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Although magnetic targeting iron nanoparticles serve as platforms for attaching drugs like, e.g., doxorubicin (DOX), they were also applied in a tumor therapy, which resulted in a hyperthermia and oxidative stress leading to tumor cell damage ( Rangam et al., 2017 Petran et al., 2018 Sangaiya and Jayaprakash, 2018). Fe 2O 3) with Fe 2+ and Fe 3+ 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 iron oxide nanoparticles, i.e., ferrimagnetic maghemite (γ-Fe 2O 3) with Fe 3+ vacancies and ferrimagnetic magnetite (Fe 3O 4 ≡ FeO 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. 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 O 2− and OH − to C sp 2 hybridizations on MNP surface, the highest ratio of adsorbed O − and OH − to C sp 2 hybridizations on adsorbed molecule layers, the closest electronic and optical properties to Fe 3O 4, and the lowest degree of admolecule polymerization. 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. These modified properties of f-MNPs influenced their biological properties. 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. Surfaces of iron oxide of ferrimagnetic magnetite (Fe 3O 4) 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). 4Research Centre for Natural Sciences, Institute of Materials and Environmental Chemistry, Hungarian Academy of Sciences, Budapest, Hungary.3Institute for Nuclear Research, Hungarian Academy of Sciences, Debrecen, Hungary.2Institute of Physics, Academy of Sciences of the Czech Republic, Prague, Czechia.1Institute of Physical Chemistry, Polish Academy of Sciences, Warsaw, Poland.We observed that Cu core addition to copper oxide improves absorption of CO gas.Beata Lesiak 1 *, N. Background of XPS spectra is assigned to the scattering photoelectrons from Cu ions and plasmon of Cu nanoparticles. The CuO/Cu 2O ratio that is obtained by deconvolution of Cu 2p 3/2 main peak and from intensity ratio of the main and satellite peak of Cu 2p 3/2 are consistent. Several interesting information are obtained from XPS study of these core-shells nanoparticles. Surface plasmon resonance (SPR) peak that is signature of the existence of the Cu core nanoparticles appears in visible spectra of these films. The results are indicative that the shell of nanoparticle is mainly Cu 2O phase with CuO cover thin layer. X-ray photoelectron spectroscopy (XPS) characterization indicates that the surface of the Cu nanoparticles oxidizes when they are exposed to air. The samples with different Cu concentration and Cu nanoparticle with different size are grown. 2O core-shell nanoparticles on the a-C:H thin films are prepared by co-deposition of RF-Sputtering and RF-PECVD.