Preparation And Surface Modification Of Gold Anomaterials

In this work, several series of gold nanospheres and nanowires were prepared and their modification was investigated by poly(ethylene glycol) thiol (PEG-SH) and poly(N-isopropyl acrylamide) thiol (PNIPAM-SH), as well as the application of gold nanospheres as printing ink and the interaction of gold nanowires with chromophores. The main contents and results included the following points:1. In the citrate-reduction method when adding chloroauric acid into sodium citrate solution the uniform gold nanospheres were obtained with a diameter of sub-10 nm in a large molar ratio range of citrate to Au precursor, while adding adding sodium citrate into chloroauric acid aolution more larger gold nanospheres, which had a relatively uniform diameter of 13.8-18.2 nm as the molar ratio of citrate to Au precursor of 4-6. Based on the seed growth method of large gold nanospheres, an automatic injection pump could simplify the operation and benefit for a large amount producing.2. Considering the polymeric special stabilization, the stability of gold nanospheres were largely enhanced when they were modified by PEG-SH and PNIPAM-SH. Small gold nanospheres modified by PEG-SH could keep the monodispersity after centrifugation, but large gold spheres could not due to its low molecular weight. Small gold nanospheres modified by PNIPAM-SH showed good stability. The polymer modified gold nanospheres could be concentrated into nano-metal inks for printing.3. In the preparation of gold nanowires by surfactant-assisted seed-growth method, the presence of HBr was found to benefit the produce of gold nanowires, in which the concentration of HBr and the quality of surfactant (CTAB) acted much importance. At a low HBr concentration gold nanowires were obtained with a uniform length and an aspect ratio of 10-15. However, at higher HBr concentration the gold nanowires showed larger average aspect ratio (20-70) but had a wide distribution in length.4. The modification of gold nanowires by PNIPAM-SH could enhance their stability due to the special stabilization, the precipitates of gold nanowires after modification could be easily redispersed by shaking. The modified gold nanowires did not show obvious influence to the photoluminance of fluorescein and Rhodamine B. The absence of metal surface enhanced fluorescence was ascribed to the failure in the control of the distance between nanowire surface and choromophores.