Photocatalytic Degradation of Coomassie Brilliant Blue R-250 and Antimicrobial Activities of Iron Oxide Nanoparticles Synthesized by Aspergillus flavus.

This study explores the biosynthesis of iron oxide nanoparticles (IONPs) by Aspergillus flavus recovered from The Iron and Steel Factory (Helwan) in EGYPT. Various factors, including metal salt concentration, inoculum size, pH, incubation time, temperature, and aeration, were optimized to enhance nanoparticle production. Characterization of the IONPs was performed using UV-Vis spectroscopy, Dynamic light scattering (DLS), X-ray diffraction (XRD), Transmission electron microscopy (TEM), and Fourier-transform infrared spectroscopy (FTIR). The synthesized IONPs were found to be quasi-spherical with sizes ranging from 7.66 to 49 nm and exhibited an amorphous structure. The photocatalytic activity of the IONPs was evaluated for the degradation of Coomassie Brilliant Blue R-250 under UV light. At pH 3 and with 10 mg/mL IONPs, 61% degradation of 7 ppm dye was achieved after 180 min. The antimicrobial activity of the IONPs was assessed against 8 microbial strains (Aspergillus flavus MT102937, Aspergillus niger MT103092, Aspergillus fumigatus MT103062, Candida albicans CA10231, Escherichia coli ATCC 25922, Shigella sonnei ATCC 29930, Staphylococcus aureus ATCC 6538, and Streptococcus mutans ATCC 25175). The IONPs showed the highest inhibitory effect against Staphylococcus aureus ATCC 6538, with a zone of inhibition of 22.33 ± 0.58 mm, while Aspergillus niger MT103092 was the most sensitive fungal species, showing an inhibition zone of 16.33 ± 1.53 mm. The results highlighting the potential applications of biosynthesized IONPs in environmental remediation and antimicrobial therapies.