A previous method proposed for gold deposition on silica spheres (Kobayashi et al., 2005) was extended to uniform deposition of Au nanoparticles on submicron-sized polystyrene spheres. This method consisted of surface-modification and elecroless Au plating. The chemical agents examined for the surface-modification were sodium persulfate, 3- aminopropyltrimethoxysilane, polyelectrolytes and polyvinylpyrrolidone. The elecroless Au plating included three steps: (1) the adsorption of Sn 2+ ions took place on surface of silica particles, (2) Ag+ ions added were reduced and simultaneously adsorbed to the surface, while Sn2+ oxidized to Sn4+, and (3) Au+ ions added were reduced and deposited on the Ag surface. TEM observation revealed that Au nanoparticles with sizes of 8-25 nm were uniformly deposited on the polystyrene spheres that were modified with polyvinylpyrrolidone. The Au nanoparticle deposition was confirmed by UV-VIS absorption spectroscopy.
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