Gold Coating of Silver Nanoprisms

Core-shell Ag@Au nanoprisms are prepared through a surfactant-free seed-mediated approach by taking advantage of the anisotropic structure of silver nanoprisms as seeds. The gold coating on the silver nanoprism surface is achieved by using hydroxylamine as a mild reducing agent, and the final fully gold-coated prism structures are confirmed by microscopic and spectroscopic characterization. The resulting Ag@Au core-shell structure preserves the optical signatures of nanoprisms and offers versatile functionality and particularly better stability against oxidation than the bare silver nanoprism. The surface plasmon resonances of the core-shell Ag@Au nanoprisms can be tuned throughout the visible and near-IR range as a function of the Au shell thickness. Such tailorable optical features and surfactant-free gold shells have great potential applications in biosensing and bioimaging. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.