gold nanoparticles could be easily prepared by reduction of Au(III) salts in the presence of a good ligand. Organic thiols are particularly good at coating Au nanoparticles, as they adsorb to the gold surface very strongly and are compatible with a large variety of functional groups.
Phytochemicals found in various plant sources have been utilized as a means of developing a more economical and environmentally friendly synthetic pathway in the formation of gold nanoparticles.