Formation and Adsorption of Clusters of Gold Nanoparticles onto Functionalized Silica Nanoparticle Surfaces

This paper reports a systematic investigation of the growth and attachment of small gold nanoparticles to the functionalized surfaces of larger silica nanoparticles. Dilution of the gold nanoparticles in mixtures of water and ethanol led to the self-assembly of gold nanoparticles in aggregates of regular size and shape attached to the surfaces of the silica nanoparticles. Functionalization of the surfaces of silica nanoparticles with different terminal groups had a profound influence over the coverage of gold nanoparticles and clusters. While the hydrophilic functional groups NH2 and SH bound the gold nanoparticles, hydrophobic functional groups such as CH3 and PPh2 did not. The coverage of the gold nanoparticles and clusters on the surfaces of the silica nanoparticles was evaluated using transmission electron microscopy.