Bio-inspired iron oxide nanoparticles using Psidium guajava aqueous extract for antibacterial activity

Bio-inspired synthesis of iron oxide nanoparticles (FeONPs) has been carried out by eco-friendly, low cost, and facile method using an aqueous extract of Psidium guajava (PG) leaf as a potential reducing agent. The obtained FeONPs were characterized using X-ray powder diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), UV-visible spectroscopy, Fourier-transform infrared spectroscopy (FTIR), vibrating sample magnetometer (VSM), and energy-dispersive spectroscopy techniques. The surface plasmon resonance peak of FeONPs was found to be 310 nm. The FTIR spectra analysis indicates the presence of various functional groups in PG extract that are responsible for the biosynthesis of FeONPs. The XRD confirmed that FeONPs were indexed into the cubic spinel lattice structure. The SEM and TEM analysis confirmed the spherical morphology of FeONPs with particle size ranging from 1 to 6 nm. The superparamagnetic nature of the formulated FeONPs was determined using VSM. The FeONPs formulated inhibit the growth of six human pathogenic strains with strong activity chiefly against Escherichia coli and Staphylococcus aureus at low concentration when compared to other standard antibacterial drugs. It is noteworthy that the formulated FeONPs are efficient as an antibacterial agent.