Using nanoparticles to encapsulate the ultraviolet (UV) filters found in sunscreen might prevent them from being absorbed by the skin — and could even improve their UV-blocking performance.

Some studies have shown that chemical UV filters have negative effects on cells when they penetrate skin. To stop this absorption, Mark Saltzman and his colleagues at Yale University in New Haven, Connecticut, coated a typical UV filter — padimate O — with nanoparticles that have sticky aldehyde groups on their surfaces. The coated UV filters stuck to the skin of mice and pigs even when exposed to water, and the nanoparticles prevented the filters from penetrating the skin.

Sunblock that used these nanoparticles and contained only 5% of the amount of UV filters found in conventional sunblock absorbed the same level of UV radiation.

Nature Mater. http://dx.doi.org/10.1038/nmat4422 (2015)