by Rong, Chen, 陳嶸, was obtained from The University of Hong Kong (Pokfulam, Hong Kong) and is being sold pursuant to Creative Commons: Attribution 3.0 Hong Kong License. The content of this dissertation has not been altered in any way. We have altered the formatting in order to facilitate the ease of printing and reading of the dissertation. All rights not granted by the above license are retained by the author. Abstract: Abstract of thesis entitled SYNTHESIS, CHARACTERIZATION AND BIOLOGICAL APPLICATIONS OF INORGANIC NANOMATERIALS Submitted by Chen Rong for the degree of Doctor of Philosophy at The University of Hong Kong in March 2006 Nanomaterials, which are materials where at least one dimension is in the nanometer range (1 100 nm), exhibit properties and functions that are significantly different from those of the corresponding bulk materials. They have an extremely broad range of potential applications, especially in biological systems. The antimicrobial activities of silver nanoparticles against common and periodontal pathogens were investigated. Silver nanoparticles showed higher antimicrobial activities towards a selection of microorganisms than silver nitrate did under identical concentrations. This result, together with their low toxicity and ease of delivery, suggests that silver nanoparticles could be valuable antimicrobial agents suitable for sustained release and localized delivery in the treatment of wounds or periodontitis. Both atomic force microscopy and transmission electron microscopy data demonstrate that silver nanoparticles are bound easily, or subsequently uptake by the microorganisms effectively. Silver nanoparticles can also inhibit HIV-1 reverse transcriptase and HBV replication in vitro with low effective inhibitory concentration (in micromolar range). Silver nanoparticles exhibited low cytotoxicities towards Hut/CCR5 and normal PBMC cells. Their antimicrobial and anti-viral properties were retained upon conjugation with human serum albumin (HSA) and transferrin (hTF). A novel method for the preparation of gold nanoparticles from H[AuCl ] in Hepes buffer at room temperature is presented. Gold nanoparticles with different morphologies and sizes were obtained in the presence of surfactants. These gold nanoparticles can conjugate with HSA and hTF readily, and these proteins can also influence the formation of gold nanoparticles in Hepes buffer. The process of cellular uptake of transferrin- conjugated gold nanoparticles on the surfaces of live cells was visualized, and intracellular gold concentrations were measured. Internalization of the TF-coupled nanoparticles was mediated via the specific TF-receptor conjugation pathway. These observations provide invaluable information for guiding future improvements in the design and delivery of nano-drugs. Bismuth has well-characterized antimicrobial properties. Bi S nanorods, 2 3 (BiO) CO nanotubes and nanoparticles, Bi O nanotubes and nanoparticles were 2 3 2 3 synthesized and their anti-Helicobacter pylori properties were evaluated. Highly crystalline Bi S nanorods were prepared from bismuth citrate using a simple reflux 2 3 reaction (160 C). Bismuth citrate may play an important role in the synthesis by acting as both the bismuth precursor and a template. (n-hexadecyl)trimethylammonium bromide (CTAB) acts as a capping agent to prevent the aggregation of Bi S nanorods. (BiO) CO 2 3 2 3nanotubes were fabricated from bismuth citrate under moderate conditions whereas spherical (BiO) CO nanoparticles were synthesized by a water-in-oil (w/o) 2 3 microemulsion assisted with hydrothermal method. Importantly, these nanotubes and nanoparticles showed slightly higher antibacterial properties than the clinically used bismuth drug against H. pylori, a bacterium that causes peptic ulcers and ga