Synthesis, Functionalization, and Bioconjugation of Monodisperse, Silica-Coated Gold Nanoparticles: Robust Bioprobes

Abstract

Herein, we report an efficient process for preparing monodisperse Au@SiO2 nanoparticles using homogeneous shaking and without the use of surface‐coupling silane agents or large stabilizers. The resulting pure‐silica surface of the Au@SiO2 nanoparticles is very important for straightforward surface functionalization with different functional groups via well‐established silica surface chemistry. Subsequent covalent bioconjugation of the aldehyde‐functionalized Au@SiO2 nanoparticles with various biomolecules is successfully employed to make robust nanoprobes for fast, colorimetric DNA and protein detection based on the sequence‐specific hybridization properties of DNA and the specific binding affinity between proteins, respectively.

Preparation of organic–ceramic–metal multihybrid particles and their organized assembly

“…It is known that during the preparation of gold nanoparticles, some of the citrate ions decompose to form acetone, dicarboxylic acid, itaconic acid and so on, which are adsorbed onto the surfaces of gold nanoparticles. [17][18][19] After subsequent treatment of freshly prepared gold nanoparticles with additional citrate ions, fresh citrate ions can replace decomposed citrate ion products effectively, which results in a high concentration of citrate ion on the gold surface. Silica coating was first initiated by adsorption of silanol groups onto the nanoparticle's surface, leading to formation of a silica layer.…”

“…12 To carry out silica coating on the surface of gold nanoparticles, a high concentration of citric acid was necessary. [17][18][19] Therefore, the prepared citrate ion-coated gold nanoparticles were treated once again with 1 mM sodium citrate solution. It is known that during the preparation of gold nanoparticles, some of the citrate ions decompose to form acetone, dicarboxylic acid, itaconic acid and so on, which are adsorbed onto the surfaces of gold nanoparticles.…”

Functional Inorganic Nanohybrids for Biomedical Diagnosis

“…This could facilitate hydrolysis/condensation of tetraethyl orthosilicate. For example, Han et al [54] synthesized the monodisperse silica-coated gold particles derived from the citratestabilized gold particles. The prepared citrate-reduced gold particles are low stable for silica coating in alcoholic media.…”

Toward Greener Nanosynthesis

“…Candidates for postsynthetic modifications are generally produced by direct synthesis (ω-functionalized particles created by Brust preparations) or sometimes ligand exchange methods (usually involving the introduction of a ligand bearing a reactive pendant functional group). Modification reactions include polymerizations, [213][214][215][216] coupling reactions, 40,48,[217][218][219][220][221] or transformation of an existing chemical moiety. 48,[222][223][224] In all cases, the success of such modifications relies not only on the nanoparticles' tolerance for various reaction conditions but also on the overall reactivity and steric environment presented by functional groups that are constrained through binding to a nanoparticle.…”