Synthesis and Characterization of Gold−Silica Nanoparticles Incorporating a Mercaptosilane Core-Shell Interface

The first synthesis and characterization of gold−silica core−shell nanoparticles with a mercaptosilane interface between the core and shell is reported. These nanoparticles exploit the strong interaction between thiols and gold to create a well-defined interface of functional group organization between core and shell. This requires the synthesis of a mercaptosilane monolayer on the colloidal gold surface, which is accomplished indirectly using 1 as a protected precursor to 3-mercaptopropyltriethoxysilane. 1 binds to gold, undergoes sol−gel hydrolysis and condensation, and subsequently deprotects to a thiol via gold-catalyzed thioester hydrolysis. This process results in a monolayer of condensed mercaptosilane on the nanoparticle surface without inducing colloidal instability, which was observed upon direct mercaptosilane addition at the same surface coverage. Similar results were obtained for the previously reported thioester 2, which also binds to gold and deprotects in the bound state, as does 1, but la...