Sodium alginate-based Fe2O3/NiO nanocomposite: A green-engineered and sustainable platform for antioxidant, antimicrobial, and catalytic degradation of indigo carmine dye.

Green nanotechnology offers a sustainable pathway for the production of eco-friendly materials with various applications in biomedicine and environmental detoxification. Towards this objective, the present work details a new sodium alginate-supported NiO/Fe2O3 nanocomposite (NC) synthesized via a green route using Rosmarinus officinalis extract and sodium alginate as sustainable reducing and stabilizing agents. Unlike other previously reported NiO- or Fe2O3-based systems, this green-synthesized nanocomposite is a low-cost and eco-friendly path with enhanced multifunctional performance. Characterization by UV-Vis, FTIR, TEM, SEM, XRD, and EDX, with NiO/Fe2O3 nanoparticles measuring below 50 nm and NiO/Fe2O3/alginate NC exhibiting smaller, well-dispersed particles in the 10-30 nm range within the alginate framework. The prepared nanocomposite has enhanced antioxidant activity (IC50 = 0.130 mg/mL) and enhanced antimicrobial activity against certain resistant bacteria like K. pneumoniae and S. aureus. Catalytic degradation of indigo carmine dye was optimized statistically for the first time, applying the Taguchi approach using a mixture of NiO/Fe2O3 and NiO/Fe2O3/alginate NCs as the catalytic system, achieving 94.89 ± 1.18% removal under optimal conditions (5 h, 60 °C). Early biocompatibility tests indicate that as-synthesized NC is not toxic, further establishing the safety of its use in biomedical and environmental remediation applications. This low-cost, biocompatible, and eco-friendly nanocomposite is extremely promising in actual applications for water purification, environmental remediation, and biomedical treatment strategies.