Abstract
Cerium oxide nanoparticles (CeNPs) represent a highly promising material for a number of chemical and biological applications involving oxidation-reduction processes. However, the impact of synthesis conditions, as well as the incorporation of synergistic agents of a different catalytic nature, on the antioxidant or prooxidant properties of CeNPs remains a subject of ongoing investigation. In this study, non-stoichiometric CeNPs (∼10% Ce(3+)) stabilized by polyvinylpyrrolidone (PVP) were synthesized through the thermal autoxidative decomposition of cerium(iii) nitrate in a high-boiling glycol. A novel approach for the synthesis of CeNPs in the absence of additives (PVP-CeNPs) and with platinum (PVP-CeNPs-Pt), followed by the formation of platinum nanoparticles (PVP-PtNPs), was employed in a stepwise one-pot process. In chemical tests, the PVP-CeNPs-Pt nanocomposite exhibited enhanced peroxidase-mimicking activity and accelerated the Fenton-type reaction of dye decolorization. Nevertheless, it was found to have the ability to reduce adrenaline autoxidation via the superoxide dismutase-mimicking pathway. In vitro studies demonstrated that PVP-CeNPs and PVP-CeNPs-Pt enhanced H(2)O(2)-induced oxytosis while restoring cellular metabolic activity inhibited by the Fenton-like pathway of cellular apoptosis (ferroptosis) initiated by sulfasalazine. The authors suggest that the oxidoreductase activity of CeNP-based systems in the chemical tests and in biological processes in vitro may be caused by different mechanisms, which are discussed.