Biogenic mediated synthesis, characterization, antimicrobial and radical scavenging studies of iron oxide nanoparticles (Fe3O4-NPs) using Eichhornia crassipes leaves extract

The plant Eichhornia crassipes (commonly known as water hyacinth) was obtained from Lake Geriyo, Yola, Adamawa State, Nigeria. The sampled leaves were gently washed with deionized (DI) water and air-dried at room temperature (25–30 °C). Iron nanoparticles were synthesized using Eichhornia crassipes (water hyacinth extract) and characterized using XRD, SEM, TEM, SEM-EDX, and FTIR. The antioxidant activity of the iron nanoparticles was analyzed using DPPH scavenging activity. The plant extracts and iron nanoparticles were tested for antibacterial efficiency against Escherichia coli, Staphylococcus aureus, Streptococcus pneumoniae, Salmonella typhi, and Klebsiella pneumoniae. The results revealed the proximate composition of the water hyacinth plant, including moisture content, ash content, fiber, fat content, protein, and carbohydrates. The proximate composition followed the order: carbohydrates > lipids > fiber > moisture > protein > ash content. Qualitative phytochemical screening of the leaf revealed the presence of carbohydrates, terpenoids, phenolics, and saponins, while amino acids, terpenes, alkaloids, steroids, and flavonoids were absent. SEM-EDX, TEM, XRD, and FTIR confirmed the formation of iron nanoparticles. The iron nanoparticles exhibited higher percentage inhibition with varied concentrations of 25% FeNPs, 50/50 FeNPs, and 25/75 FeNPs, with 25/75 FeNPs showing significant scavenging activity of 24%, 39%, 47%, 55%, and 73% at 10, 20, 30, 40, and 50 µl/ml, respectively. The minimum inhibitory concentration (MIC) of 25% FeNPs for Klebsiella pneumoniae and Staphylococcus aureus showed that the extract had a higher inhibitory effect on Klebsiella pneumoniae compared to Staphylococcus aureus. The inhibition sequence showed similar inhibition for all pathogens except Salmonella typhi and Klebsiella pneumoniae, which exhibited the least inhibition among all FeNP concentrations. An increase in material concentration resulted in higher inhibition for four organisms, while Klebsiella pneumoniae showed a different trend, with the highest inhibition observed at a 200 µg/L concentration.