The application of nanoparticles in the processes of making commercial products has increased in recent years due to their unique physical and chemical properties. Few such commercially available nanoparticles are TiO2, ZnO and SiO2.

Fabrication of oxide nanoparticles
The most widespread route to fabrication of metal oxide nanoparticles involves the “bottom-up” approach involving the precipitation from aqueous solution from metal salts. Organo metallic species can also be used, but due to their cost and the difficulty in manipulating these compounds, they are used less frequently. An alternative “top-down” approach has been demonstrated for aluminum and iron oxide nanoparticles; however, it is possible that this methodology could be extended to other oxides.
Compared to the synthesis of metallic and non-oxide nanoparticles, the approaches used in the fabrication of oxide nanoparticles are less elaborate and there are less defined general strategies for the achievement of mono sized distribution. Although all the fundamental considerations, including a burst of homogeneous nucleation and diffusion controlled subsequent growth, are applicable to the oxide systems, the practical approaches vary noticeably from system to system. Reaction and growth in the formation of oxide nanoparticles are more difficult to manipulate, since oxides are generally more stable thermally and chemically than most semiconductors and metals. For example, Ostwald ripening is applied in the synthesis of oxide nanoparticles to reduce size distribution; the results may be less effective than in other materials. The most studied and best established example of oxide colloidal is silica colloids though various oxide nanoparticles have been studied. Commonly oxide particles in colloidal dispersions are synthesized by sol-gel processing. Sol-gel processing is also commonly used in the fabrication.
With increasing amount of commercial nanoparticles released into nature, their fate and effects on the ecosystem and human health are of growing concern.