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, Si-29 and C-13 magic angle spinning NMR, and N-2 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 m(2) 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.