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.

中文翻译：

---

使用番石榴水提取物的生物启发氧化铁纳米颗粒具有抗菌活性

氧化铁纳米粒子 (FeONPs) 的仿生合成已通过环保、低成本和简便的方法使用番石榴 (PG) 叶的水提取物作为潜在的还原剂进行。使用 X 射线粉末衍射 (XRD)、扫描电子显微镜 (SEM)、透射电子显微镜 (TEM)、紫外-可见光谱、傅里叶变换红外光谱 (FTIR)、振动样品磁强计 (VSM)、和能量色散光谱技术。发现 FeONPs 的表面等离子体共振峰为 310 nm。FTIR 光谱分析表明 PG 提取物中存在各种负责 FeONP 生物合成的官能团。XRD 证实 FeONPs 被索引到立方尖晶石晶格结构中。SEM 和 TEM 分析证实了 FeONPs 的球形形态，粒径范围为 1 至 6 nm。使用 VSM 确定了配制的 FeONPs 的超顺磁性。与其他标准抗菌药物相比，配制的 FeONP 可在低浓度下抑制六种具有强活性的人类致病菌株的生长，主要针对大肠杆菌和金黄色葡萄球菌。值得注意的是，配制的 FeONPs 作为抗菌剂是有效的。与其他标准抗菌药物相比，配制的 FeONP 可在低浓度下抑制六种具有强活性的人类致病菌株的生长，主要针对大肠杆菌和金黄色葡萄球菌。值得注意的是，配制的 FeONPs 作为抗菌剂是有效的。与其他标准抗菌药物相比，配制的 FeONP 可在低浓度下抑制六种具有强活性的人类致病菌株的生长，主要针对大肠杆菌和金黄色葡萄球菌。值得注意的是，配制的 FeONPs 作为抗菌剂是有效的。