Rapid synthesis of magnetic Fe₃O₄/Ag nanocomposite based on a plant-mediated approach and its biological activity

The present study described a quick, efficient, and eco-friendly method for producing Fe₃O₄-Ag nanocomposite (NC) using Mentha pulegium L. plant extract. Ultrasonic-assisted extraction (UAE) was employed to prepare an aqueous extract due to its speed and effectiveness. During the manufacture of Fe₃O₄-Ag NC, the prepared plant extracts were utilized as naturally occurring stabilizing precursors. The study also employed several methods for characterizing the synthesized NC, including X-ray diffraction patterns, which estimated the mean particle size to be 52 nm using the Deby-Scherrer equation. The successful synthesis of Fe₃O₄-Ag NC was approved by a broad absorption band from 400 to 425 nm in the absorption spectrum. Subsequently, the samples' antibacterial, antifungal, and antioxidant potentials (Fe₃O₄ NPs, Ag NPs, Fe₃O₄-Ag NC, and the extract) were investigated. Notably, the NP and NC samples showed higher antibacterial activity than the extract, wherein gram-negative bacteria were more significantly affected than gram-positive bacteria. The Fe₃O₄-Ag NC had MIC values of 0.062 mg/mL against Staphylococcus aureus and Escherichia coli. The Fe₃O₄-Ag NC was found to have a significant detrimental impact on the bacterial membranes of E. coli and S. aureus, as evidenced by the quick release of cytoplasmic components such as protein, nucleic acid, and potassium. The results also showed that the extract and Fe₃O₄-Ag NC samples exhibited strong antioxidant activity. The study recommends further investigation on the application of these metal nanoparticles in the water remediation, agriculture, and food industries due to their strong biological activity.