Nanoarchitectonics with solid state surface dispersion of ceria quantum dots on nano-yttria for efficient photoprotection

The development of multifunctional nanocomposites capable of mitigating ultraviolet (UV)-induced damage without promoting secondary oxidative stress remains a key challenge in advanced photoprotection. In this study, we report a rationally engineered nanocomposite composed of cerium oxide (CeO 2 ) quantum dots (QDs) uniformly dispersed onto a yttrium oxide (Y 2 O 3 ) nanoparticle matrix. This design integrates efficient UV shielding with enhanced reactive oxygen species (ROS) scavenging. Physicochemical characterization confirmed surface-dispersed CeO 2 QDs with an average size of 5.8 ± 1.0 nm and the formation of a defect-rich CeO 2 /Y 2 O 3 heterointerface, evidenced by increased lattice microstrain (1.33 × 10 -3 ) and substantial Ce 3+ enrichment (35.9% compared with 16.5% in pure CeO 2 ). Crucially, the surface anchoring of the CeO 2 QDs on the Y 2 O 3 matrix helped maintain their nanoscale dispersion and limit aggregation. This stabilization enhanced both ROS-scavenging performance and biocompatibility by maintaining a uniform distribution of active sites. In vitro studies using HaCaT keratinocytes demonstrated excellent biocompatibility through mitigation of the inherent cytotoxicity of Y 2 O 3 and revealed a more than threefold increase in clonogenic survival following UV exposure compared to untreated controls. This protective effect outperformed Y 2 O 3 and closely approached that of pure CeO 2 , despite the nanocomposite containing a relatively low cerium content of 10.93 wt%, used exclusively in quantum dot form. These findings underscore the importance of interfacial strain, surface anchoring, and nanoscale dispersion in enhancing photoprotective performance while minimizing the required amount of active material. This strategy presents a scalable approach for developing safe and effective UV-protective nanomaterials.