Nanotechnology-based sunscreens—a review

The daily use of sun protection is essential to prevent the damaging effect of incident solar ultraviolet (UV) radiation. Sunscreens are cosmetic products containing UV filters as active compounds, which are responsible for the absorption and/or reflection of UV radiation that might otherwise reach the skin surface. Sunscreen formulation has undergone a major technological transformation over the recent past, resulting in improved sunscreen efficiency and safety. In this context, nanosystems have emerged as suitable carriers of UV filters, originating from the so-called nanosunscreens. The aim of the present review is to provide a conceptual framework based on several nanosystems at the forefront of these advances, including nanoemulsions, liposomes and ultradeformable vesicles (transfersomes, ethosomes, and transethosomes), solid lipid nanoparticles, nanostructured lipid carriers, polymeric nanoparticles, mesoporous silica nanoparticles, nanocrystals, and SunSpheres. Moreover, the beneficial effects these nanosystems impart to typical formulations are described. Finally, the potential impacts of these nanosystems on human health are discussed, and regulatory approaches by administrations around the globe are reviewed.