Eco-friendly synthesis of Fe2O3 nanoparticles using Eucalyptus globulus leaf extract with multifunctional photocatalytic, antioxidant and antibacterial activities.

The green synthesis method was developed to manufacture of iron oxide nanoparticles using Eucalyptus globulus leaf extract as a reducing and stabilizing agent. Identification of Prepared Nanoparticles the identity of synthesized nanoparticles was unequivocally determined as α-Fe2O3 (hematite) from XRD analysis showing the rhombohedral crystal structure (JCPDS No: 33-0664); earlier drafts inconsistently referred to preparation as Fe3O4 and this has been changed throughout this manuscript for consistency. SEM, EDX, FTIR XRD and DLS were used to characterize the morphology, composition and structure of the nanoparticles. Particles on the other hand, had quasi-spherical morphology as well as relatively low average diameters (10.84 ± 5.22 nm) and high crystallinity. FTIR analysis validates the potential role of phytomolecules as capping and stabilizing agents. The photocatalytic experimental notation corrected: almost ~99% degradation of Rhodamine B dye under visible light irradiation (λ ≥ 420 nm) in 340 min pseudo-first-order kinetics (k = 0.0079 min-1). Antioxidant activity of HDPC using DCFH-DA assay: DCFH-DA assay for the measurement of intracellular ROS was performed on the different concentrations (0, 0.1, 0.5, and 2 mg/ml) of EPE which confirmed a concentration-dependent reduction of intracellular ROS in HDPC with ~70% reduction in fluorescence at the highest delivery rate (0.5 mg/ml). The reduction in ROS observed was indicative of real antioxidant activity as cell viability (MTT assay) confirmed this effect to be non-cytotoxic. It exhibited pronounced antibacterial activity against Escherichia coli, Staphylococcus aureus and Bacillus subtilis (ATCC 6633), with S. aureus being the most sensitive strain. MIC values: S. aureus 0.25 mg/ml; E. coli 0.50 mg/ml; B. subtilis 0.50 mg/ml. The green Fe2O3 nanoparticles exhibited multifunctional photocatalytic properties, as well as antioxidant and antibacterial activity, making them novel frontline agents for environmental remediation and biomedicine.