Monofunctional group-modified gold nanoparticles from solid phase synthesis approach: Solid support and experimental condition effect

We herein report a systematic study of solid-phase place exchange reactions for the synthesis of gold nanoparticles with a single surface functional group. This approach is based on a "catch and release" mechanism to control the number of functional groups attached to the nanoparticle surface. Bifunctional thiol ligands with a carboxylic end group were first immobilized on a solid polymer support in a controlled density. The density was low enough that neighboring thiol ligands were far apart from each other. When the modified polymer support was incubated in a butanethiol-protected nanoparticle solution, a one-to-one place exchange reaction took place between the polymer-bound thiol ligands and the nanoparticles. After cleaving off from the solid support, nanoparticles with a single carboxylic group were obtained as the major product. By varying the solid supports and reaction conditions, we succeeded to obtain monofunctional gold nanoparticles with enhanced yield and high purity.