Green Synthesis of Fe 3 O 4 /ZnO Nanocomposite Using Vernonia amygdalina Leaf Extract for Antibacterial Applications

ZnO/Fe 3 O 4 composite nanostructures synthesized by green methods are of interest because of the interesting combination of magnetic and semiconducting properties that make them appealing in antibacterial domains. In this work, ZnO and Fe 3 O 4 nanoparticles (NPs) and their composite nanocomposite (Fe 3 O 4 @ZnO) were synthesized and characterized to test the antibacterial activity. The prepared materials were analyzed by different methods including XRD, FTIR, and SEM. The XRD patterns showed the unique crystalline types of the materials; that is, ZnO had a hexagonal wurtzite‐type structure, and Fe 3 O 4 had an inverse spinel structure. The achieved peaks of ZnO and Fe 3 O 4 in the Fe 3 O 4 @ZnO nanocomposite suggested that both phases coexisted. The composite also exhibits a reduced crystallite size as compared to the pure Fe 3 O 4 NPs. To check antibacterial properties, the materials were tested against common bacterial strains: Escherichia coli , Pseudomonas aeruginosa , Staphylococcus aureus , and Streptococcus pyogenes . The results showed that the Fe 3 O 4 @ZnO nanocomposite shows significantly stronger antibacterial effects than the individual NPs, with larger inhibition zones in the disk diffusion assays. This improved antibacterial activity success results from the synergistic interaction between ZnO and Fe 3 O 4 , which improves stability and increases the generation of reactive oxygen species (ROS). This study shows the Fe 3 O 4 @ZnO nanocomposite as the best candidate for a variety of antibacterial applications due to its high performance and multifunctional properties.