The shape of titanium dioxide nanomaterials modulates their protection efficacy against ultraviolet light in human skin cells

Skin protection against ultraviolet (UV) radiation is necessary to reduce sunburn damage (erythema) and has been recognized as an important preventive measure against the development of cancer. Many sun-blocking pharmaceutical products are based on titanium dioxide nanomaterials (TiO 2 NMs) due to their UV barrier properties. This study aimed to assess if the UV protective efficiency of TiO 2 NMs depends on their shape. We prepared TiO 2 nanowires (TNW), TiO 2 nanotubes (TNT), and TiO 2 nanoplates (TNP) and tested their effects on human keratinocytes before and after UVB irradiation under in vitro exposure settings. The UVB radiation was applied at the dose equivalent to the UV component observed in one medial erythemal dose. The biological effects of TiO 2 NMs on nonirradiated and UVB-irradiated keratinocytes were observed by means of cell viability, genotoxicity, and inflammatory response. The obtained results clearly showed that the effects of TiO 2 NMs in vitro, either cytotoxic or protective, depend on their shape. These observations highlight the beneficial properties of nanomaterials that can improve the quality and efficacy of nano-enabled products only if the safe-by-design concept has been implemented during the innovation process.