Photoprotection in the era of nanotechnology.

Commercial sunscreen based on nano-sized titanium dioxide (TiO(2)) and zinc oxide (ZnO) delivers superior UV protection and reduces whitening on skin compared to the older generations of inorganic sunscreens. This review discusses the historical use of nano-sized TiO(2) and ZnO in sunscreen and the relationship between UV attenuation and the primary particles, aggregates and agglomerates that make up these inorganic oxides. In addition we reviewed the recent safety concerns surrounding these materials, specifically, percutaneous penetration of TiO(2) and ZnO nanoparticles through human skin and their potential to cause phototoxicity.

UV absorption and scattering properties of inorganic-based sunscreens.

This article first introduces the concepts that underlie the calculations of scattering and absorption of light by small particles. Results of Mie theory calculations of light scattering and light absorption by 20, 50 and 100 nm TiO₂ and ZnO particles are then presented. As the attenuation, or extinction, by these particles is the sum of the scattering and absorption, the attenuation can then be calculated for wavelengths over the UVA and UVB region.

Characterization of TiO2 nanoparticles surface modified with aluminum stearate.

This paper uses measurements of adsorption and vibrational spectra (DRIFTS, ATR, and Raman) to characterize TiO2 (rutile) nanoparticles that have been surface treated with aluminum and stearate, "aluminum stearate". From these measurements, we have developed a model of titania particles covered by patches of "alumina". Vibrational spectra, particularly the spectra of the carboxylate headgroups, show that the stearate then adsorbs on both the titania and the alumina.