Biosynthesis, Characterization, and Antibacterial Activity of Manganese Oxide Nanoparticles Synthesized Using Aqueous Extract of Eriobotrya japonica Leaf

Abstract Among the various techniques for synthesizing nanoparticles (NPs), green synthesis is particularly advantageous due to its cost‐effectiveness, biocompatibility, and simplicity. Manganese oxide nanoparticles (Mn 2 O 3 ₃ NPs) were successfully produced using the leaf extract of Eriobotrya japonica . Findings from X‐ray diffraction (XRD), dynamic light scattering (DLS), and field emission scanning electron microscopy (FESEM) confirmed the successful synthesis of the NPs. In this study, Mn 2 O 3 ₃ NPs exhibited significant antibacterial activity, utilizing Escherichia coli as a model microorganism. Antibacterial efficacy was evaluated through plate count and bacterial growth curve methods. The surface plate assay indicated that approximately 41 µg/mL of Mn 2 O 3 NPs could eliminate 99.9% of Escherichia coli . Morphological changes in the bacteria were further examined using SEM, which revealed that the NPs compromised the bacterial cell membrane, leading to its disintegration. The NPs significantly downregulated the expression of genes associated with amino acid metabolism (metL), DNA repair and transcription (mfD), virulence (fliC), and the TCA cycle (aceF) following treatment of Escherichia coli . Results from the MTT assay demonstrated that Mn 2 O 3 NPs are not cytotoxic to a breast cancer epithelial cell line (MCF‐7). These findings suggest that the biosynthesis of Mn 2 O 3 nanoparticles offers a novel strategy for developing antimicrobial agents.