pH-Control Azadirachta indica Leaf Extract-Mediated Synthesis of Iron oxide Nanoparticles for Catalytic Degradation of Toxic Dyes and Biomedical Potential

Green synthesis offers an eco-friendly and sustainable route to nanoparticle fabrication by harnessing plant-derived phytochemicals as natural reducing and capping agents. In the present study, iron oxide nanoparticles (IONPs) were biosynthesized using Azadirachta indica (neem) leaf extract under varying pH conditions (3, 6, and 11), demonstrating the profound influence of reaction environment on nanoparticle formation and stability. Multifaceted characterization using UV–Vis spectroscopy, DLS, zeta potential, FESEM, FTIR, XRD, and BET confirmed the formation of stable, highly crystalline iron oxide nanoparticles. pH 6 yielded uniformly dispersed nanorods (50–80 nm broad, 10–20 µm long) with the maximum stability (-28.3 mV). Antioxidant assays showed significant radical scavenging activity, with IC₅₀ values of 78.06 µg/mL (DPPH) and 70.94 µg/mL (ABTS). Catalytic studies revealed effective degradation of methylene blue and eosin yellow dyes, achieving removal efficiencies of ~ 62% and ~ 55% without H₂O₂, and ~ 87% and ~ 83% with H₂O₂ at room temperature within 60 min. These findings highlight the potential of A. indica -mediated IONPs as eco-friendly catalysts for wastewater treatment and as promising agents for biomedical applications.