Synthesis, Assembly, and Biofunctionalization of Silica‐Coated Gold Nanorods for Colorimetric Biosensing

Abstract

Abstract An efficient silica coating process using an improved Stöber method has been used to prepare silica‐coated gold nanorods (Au rod @SiO 2 ). The resulting pure and clean silica surface of the gold nanorods (GNRs) is important for the facile self‐assembly of Au rod @SiO 2 films on poly(4‐vinylpyridine) (PVP) modified quartz substrates and offers versatile functional groups, such as the amino group, for the immobilization of biomolecules by well‐established silica surface modification protocols. The subsequent covalent bioconjugation of amino‐functionalized Au rod @SiO 2 films with goat anti‐human‐immunoglobulin G (anti‐h‐IgG) is successfully employed for the colorimetric detection of h‐IgG in a model reaction based on the specific binding affinity between the proteins. Significantly, the protein‐recognition event on the Au rod @SiO 2 films can not only be monitored by changes in the absorption of light, but is also observable by the naked eye.