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Title: Surface modification and functionalization of silicon nanowires and their applications in biochemistry
Other Titles: Na mi gui xian de biao mian xiu shi yu gong neng hua ji qi zai sheng wu hua xue fang mian de ying yong
Authors: Chen, Weiwei (陳薇薇)
Department: Dept. of Physics and Materials Science
Degree: Doctor of Philosophy
Issue Date: 2006
Publisher: City University of Hong Kong
Subjects: Nanowires
Nanowires -- Surfaces
Notes: CityU Call Number: TK7874.85.C43 2005
Includes bibliographical references.
Thesis (Ph.D.)--City University of Hong Kong, 2006
viii, 140 leaves : ill. ; 30 cm.
Type: Thesis
Abstract: Semiconductor nanomaterials now become the intensive focus of research owing to their different properties compared with bulk materials and unique applications in physics and chemistry as well as fabrication of nanoscale devices. It is well accepted that one dimensional semiconducting nanomaterials provide a good system to investigate the dependence of electrical transport and chemical properties on dimensionality and size reduction. Because silicon is of great technological importance in microelectronics, silicon nanowires (SiNWs) have been a topic that has attracted great attention recently. Silicon nanowires (SiNWs) are of special interest also because they are expected to play an important role as their surface can be modified to act as both interconnects and functional units such as immobilizing matrixes in fabricating electronic, electrochemical devices with nanoscale dimensions. Obviously, the chemical properties of SiNW surfaces are crucial to their application in mesoscopic electronic devices in terms of their stabilities and transport properties, among many others. In this thesis, we investigated the surface properties of etched silicon nanowires by microattenuated total reflection (ATR)-FTIR spectroscopy. In view of the fact that little is known about the etching behavior of one dimensional silicon nanowires (SiNWs) as a function of the etchants as well as the concentration and pH of the etching solution, we have conducted a systematic study of the etching behavior of one dimensional SiNWs in various etching solutions and conditions. The results are compared with those of two dimensional Si wafers. After etching and modified with certain functional group of SiNWs, we used and compared three different surface-treated SiNWs as structural support for glucose biosensor and investigated the electrocatalytic performance of the resulting biosensors. We demonstrate that SiNW-based biosensors have good biocompatibility and exhibits fast response and high sensitivity to glucose, showing that SiNWs are good electrode materials as biosensors for glucose detection. The present method offers a general approach to using semiconductor nanowires as biosensors for sensitive, label-free, real-time detection of a wide range of chemical and biological species. Before it can be incorporated into new and existing biomedical devices, the toxicity of SiNWs needs to be thoroughly investigated. In our experiments, the tested SiNWs (As-Si, HF-Si and COOH-Si) exhibit quite different cytotoxicity to cells. Cytotoxicity of studied materials was observed at a wide range of concentration. The cytotoxicity was indicated by the Alamar Blue assay. The comparative toxicities of three types of SiNWs to cells are different, although they may or may not reflect in the real toxicological effects in vivo. These results suggest that the toxicology of these nanomaterials must be assessed before widespread public exposure that appropriate protective measures can be developed also human and environmental health risks of different SiNWs must be evaluated individually.
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