Oxidative Stress Response of Selenium Nanoparticles to Copper Stress in Aspergillus flavus TL-F3

• • At 50 mg·L−1 Cu2+ stress, 0.25 mg·L−1 SeNPs increased A. flavus TL-F3 biomass by 2.71%, demonstrating a protective effect that could enhance fungal biomass production in bioremediation applications. • • SeNPs elevated GPX and GR activities by 17.2% and 23.94%, respectively, and increased GSH content by 18.59%, indicating a strengthened antioxidant defense that mitigates Cu2+-induced oxidative stress. • • The maximum Cu2+ removal rate of 56.32% was achieved at 50 mg·L−1 Cu2+ without SeNPs, establishing a baseline for fungal copper uptake efficiency under optimized conditions. • • FTIR analysis identified carboxylic acid, alcohol, phenol, and phosphate/sulfate groups as potential Cu2+ binding sites, providing a mechanistic basis for biosorption and guiding surface modification strategies.