Silica nanoparticles-walled microcapsules

The process of fabricating silica colloidosomes through sol-gel process, was described. The process provides a way to construct new microstructures with nanosized building-blocks and generate microcapsules with controllable permeability. The silica nanoparticles were formed by hydrolyzing silica in aqueous media under the catalysis of dilute acid and introducing ammonia for condensation of sol. The optical microscope image of the microcapsule by transmission light method shows that silica microcapsules are spherical and hollow. The SEM image of a collapsed microcapsule and the corresponding section of its wall revels that the thickness of the wall is 0.5 μm and the diameter of the microcapsule is 70 μm. The enlarged section of the wall selected from the microcapsule indicates that the walls are composed of close-packed layers of nanoparticles. The apertures between these silica nanoparticles provide channels for the delivery and release of active core ingredients.