Iron oxide/silver-doped iron oxide nanoparticles: facile synthesis, characterization, antibacterial activity,...

Iron oxide nanoparticles (IONPs) are extremely sought after due to their antibacterial, antioxidant, and anticancer properties. IONPs were synthesized from Pseudomonas aeruginosa kb1 extracellular supernatant extract. After 48 h at 37 °C in the precursor iron salt, the weak yellow culture supernatant turned yellowish-brown and brown-black, confirming IONP production. To make Ag-doped IONPs, sodium borohydride (NaBH₄) reduced the silver nitrate (AgNO₃) salt on the biosynthesized IONPs. SEM showed that the nanoparticles clustered and had a uniform size distribution and approximately spherical shape. EDX and XRD analysis validated the production of maghemite (γ-Fe₂O₃) and magnetite (Fe₃O₄) IONPs. Fourier transform infrared spectroscopy determined the surface functional groups of Ag-doped and IONPs. The antibacterial activity of Fe₃O₄ and Ag-doped Fe₃O₄ NPs against numerous harmful bacterial strains was much higher than that of Fe₂O₃. The normal retina cell line and human lung cancer cell line A549 were also tested for cytotoxicity using the MTT assay. Ag-doped Fe₃O₄ NPs were more cytotoxic than IONPs on A549 cells. Therefore, the biosynthesized Ag-doped Fe₃O₄ NPs, rather than IONPs, have potential applications as pharmaceutical and therapeutic products because they are safe, eco-friendly, and cost-effective.