Green Synthesis, Characterization and Antioxidant Activity of Chitosan-Coated Iron Oxide Nanoparticles from Ficus platyphylla

Green synthesis using plant extract is an eco-friendly approach for producing metal oxide nanoparticles with improved biological activity. This study investigated the green synthesis of iron oxide nanoparticles (FeONPs) using Ficus platyphylla leaf extract and determine how chitosan influences their surface characteristics and antioxidant activity. The FeONPs were synthesized using aqueous Ficus platyphylla leaf extract and subsequently coated with a chitosan. The nanoparticles were characterized using UV-visible spectroscopy, Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and Scanning electron microscopy (SEM). The antioxidant activity of the aqueous extract was determined using 2, 2-diphenyl-1-picrylhydrazyl (DPPH) free radical scavenging and Ferric reducing antioxidant power (FRAP) assays. The UV-visible spectra confirmed successful nanoparticle formation, while the FTIR showed a strong interaction between chitosan functional groups and iron oxide surface. XRD revealed a highly crystalline cubic spinel structure consistent with magnetite/maghemite and SEM revealed irregular aggregated particles with increased surface roughness after chitosan coating. CS-FeONPs showed significantly higher DPPH scavenging activity (IC₅₀ = 11.63 ± 0.30 µg/mL) than uncoated FeONPs (IC₅₀ = 19.53 ± 0.63 µg/mL) and the crude extract (IC₅₀ = 23.02 µg/mL) (p < 0.05), approaching the activity of vitamin C. FRAP analysis similarly demonstrated a gradual increased in reducing power from the extract to FeONPs and further to CS-FeONPs’ Therefore, combining plant mediated synthesis with chitosan surface functionalization produced a stable iron oxide nanocomposite with improved antioxidant activity. These findings highlighted the role of surface engineering in developing sustainable nanomaterials with promising biomedical applications.