Cerium oxide nanoparticles are potent antioxidants, based on their ability to either donate or receive electrons as they alternate between the +3 and +4 valence states. The dual oxidation state of ceria has made it an ideal catalyst in industrial applications, and more recently, nanoceria's efficacy in neutralizing biologically generated free radicals has been explored in biological applications. Here, we report the in vivo characteristics of custom-synthesized cerium oxide nanoparticles (CeNPs) in an animal model of immunological and free-radical mediated oxidative injury leading to neurodegenerative disease. The CeNPs are 2.9 nm in diameter, monodispersed and have a -23.5 mV zeta potential when stabilized with citrate/EDTA. This stabilizer coating resists being 'washed' off in physiological salt solutions, and the CeNPs remain monodispersed for long durations in high ionic strength saline. The plasma half-life of the CeNPs is ∼4.0 h, far longer than previously described, stabilized ceria nanoparticles. When administered intravenously to mice, the CeNPs were well tolerated and taken up by the liver and spleen much less than previous nanoceria formulations. The CeNPs were also able to penetrate the brain, reduce reactive oxygen species levels, and alleviate clinical symptoms and motor deficits in mice with a murine model of multiple sclerosis. Thus, CeNPs may be useful in mitigating tissue damage arising from free radical accumulation in biological systems.

Nanoceria is an exceptionally versatile, commercially valuable catalytic material whose properties vary dramatically from that of the bulk material.

Nanoceria was produced by an aqueous precipitation technique in the presence of an organic stabilizer. The stable suspensions were diafiltered to remove reaction byproducts. Particles were characterized by transmission electron microscopy with images used to size the particles, and selected-area electron diffraction was used to determine the lattice structure and the lattice constant. For all particles studied, the electron diffraction data were consistent with that of CeO2 and not Ce2O3, as predicted by some researchers for very small particles sizes. At particle diameters of ∼1 nm, the lattice expansion approached 7%. In agreement with earlier researchers, we interpret this effect as due to the formation of substantial amounts of Ce3+ with corresponding oxygen vacancies, but within the fluorite lattice structure of CeO2. Even at a particle size of 1 nm, there was a measurable oxygen storage capacity, consistent with a still-reducible CeO2 structure, rather than the fully oxidized Ce2O3.

Articles you may be interested inCross sections and photoelectron angular distributions in photodetachment from negative ions using equation-ofmotion coupled-cluster Dyson orbitals Threshold laws for the cross section for photodetachment of electrons from polyatomic negative ions are derived. The general form for the limiting behavior at threshold is derived using group theory and symmetry considerations. In addition, for energies within a few eV of threshold, a formulation using the Born approximation with partial orthogonalization is developed. The energy dependence of the photodetachment cross section for molecular negative ions is computed and shown to agree well with experimentally determined cross sections.

Nanoceria redox properties are affected by particle size, particle shape, surface chemistry, and other factors, such as additives that coat the surface, local pH, and ligands that can participate in redox reactions. Each CeO 2 crystal facet has a different chemistry, surface energy, and surface reactivity. Unlike nanoceria's industrial catalytic applications, biological and environment exposures are characterized by high water activity values and relatively high oxygen activity values. Electrochemical data show that oxygen levels, pH, and redox species affect its phase equilibria for solution and dissolution. However, not much is known about how the many and varied redox ligands in environmental and biological systems might affect nanoceria's redox behaviour, the effects of coated surfaces on redox rates and mechanisms, and whether the ceria solid phase undergoes dissolution at physiologically relevant pH and oxygen levels.Research that could answer these questions would improve our understanding of the links between nanoceria's redox performance and its morphology and environmental conditions in the local milieu.(111) FACE Dissociative water adsorption creates two types of hydroxyl on this face, Ce 1 -OH (sitting on top of a cerium atom) and Ce 3 -OH (sitting on top of the intersection of three co-shows the crystal facets investigated, the method, and the typical conditions considered. Several research groups have studied water adsorption 89-94 and hydroxyl stability 95 on nanoceria. Table 4. Computational studies of nanoceria. QCMD = quantum chemical molecular dynamics; DFT = density functional theory; SRPES = synchrotron radiation photoelectron spectroscopy. Condition Crystal facets Method Ref. Low water activity CO adsorption (110), slab