Assessment of green-synthesized iron oxide nanoparticles from Trachyspermum ammi and Delonix regia and their potential for anticancer activity

The biocompatible nanoparticles synthesized via the green route have gained huge interest in medicine, especially for cancer treatment. Here, iron oxide nanoparticles (IONPs) were phyto-fabricated using Trachyspermum ammi leaf extract (IONPs-TA) and Delonix regia flower extract (IONPs-DR) and evaluated for their therapeutic potential against a cervical cancer cell line. The most favourable IONPs synthesis conditions were identified in an alkaline pH range of 8–10, at a moderate temperature of 40–50 °C, and in the presence of 1 mM FeCl3. Preliminary evidence of IONP formation was observed by ultraviolet‒visible spectroscopy, with absorption peaks at 280 nm (IONPs-TA) and 342 nm (IONPs-DR). Fourier transform infrared analysis showed characteristic bands for Fe–O in the range of 400–900 cm−1, along with other bands assigned to organic molecules. X-ray diffraction revealed predominantly crystalline α-Fe2O3/Fe3O4-like phases with crystallite sizes of 39.1 nm (IONPs-TA) and 9.6 nm (IONPs-DR), respectively. Dynamic light scattering (DLS) analysis revealed large hydrodynamic diameters due to aggregation in aqueous suspension, with zeta potentials of −19.6 mV and −4.9 mV, respectively, whereas TEM analysis confirmed primary nanoparticle sizes of approximately 40–100 nm. FESEM and TEM analyses revealed that IONPs-TA are quasi-spherical to cuboidal/polyhedral nanoparticles with occasional elongated (nanorod-like) structures with moderate agglomeration (40–100 nm), whereas IONPs-DR are aggregated together along with organic compounds exceeding a size of more than 100 nm. The results of the MTT assay indicated dose-dependent anticancer activity against cervical cancer cells. IONPs-TA exhibited moderate inhibition against the HeLa cell line (IC50 of ~45 µg/mL), whereas IONPs-DR showed stronger activity toward the SiHa cell line (IC50 of ~29 µg/mL). The results revealed that the plant-mediated synthesized IONPs exhibit appreciable anticancer activity, with D. regia-derived IONPs showing higher efficacy.