فهرست نشریات علمی دسترسی آزاد ایران

The present study reports an eco-friendly green synthesis approach for the fabrication of manganese oxide (MnO), iron oxide (Fe₂O₃), and manganese ferrite spinel (MnFe₂O₄) nanoparticles utilizing aqueous extract of Citrus sinensis (orange) peel as a natural reducing and capping agent. The phytochemicals present in the orange peel extract, including flavonoids, phenolic compounds, and ascorbic acid, served as effective bio-reductants for metal ion reduction and stabilization of the resulting nanoparticles. The synthesized nanoparticles were comprehensively characterized using multiple analytical techniques including X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), energy dispersive X-ray spectroscopy (EDX), and vibrating sample magnetometry (VSM). XRD analysis confirmed the successful formation of crystalline phases with average crystallite sizes of 14.05 nm for MnO, 24.17 nm for α-Fe₂O₃ (hematite), and 30.66 nm for MnFe₂O₄ spinel structure, calculated using the Debye-Scherrer equation. FESEM micrographs revealed predominantly spherical morphology with mean particle sizes of 19.65 ± 3.35 nm, 24.29 ± 1.48 nm, and 31.31 ± 3.92 nm for MnO, Fe₂O₃, and MnFe₂O₄, respectively, as determined by Gaussian distribution analysis. EDX spectroscopy confirmed the elemental composition and stoichiometric ratios of the synthesized nanoparticles without significant impurities. VSM measurements revealed superparamagnetic behavior for MnFe₂O₄ nanoparticles, making them suitable for biomedical applications. The antibacterial efficacy was systematically evaluated against Gram-negative Escherichia coli (ATCC 25922) and Gram-positive Staphylococcus aureus (ATCC 25923) using the agar well diffusion method at varying concentrations (62.5-500 µg/mL). Results demonstrated concentration-dependent antibacterial activity for all nanoparticles. Notably, MnFe₂O₄ nanoparticles exhibited superior antibacterial performance with maximum inhibition zones of 30 mm and 25 mm against E. coli and S. aureus at 500 µg/mL, respectively. The enhanced antibacterial activity of the mixed metal oxide nanoparticles is attributed to synergistic effects of manganese and iron ions in generating reactive oxygen species (ROS) and disrupting bacterial cell membrane integrity. These findings suggest that green-synthesized MnFe₂O₄ nanoparticles hold significant potential for antimicrobial applications in biomedical and environmental sectors.