Cerium oxide nanoparticles (CeO₂ NPs) are well known for their application in various fields of industry, as well as in biology and medicine. Knowledge of synthesis schemes, physicochemical and morphological features of nanoscale CeO₂ is important for assessing their antioxidant behavior and understanding the mechanism of oxidative stress and its consequences. The choice of the method of synthesis should be based on the possibility to choose the conditions and parameters for obtaining CeO₂ with controlled dimensions and a ratio of Се³⁺/Се⁴⁺ on their surface. In this study, CeO₂ NPs are synthesized by precipitation in mixed water-alcohol solutions at constant pH = 9. The properties of obtained NPs are studied using various methods of physical-chemical characterization such as X-ray diffraction, X-ray photoelectron spectroscopy, transmission electron microscopy, and dynamic light scattering. The size of CeO₂ NPs varied from 14 to 4.2 nm with increasing alcohol concentration, while the effect of constant pH during synthesis on the morphology of the particles was insignificant. The synthesized nanoparticles form highly stable aqueous suspensions since their zeta-potential is higher than + 40 mV. It is found that the ability of CeO₂ NPs to self-stabilize is associated with the presence of hydrated Ce⁴⁺ ions on their surface. In vitro biological studies have shown that, regardless of particle size, CeO₂ NPs have antioxidant potential, but smaller NPs with a higher percentage of Ce³⁺ on the surface had a more effective antioxidant effect. In addition, the size-depended activity of CeO₂ NPs to inhibit the amyloid formation of insulin is demonstrated.

Fe-doped La0.77Sr0.23Mn1 − y Fe y O3 nanoparticles have been synthesized by sol-gel method, and ceramic samples based on them were sintered at 1613 K. Crystallographic and magnetic properties of obtained nanoparticles and ceramic samples have been studied. It has been established that cell volume for nanoparticles increases with growing of iron content, while this dependence displays an opposite trend in the case of ceramic samples. Mössbauer investigations have shown that in all samples, the oxidation state of iron is +3. According to magnetic studies, at room temperature, both nanoparticles and ceramic samples with y ≤ 0.06 display superparamagnetic properties and samples with y ≥ 0.08 are paramagnetic. Magnetic fluids based on La0.77Sr0.23Mn1 − y Fe y O3 nanoparticles and aqua solution of agarose have been prepared. It has been established that heating efficiency of nanoparticles under an alternating magnetic field decreases with growing of iron content.

Nanoparticles of lanthanum-strontium manganite were synthesized via different methods, namely, sol-gel method, precipitation from non-aqueous solution, and precipitation from reversal microemulsions. It was shown that the use of organic compounds and non-aqueous media allowed significantly decreasing of the crystallization temperature of nanoparticles, and the single-phased crystalline product was formed in one stage. Morphology and properties of nanoparticles depended on the method and conditions of the synthesis. The heating efficiency directly depended on the change in the magnetic parameters of nanoparticles, especially on the magnetization. Performed studies showed that each of these methods of synthesis can be used to obtain weakly agglomerated manganite nanoparticles; however, particles synthesized via sol-gel method are more promising for use as hyperthermia inducers. PACS: 61.46.Df 75.75.Cd 81.20. Fw