Colloidal gold nanoparticles protected by water-soluble homopolymers and random copolymers

Stable gold colloids were prepared by the in situ reduction of tetrachloroauric acid (HAuCl4) in the presence of protective polymers. Several water-soluble polymers and random copolymers have been investigated for their ability to stabilize such gold colloids. UV-vis spectroscopy was used to follow the in situ reductions and to characterize the resulting gold colloids. The particle sizes and their size distributions were determined by transmission electron microscopy and found to be in the nanometer size range. The most stable colloids were obtained for polymers possessing hydrophobic backbones and for side groups that allow good interactions with the gold precursor ions. (C) 1997 Elsevier Science Ltd.