How much sun is too much for surface oxygen vacancy rich-CeO2(0.3)/ZnO(0.7)@β-cyclodextrin quantum dots composites as smart sunscreen active ingredients: broadband UV shielding, cascade antioxidant, and biosafe

Ozone depletion has augmented photo-aging and sunburn caused by over-exposure to ultraviolet radiation (UVR). Widely used conventional sunscreens consisting of nanostructured inorganic UV filters – ZnO and TiO2, are potentially phototoxic and cause UV-induced DNA damage. This has led to new design considerations for active ingredients, emphasizing low cost, safety, and multi-functionality. In this study, broad-spectrum UV attenuation (250 nm-400 nm) and long-lasting photostability (> 5 h) are achieved in β-cyclodextrin functionalized, oxygen vacancy rich-ZnO/CeO2 quantum dots composites (VO●-CeO2(x)/ZnO(1-x)@β-CD QDs composite). The kinetically-driven synthesis exacerbates surface VO● concentration, modulating the band gap and facilitating enhanced molar absorptivity through photogenerated electron-hole separation. Additionally, surface VO● confers the nanocomposites with a self-cascading antioxidant effect, notably scavenging 62.8% of ●OH radicals. Endogenous O2 generation from H2O2 scavenging accelerated by Ce3+/Ce4+ couple benefits skin revitalization. The nanocomposites demonstrate remarkable cell viability (≥90%) and efficacy in alleviating sunburn, ageing, and ROS-induced skin ailments. Incorporating VO●-CeO2(0.3)/ZnO(0.7)@β-CD QDs composites as active ingredients in commercial sunscreens unveiled a substantial enhancement in the overall efficacy of sun protection. Thus, it is envisioned that VO●-CeO2(x)/ZnO(1-x)@β-CD QDs composites hold promise for developing newer, safe, efficacious, and economical sunscreen formulations, contributing to sustainable development goals.