Synergistic Effect of Magnetic Iron Oxide Nanoparticles with Medicinal Plant Extracts against Resistant Bacterial Strains

Nanoparticles are emerging as a fascinating alternative to antibiotics. When stabilized by chemical compounds, magnetite nanoparticles (MagNPs) consistently exhibit bactericidal effects across different types of bacteria. This study describes the synthesis, characterization, and antibacterial properties of magnetite MagNPs prepared by the coprecipitation method under continuous sonication. Scanning Electron Microscopy (SEM), X-ray Diffraction (XRD), and Dynamic Light Scattering (DLS) techniques revealed Fe3O4-NPs as spherical, uniform particles with an average size of approximately 16 nm. The antibacterial efficacy of MagNPs was investigated by combining them with methanolic extracts of three medicinal plants known for their antibacterial properties: Aloysia triphylla, Sarcopoterium spinosum, and Urtica pilulifera. The combined effect was assessed against both wild type and resistant strains of Staphylococcus aureus and Escherichia coli. The antibacterial synergistic effect of MagNPs and plant extracts was evaluated by the MIC test, which showed significant inhibitory properties against the growth of the four bacterial strains as compared to control samples of plant extracts alone. Furthermore, the synergistic effect of MagNPs combined with extracts from Rosmarinus officinalis, Anchusa azurea, Quercus infectoria, and Urtica pilulifera significantly prevented biofilm development in both sensitive and resistant strains of Staphylococcus aureus.