Synthesis and characterization of 3D dendritic gold nanostructures and their use as substrates for surface-enhanced raman scattering

Three-dimensional dendritic gold nanostructures (3D-DGNs) were prepared at room temperature through an aqueous/organic interfacial reaction of hydrogen tetrachloroaurate (HAuCl4, in aqueous phase) and 3,4-ethylenedioxythiophene (EDOT, in organic phase) without the use of any seeds, templates, surfactants, or stabilizers. SEM and TEM studies indicated that the 3D-DGNs compose of numerous nanowires with diameters around 30 nm and each wire brings a nanosheet head with thickness of 80 +/- 5 nm. The effects of reaction conditions including the concentrations of HAuCl4 and EDOT, the reaction temperature, and the organic solvents on the morphology of 3D-DGNs were systematically investigated and a possible mechanism for the formation of 3D-DGNs was proposed. The 3D-DGNs can be used as substrates for surface-enhanced Raman scattering (SERS). They exhibited much higher surface enhancement than those of conventional electrochemically roughed gold surfaces and gold nanorods when 4-mercaptopyridine (4MP) was used as a molecule probe. The enhancement factor of 3D-DGN substrate was measured to be (1.9 +/- 0.4) x 10(6), and the limit of detection (LOD) was determined to be lower than 1 x 10(-10) M.