In situ O2-releasing quantum dot composites with enhanced radical scavenging behaviour, biosafety, and broadband UV shielding applications

Understanding the defect-driven photophysics-surface chemistry interplay at the nanoscale further augments new design considerations for active ingredients for skin UV protection, emphasizing affordability, safety, and multi-functionality. Accelerating it, our study unravelled broad-spectrum UV attenuation (250 nm-400 nm) and long-lasting photostability (> 5 h) exhibited by in-house fabricated β-cyclodextrin functionalized, oxygen vacancy rich-CeO2/ZnO quantum dots composites (VO●-CeO2(x)/ZnO(1-x)@β-CD QD composites). A conceptually different strategy was pursued, involving artificially engineering surface VO● defects to modulate the band structure and enhance the molar absorptivity through photogenerated electron-hole separation. Unlike the conventional inorganic UV blockers, the QD composites harnessed their surface VO● to participate in a self-cascading antioxidant effect, scavenging 62.8% ●OH radicals. Results indicated that autocatalytic endogenous O2 generation from H2O2 scavenging accelerated by Ce3+/Ce4+ couple begets anti-photoaging and sunburn alleviation. The bandgap-engineered QD composites demonstrated synergistic suppression of oxidative stress development and remarkable cell viability (≥90%) even under UV irradiation. These underlying principles can be extended to prevent and treat other ROS-induced skin ailments. Incorporating VO●-CeO2(0.3)/ZnO(0.7)@β-CD QDs as active ingredients in commercial sunscreens unveiled a substantial enhancement in overall sun protection and antioxidative efficacy. Thus, it is envisioned that VO●-CeO2(x)/ZnO(1-x)@β-CD QD composites hold promise for developing safe, efficacious, and economical sunscreens.