Hyaluronic acid-grafted titanium dioxide nanoparticles for moisture-retentive and non-cytotoxic sunscreen creams

The escalating UV exposure has emerged as a significant threat to human health, manifesting in both acute and chronic health impairments. To mitigate these risks, a biosafety sunscreen cream was prepared for UV protection and moisturization. TiO₂ nanoparticles (NPs) were sequentially coated with Al(OH)₃ and chemically grafted with hyaluronic acid (HA) to produce TiO₂-g-HA NPs. The optimized TiO₂-g-HA_0.1 NPs achieved a grafting efficiency of 6.2 %, enhancing its sun protection factor (SPF) from 13.3 ± 1.4 (TiO₂ NPs) to 19.1 ± 0.7. In the contrast, the TiO₂-g-HA_0.1 NPs exhibited a low photocatalytic activity to avoid the generation of hydroxyl radicals in a sunscreen formation. The TiO₂-g-HA NPs under a state of aqueous slurries were then incorporated into a commercial sunscreen formulation. The TiO₂-g-HA_0.1 Cream demonstrated exceptional stability, retaining >95 % of its initial SPF (24.5 ± 0.3) after 10 heating-cooling cycles, with no phase separation observed. In addition, the TiO₂-g-HA_0.1 Cream sustained an enhanced moisturization performance (>80.0 % hydration retention under thermal and convective stress). Biocompatibility assessments on HaCaT keratinocytes revealed minimal cytotoxicity, with 88.5 ± 0.9 % cell viability for the TiO₂-g-HA_0.1 Cream. Moreover, in vitro penetration profiles were possessed with the BALB/c mouse skin, confirming most nanoparticles retained on the epidermal surface for the TiO₂-g-HA_0.1 Cream.