Single Gold Nanoparticles Encapsulated in Monodispersed Regular Spheres of Mesostructured Silica Produced by Pseudomorphic Transformation

Monodispersed, uniform, gold encapsulated−mesoporous silica nanocomposites of 100−350 nm diameter with a centered metal core at about 15 or 30 nm and high gold occupancy are prepared by pseudomorphic transformation of preformed gold−silica nanospheres. The characterization by X-ray powder diffraction, transmission electron microscopy, 29Si and 13C magic angle spinning NMR, and N2 adsorption isotherms indicates that these materials present the same morphology and particle size distribution of the parent amorphous silica but with an ordered mesoporous shell of complex wormhole-like pore structure and specific surface area of about 1000 m2 g-1. This method is particularly advantageous for both stabilizing gold nanoparticles and tailoring structural and textural parameters of the outer shell, thus, offering an exceptional support for particle functionalization.