Abstract
Growing concern over the adverse health and environmental effects of conventional organic ultraviolet (UV) filters has driven the search for safer, more environmentally compatible sunscreen technologies. The aim of this study was to develop sunscreen-grade inorganic UV filters that provide broad-spectrum protection while minimizing photocatalytic activity and ecological toxicity, using surface-modified zinc oxide (ZnO) and titanium dioxide (TiO₂) nanoparticles. To reduce the use of hazardous chemicals and improve environmental compatibility, the nanoparticles were prepared by green synthesis using an aqueous extract of Oryza sativa (rice), which acted as both a reducing and a capping agent and enhanced colloidal stability while limiting aggregation. The synthesized nanoparticles were characterized by Fourier-transform infrared (FTIR) spectroscopy and scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM-EDS). FTIR confirmed the binding of rice phytochemicals to the metal-oxide surfaces, and SEM-EDS revealed well-dispersed particles below 100 nm bearing an organic, carbon-rich coating. The antioxidant performance of the formulations was evaluated by DPPH, FRAP, and ABTS assays. In every assay the surface-modified nanoparticles showed substantially higher radical-scavenging and reducing activity than their pristine counterparts, indicating reduced oxidative stress and photocatalytic potential. Together, these results suggest that Oryza sativa surface modification offers an effective, eco-friendly strategy for converting otherwise pro-oxidant mineral UV filters into actively protective antioxidant agents with improved safety and environmental compatibility