Biocompatible Organosilica Nanoparticles with Self-Encapsulated Phenyl Motifs for Effective UV Protection.

With increasing ozone depletion, ultraviolet (UV) exposure from sunlight has become a significant health risk. Although commercially available sun protectants provide reasonable protection, they have limitations in terms of safety and aesthetics. Here, we have developed biocompatible and biodegradable sunscreens by facile synthesis of organosilica nanoparticles (o-SNPs) with self-encapsulated phenyl motifs using phenylsilane precursors. The physical structure of o-SNPs is elaborately controlled such that they are large enough to reflect UVA but small enough to be imperceptible when applied on the skin. The chemically attached phenyl motifs to o-SNPs facilitate filtering UVB via their delocalized π-orbitals. The o-SNPs generate a negligible amount of reactive oxygen species under UV exposure. Ex vivo two-photon microscopy reveals that the o-SNPs tend to adhere to the outer layers of skin without further intradermal penetration, resulting in less skin irritation. In vivo UV protection tests confirmed the excellent sunscreen effect of o-SNPs compared with conventional organic and inorganic UV filters.