In this study, selenium nanoparticles (SeNPs) were synthesized on the surface of graphene oxide (GO) nanosheets using agricultural waste material, Saffron (Crocus sativus L.) petals extract (SPE). Owing to the high anthocyanin content, SPE acted as a capping and reducing agent during the synthesis of rGO.Se nanocomposites (rGO.SeNCs). The crystal structure, morphology, and chemical composition of rGO.SeNCs were determined and their potential as an antioxidant, antibacterial, and anticancer agent was investigated. The results showed that spherical SeNPs were regular in shape with a mean diameter of 180–250 nm and evenly distributed and adhered to the rGO matrix. In vitro antioxidant assay revealed a higher radical scavenging capacity of rGO.SeNCs, especially against hydroxyl and superoxide radicals, than GO nanosheets. Moreover, rGO.SeNCs showed far superior antibacterial activity against Gram-positive bacteria compared to SeNPs alone and bare GO nanosheets. Based on cytotoxic results, rGO.SeNCs significantly diminished the growth rate of breast cancer cells (4T1 and MCF7 cells) without adverse effects on normal cells (NIH3T3 cells), indicating the biocompatibility and selective cancer-killing capacity of the synthesized nanocomposites. rGO.SeNCs caused the loss of mitochondrial membrane integrity and apoptosis following the rise of reactive oxygen species (ROS) and the disturbance of intracellular redox status. Collectively our results disclosed a facile and eco-friendly route for the fabrication of rGO.SeNCs and depicted their multifunctional efficiency as an antioxidant, antibacterial, and anticancer agent that could be employed in biomedical fields.

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