Facile synthesis and characterization of polyethylenimine-coated Fe₃O₄ superparamagnetic nanoparticles for cancer cell separation

The detection of cancer cells in clinical samples is of great interest for a range of diagnostic applications, and separation and enrichment of cancer cells in low concentrations from complex sample matrices is necessary for efficient cancer diagnostics. In the present study, new surface-modified iron oxide nanoparticles were synthesized for the separation of lung cancer cells by simple precipitation of Fe(II) and Fe(III) salts in an aqueous ammonia solution, followed by the addition of polyethylenimine (PEI). The modified nanoparticles were characterized by X-ray diffractometry (XRD), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS) and vibrating sample magnetometry (VSM). XRD and TEM revealed that the particles were ~10 nm in diameter, while FTIR and XPS showed that their surfaces were well coated with PEI. VSM results confirmed the superparamagnetic nature of PEI-coated Fe3O4 nanoparticles. The separation and enrichment of lung cancer cells from sputum samples was demonstrated using the synthesized developed PEI-coated Fe3O4 magnetic nanoparticles. Exfoliative cytopathology showed that the percentage of positive cells increased from 6.3% (38/600) in untreated sputum samples to 38.5% (231/600) in sputum samples treated with PEI-coated Fe3O4 magnetic nanocomposites. This finding indicated that PEI-coated Fe3O4 magnetic nanocomposites can be used to efficiently enrich lung cancer cells from sputum for subsequent cytopathological analysis.