(33a) Nanocomposites Of Inorganic Oxide Coated Gold Nanorods

Combining rod-shaped metallic nanoparticles such as gold nanorods (GNR) with inorganic oxides can be used to tailor the functional properties of the composite nanomaterial. For example, a dielectric SiO2 coating allows one to use traditional means for immobilizing biomolecules on the oxide and exploit the optical absorbance of the GNR for biosensing. Coating GNRs with a semiconducting oxide such as titanium dioxide (TiO2) can have uses in catalysis and a material such as iron oxide (Fe3O4) can be used in magnetic devices. In this presentation, we will discuss our research on fabricating and characterizing these nanocomposites. Specifically, we will discuss strategies that facilitate coating of inorganic oxides by first modifying GNRs with various polyelectrolytes by a layer-by-layer (LBL) technique. The polyelectrolyte layers stabilize the GNRs during re-dispersion in an organic solvent and allow partial shielding of the surface charge of the gold nanorods. Subsequently, techniques such as hydrolysis of tetraethyl orthosilicate or titanium(IV) isopropoxide can be used to coat the GNR. The presentation will focus on the synthesis of GNRs, the LBL polyelectrolyte coating technique, and the controlled coating of various inorganic oxides. Supporting characterization of the composites using UV spectroscopy, TEM and dynamic light scattering (DLS) will also be presented.