RESUMO
We have developed a technology to incorporate micronized titanium dioxide (TiO(2)), together with antioxidants, in particles of a UV-visible transparent polymer gel. These particles are coated with silica to avoid clustering and the size of the micronized TiO(2) reduces the back scattering of white light. gel-trapped TiO(2) minimizes the oxidative stress exerted by UV radiation, increases the photo-stability of some accompanying ingredients, such as avobenzone. The size of the particles is in the micrometre range. This favors their permanence on the top of the stratum corneum. Gel-trapped TiO(2)-based sunscreens provide a larger SPF and two-fold larger UVA protection than equal-composition sunscreens that contain larger amounts of untrapped TiO(2).
RESUMO
Chemical grafting of anti-oxidant molecules with an additional hydrophobic polymer coating directly onto TiO(2) particle surfaces, using sonochemistry, is found to eliminate photocatalytic degradation enabling highly effective screening against UV radiation.