New facets of nanozyme activity of ceria: lipo- and phospholipoperoxidase-like behaviour of CeO2 nanoparticles†
Cerium dioxide nanoparticles have a special place among engineered nanomaterials due to the wide range of their enzyme-like activities. They possess SOD-, catalase- and peroxidase-like properties, as well as recently discovered phosphatase-, photolyase-, phospholipase- and nuclease-like properties. Advancing biomedical applications of CeO2-based nanozymes requires an understanding of the features and mechanisms of the redox activity of CeO2 nanoparticles when entering the vascular bed, especially when interacting with lipid-protein supramolecular complexes (biomembranes and lipoproteins). In this paper, CeO2 nanoparticles are shown to possess two further types of nanozyme activity, namely lipo- and phospholipoperoxidase-like activities. Compared to a strong blood prooxidant, hemoglobin, CeO2 nanoparticles act as a mild oxidising agent, since they exhibit a 106 times lower, and 20 times lower, prooxidant capacity towards linoleic acid and phosphatidylcholine hydroperoxides, respectively. Compared to the widespread pharmacological preparation of iron, Fe(III) carboxymaltose (antianemic preparation Ferinject®), the prooxidant capacity of CeO2 nanoparticles towards lipid and phospholipid substrates has been shown to be 102 times lower, and 4 times higher, respectively. The data obtained on the mechanism of the interaction of nanodisperse CeO2 with the main components of biological membranes, lipids and phospholipids enable the substantial expansion of the scope of biomedical applications of CeO2 nanozymes.