Preparation and antibacterial activity of Fe₃O₄@Ag nanoparticles

TLDR

Fe₃O₄@Ag nanoparticles were synthesized by reducing silver nitrate on Fe₃O₄ cores in a water‑in‑oil microemulsion, yielding superparamagnetic, antibacterial particles whose activity was assessed by MIC, flow cytometry, and antibacterial‑rate assays. Transmission electron microscopy, dynamic light scattering, X‑ray diffraction, and UV–vis confirmed 60 ± 20 nm, Fe₃O₄/Ag composition and superparamagnetism, and the particles exhibited strong antibacterial effects against E.

Abstract

Bifunctional Fe3O4@Ag nanoparticles with both superparamagnetic and antibacterial properties were prepared by reducing silver nitrate on the surface of Fe3O4 nanoparticles using the water-in-oil microemulsion method. Formation of well-dispersed nanoparticles with sizes of 60 ± 20 nm was confirmed by transmission electron microscopy and dynamic light scattering. X-ray diffraction patterns and UV–visible spectroscopy indicated that both Fe3O4 and silver are present in the same particle. The superparamagnetism of Fe3O4@Ag nanoparticles was confirmed with a vibrating sample magnetometer. Their antibacterial activity was evaluated by means of minimum inhibitory concentration value, flow cytometry, and antibacterial rate assays. The results showed that Fe3O4@Ag nanoparticles presented good antibacterial performance against Escherichia coli (gram-negative bacteria), Staphylococcus epidermidis (gram-positive bacteria) and Bacillus subtilis (spore bacteria). Furthermore, Fe3O4@Ag nanoparticles can be easily removed from water by using a magnetic field to avoid contamination of surroundings. Reclaimed Fe3O4@Ag nanoparticles can still have antibacterial capability and can be reused.