Surface Study of Fe3O4 Nanoparticles Functionalized With Biocompatible Adsorbed Molecules.

Beata Lesiak,I Gordeev,L Kövér,J Tóth,P Jiricek,N Rangam,M Mohai,P Borowicz

doi:10.3389/fchem.2019.00642

Abstract

Surfaces of iron oxide of ferrimagnetic magnetite (Fe3O4) nanoparticles (MNPs) prepared by Massart's method and their functionalized form (f-MNPs) with succinic acid, L-arginine, oxalic acid, citric acid, and glutamic acid were studied by dynamic light scattering (DLS), Fourier transform infrared spectroscopy (FTIR-S), UV-vis, thermogravimetric analysis (TGA)/differential scanning calorimetry (DSC), X-ray photoelectron spectroscopy (XPS), and reflection electron energy loss spectroscopy (REELS). The XPS analysis of elements and their chemical states at the surface of MNPs and f-MNPs revealed differences in chemical bonding of atoms, content of carbon–oxygen groups, iron oxide forms, iron oxide magnetic properties, adsorbed molecules, surface coverage, and overlayer thickness, whereas the Auger parameters (derived from XPS and Auger spectra) and elastic and inelastic scattering probabilities of electrons on atoms and valence band electrons (derived from REELS spectra) indicated modification of surface charge redistribution, electronic, and optical properties. These modified properties of f-MNPs influenced their biological properties. The surfaces biocompatible for L929 cells showed various cytotoxicity for HeLa cells (10.8–5.3% of cell death), the highest for MNPs functionalized with oxalic acid. The samples exhibiting the largest efficiency possessed smaller surface coverage and thickness of adsorbed molecules layers, the highest content of oxygen and carbon–oxygen functionalizing groups, the highest ratio of lattice O2− and OH− to C sp2 hybridizations on MNP surface, the highest ratio of adsorbed O− and OH− to C sp2 hybridizations on adsorbed molecule layers, the closest electronic and optical properties to Fe3O4, and the lowest degree of admolecule polymerization. This high cytotoxicity was attributed to interaction of cells with a surface, where increased content of oxygen groups, adsorbed O−, and OH− may play the role of additional adsorption and catalytic sites and a large content of adsorbed molecule layers of carboxylic groups facilitating Fenton reaction kinetics leading to cell damage.

Highlights

The iron oxide nanoparticles, i.e., ferrimagnetic maghemite (γ-Fe2O3) with Fe3+ vacancies and ferrimagnetic magnetite (Fe3O4 ≡ FeOFe2O3) with Fe2+ and Fe3+ vacancies, have already been applied in the field of medicine due to their biocompatibility, biodegradability, and possibility to tailor magnetic behavior (Sangaiya and Jayaprakash, 2018), where the change of nanoparticle size, morphology, agglomeration, magnetic, and electronic properties influences the biological effect (Liu et al, 2016)
The reason for the different cytotoxicity of Fe3O4 magnetite (Fe3O4) nanoparticles (MNPs) functionalized with oxalic, succinic, glutamic acids, and Larginine for HeLa cells was investigated by X-ray photoelectron spectroscopy (XPS), X-ray excited Auger electron spectroscopy (XAES), and reflected electron loss spectroscopy (REELS) revealing the chemical groups at the surface and modification of surface electronic properties
It leads to variation in cytotoxicity on HeLa cells decreasing in the order III ≈ I > V > IV > II due to chemical and morphology modification of Fe3O4 MNPs

Summary

INTRODUCTION

The iron oxide nanoparticles, i.e., ferrimagnetic maghemite (γ-Fe2O3) with Fe3+ vacancies and ferrimagnetic magnetite (Fe3O4 ≡ FeOFe2O3) with Fe2+ and Fe3+ vacancies, have already been applied in the field of medicine due to their biocompatibility, biodegradability, and possibility to tailor magnetic behavior (Sangaiya and Jayaprakash, 2018), where the change of nanoparticle size, morphology, agglomeration, magnetic, and electronic properties influences the biological effect (Liu et al, 2016). The reason for the different cytotoxicity of Fe3O4 MNPs functionalized with oxalic, succinic, glutamic acids, and Larginine for HeLa cells was investigated by X-ray photoelectron spectroscopy (XPS), X-ray excited Auger electron spectroscopy (XAES), and reflected electron loss spectroscopy (REELS) revealing the chemical groups at the surface and modification of surface electronic properties. These studies were supported by dynamic light scattering (DLS), Fourier transform infrared spectroscopy (FTIR-S), UV-vis, thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC). The electron beam parameters were as follows: a primary electron energy of 4 keV, a beam current of about 11.5 nA measured with a Faraday cup, and electron incidence and emission angles of 50◦ and 0◦ with respect to the surface normal of the specimen, respectively

RESULTS AND DISCUSSION

CONCLUSIONS

DATA AVAILABILITY STATEMENT