Nonionic surfactant-assisted, seed-mediated growth of gold nanotoroids

Gold (Au) nanotoroids with ring-like structures and vacancies at their center are successfully synthesized through a seed-mediated method using nonionic Brij35 surfactant, which acted as a reducing, surface-stabilizing, and shape-directing agent. The relative amount of Au seed nanoparticles significantly affects the formation yield of Au nanotoroids and the morphologies of the resulting Au nanostructures. The possible formation mechanisms are discussed by analyzing time-resolved microscopy images and UV-Vis spectra.