Abstract
Water-soluble gold (Au) nanoparticles were prepared using phase transfer method, and their dispersion properties were investigated. Using mercaptocarboxylic acids having various alkyl chain lengths as stabilizing agents, Au nanoparticles stably dispersed in aqueous solutions were obtained. The Au core size of the nanoparticles decreased with increasing the alkyl chain length of mercaptocarboxylic acid. From dynamic light scattering measurement the dispersion size of Au nanoparticles coated with 6-mercaptohexanoic acid was almost constant with the solution pH while that of 15-mercaptopentadecanoic-acid-coated ones increased with decreasing of the solution pH and they completely precipitated at pH 5. These indicate that the dispersion behavior of the Au nanoparticles depends on the alkyl chain length of stabilizing agent, and is sensitive to the solution pH in the case of the particles with longer chains.
