Eco‐Friendly Synthesis of Iron Oxide Nanoparticles From Allium cepa L. Dry Peel Waste With Anticancer and Antibacterial Activities

ABSTRACT Iron oxide nanoparticles (IONPs) were synthesized using dry red onion peel waste (ROPW) ( Allium cepa L.) extract as both a reducing and capping agent. The synthesized nanoparticles were characterized by x‐ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, field‐emission scanning electron microscopy coupled with energy‐dispersive x‐ray spectroscopy (FESEM–EDX), and transmission electron microscopy (TEM). Structural analysis confirmed the formation of crystalline IONPs with a quasi‐spherical morphology and particle size ranging from 14.5 to 45 nm. EDX analysis verified Fe and O as the major constituent elements, while XRD analysis revealed the formation of Fe 2 O 3 and Fe 3 O 4 crystalline phases. The cytotoxic effect of IONPs on hepatocellular carcinoma (HepG2) cells was assessed using the dimethylthiazolyltetrazolium bromide (MTT) assay and scratch wound‐healing assay. The nanoparticles exhibited dose‐ and time‐dependent antiproliferative effects, with IC 50 values decreasing from 50 µg/mL at 24 h to 6.12 µg/mL at 72 h, and significantly inhibited cell migration. Antibacterial activity was evaluated against Gram‐positive and Gram‐negative bacteria. The IONPs showed higher antibacterial activity against Gram‐positive bacteria than Gram‐negative bacteria. Overall, these findings demonstrate that agricultural waste‐derived IONPs can be produced through a sustainable and cost‐effective green synthesis approach and possess promising antibacterial and anticancer properties.