Biornimetic coating of gold nanoparticles with ultrathin silica layers

Abstract

Encapsulation of nanoparticles has attracted a great attention as a method for stabilizin g nanoparticles and subsequently applying them to various areas of technologies. Especially, the encapsulation of nanoparticles with silica shells has proven advantageous for applications to (nano)biotechnology with the well-established silica chemistry. However, current chemical approaches to the formation of silica shells generally require harsh conditions. In contrast, biological processes are capable of generating silica nano/microstructures under ambient conditions. In this work, we formed ultrathin (similar to 1.5 nm) silica shell-coated nanomaterials by mimicking the biological processes. The procedure consists of simple two steps: immobilization of a thiol-terminated imidazolium ion onto gold nanoparticles (AuNPs) and biomimetic polycondensation of silicic acids. The resulting AuNP/silica hybrids were characterized by Fourier-transform infrared spectroscopy, transmission electron microscopy, and UV-vis spectroscopy. (c) 2007 Elsevier B.V. All rights reserved.