One-Dimensional Silica Nanostructures and Metal-Silica Nanocomposites: Fabrication, Characterization, and Applications

Among Si-based nanostructures, silica nanowires are gaining a great scientific and technological interest due to their potential applications such as new electronic devices, biosensors, and nanoscale optical devices. Furthermore, their chemical and physical properties, and so their performances in devices, can be enhanced if embedded or decorated on surface by metal nanoparticles (NPs) due to local plasmonic effects. In fact, properties such as surface-enhanced Raman spectroscopy (SERS) and optical wave guiding of the silica nanowires gain enormous benefit from the presence of the metal NPs. In particular, SERS effects in metal NPs/silica nanowires are extremely promising for diagnostics with rapid screening. Examples include identification of cancer malignancies and classification in oncology research and monitoring of drug recipient interaction in pharmaceuticals. The majority of single-molecule detection studies have utilized aggregates of metal NPs, which are particularly likely to form hot spots where Raman scattering is even more strongly enhanced due to electromagnetic coupling between NPs, and the coupling with silica nano wires leads to a further improvement of the light interaction due to the waveguide properties of the nanowires. Despite the importance of the one-dimensional metal/silica nanocomposite systems, a key question toward their device applications concerns the development of simple, low-cost, and versatile methodologies for their mass production directly on surface and for the wide-range control of their structural characteristics. So, in this chapter, we review, first of all, the most promising fabrication methods of one-dimensional.