A Facile One-Pot Preparation and Catalytic Application of Tunable Silica-Coated Aqueous Gold Nanoparticles

It is known that designer polymers can be used for the synthesis and stabilization of metallic nanoparticle systems, providing new, tailorable properties. In this work, we demonstrate the trifold utility of a designer polymer, trimethoxysilylpropyl-(polyethylenimine) (TMSP-PEI), providing reduction, stabilization, and protection in a single step. Our facile and unique synthesis affords gold nanoparticles with varying sizes and morphologies in a range of solvents without the need for additional reducing agents. The use of this substituted polymer was manipulated in terms of the metal-to-ligand ratio to induce changes in the nanoparticle nucleation and growth. Upon further experimental analysis, it was discovered that adjustments to not only the metal-ligand ratio but also the solvent environment produced nanoparticles with different shape and size distributions. In addition, the synthesized gold nanoparticles were investigated for their catalytic ability to reduce Eosin Y in the presence of sodium borohydride without degradation.