Broccoli-mediated green synthesis of selenium nanoparticles with potent antioxidant and antimicrobial activities: Experimental and molecular docking insights

• Green-synthesized selenium nanoparticles produced using Brassica oleracea extract. • Nanoparticles exhibit potent antioxidant and broad-spectrum antimicrobial activity. • Strong inhibition of bacterial biofilm formation and fungal growth demonstrated. • Photocatalytic degradation of Congo Red dye confirmed under visible light. • Characterization revealed stable, spherical SeNPs with uniform size distribution. The increasing demand for environmentally sustainable nanomaterials has encouraged the development of green synthesis approaches utilizing plant-derived biomolecules. In this study, Brassica oleracea (Broccoli) extract was used as a natural reducing agent for the eco-friendly synthesis of selenium nanoparticles (SeNPs). The formation of SeNPs was visually confirmed by a colour change from pale green to reddish-brown and validated by a UV-Visible absorption peak at 266 nm, indicating surface plasmon resonance. FTIR analysis revealed the involvement of hydroxyl, carbonyl, and amide groups in the reduction and stabilization process. The nanoparticles exhibited an average particle size of 89.1 nm and a zeta potential of -31.6 mV, signifying good colloidal stability. The synthesized SeNPs showed strong antibacterial and antifungal activity against Staphylococcus aureus, Escherichia coli , and Aspergillus niger , with zones of inhibition reaching up to 23.67 ± 0.58 mm. Significant antioxidant activity was observed, with a maximum DPPH radical scavenging activity of 56.78 ± 0.92% at 100 µg/mL. The SeNPs also exhibited notable antibiofilm activity, achieving inhibition of up to 73.38 ± 0.66%, and demonstrated efficient photocatalytic degradation of Congo Red dye under sunlight exposure. These findings highlight the multifunctional potential of broccoli-mediated SeNPs and emphasize their relevance as eco-friendly nanomaterials for antimicrobial and antioxidant applications. The study provides experimental evidence supporting plant-based selenium nanoparticle synthesis as a sustainable strategy for developing functional nanomaterials with prospective biomedical and environmental significance.