Green synthesis of gold nanoparticles supported over the Myrtus communis L extract modified magnetic iron oxide as a novel antibacterial agent

Myrtus communis L extract, as an herbal substance with carbonyl and phenolic hydroxyl functional groups, can be applied to functionalize the surface of Fe₃O₄ nanoparticles (NPs). In addition, it can enhance the surface characteristics of the magnetite core for anchoring and reduction of gold ions via complexation in an aqueous medium. Then, Fe₃O₄@ Myrtus communis extract was able to reduce, stabilize, and adhere to gold nanoparticles (Au NPs) to fabricate a new magnetic gold nanocomposite. The morphological, structural, and physicochemical properties of the samples were studied by Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), energy dispersive X-ray spectroscopy (EDS), and transmission electron microscopy (TEM). FT-IR results depicted that the flavonoids, phenolics, and tannins from M. communis extract can play significant roles in reducing and immobilizing Au NPs. Their antibacterial properties were evaluated thoroughly against pathogenic bacterial strains of Gram-positive (Staphylococcus aureus, Enterococcus faecalis) and Gram-negative (Escherichia coli and Pseudomonas aeruginosa) utilizing the agar disc diffusion approach. In addition, MIC (Minimum Inhibitory Concentration) and MBC (Minimum Bactericidal Concentration) were obtained by employing the macro dilution method. Thus, the fabricated Fe₃O₄@M. communis/Au nanocomposite could serve as an effective antimicrobial agent to overcome multi-drug-resistant bacteria.