Redox enzyme-mimicking activities of CeO2 nanostructures: Intrinsic influence of exposed facets

Abstract

CeO2 nanoparticles (NPs) have been well demonstrated as an antioxidant in protecting against oxidative stress-induced cellular damages and a potential therapeutic agent for various diseases thanks to their redox enzyme-mimicking activities. The Ce3+/Ce4+ ratio and oxygen vacancies on the surface have been considered as the major originations responsible for the redox enzyme-mimicking activities of CeO2 NPs. Herein, CeO2 nanostructures (nanocubes and nanorods) exposed different facets were synthesized via a facile hydrothermal method. The characterizations by X-ray photoelectron spectroscopy, Raman spectroscopy, and UV-Vis spectroscopy show that the Ce3+/Ce4+ ratio and oxygen vacancy content on the surfaces of as-synthesized CeO2 nanostructures are nearly at the same levels. Meanwhile, the enzymatic activity measurements indicate that the redox enzyme-mimicking activities of as-synthesized CeO2 nanostructures are greatly dependent on their exposed facets. CeO2 nanocubes with exposed {100} facets exhibit a higher peroxidase but lower superoxide dismutase activity than those of the CeO2 nanorods with exposed {110} facets. Our results provide new insights into the redox enzyme-mimicking activities of CeO2 nanostructures, as well as the design and synthesis of inorganic nanomaterials-based artificial enzymes.

Synthesis of CeO2 nanoparticles with different morphologies and their properties as peroxidase mimic

“…Meanwhile, both surface oxygen and lattice oxygen show oxidation in CeO 2 nanoparticles. It has been found that CeO 2 nanoparticles can display the properties of catalase, oxidase, and superoxide dismutase . Based on this, CeO 2 nanoparticles have been used for the determination of glucose and nucleic acid.…”

“…Due to the valence of cerium element can be reciprocally transformed in trivalent and tetravalent, CeO 2 nanoparticles can act as catalysts in many reactions, such as photodegradation of organic pollutants, water splitting, oxidation reduction reaction in organic synthesis . Meanwhile, both surface oxygen and lattice oxygen show oxidation in CeO 2 nanoparticles.…”

Ceria Nanoparticles as Enzyme Mimetics

“…This study demonstrated a clear plane-dependent reduction shell at the surface of nanoceria and provided a direct explanation for the observed lower catalytic activity of the (111) surfaces with respect to the (100) surfaces. More recently, Yang et al [100] found that cubic nanoceria with exposed (100) planes exhibited a higher peroxidase but lower SOD mimetic activity than the rod-like nanoceria with exposed (110) planes. Therefore, selection of exposed planes could affect the catalytic efficiency of nanoceria-based enzyme mimetics.…”

Synthesis of CeO2-based core/shell nanoparticles with high oxygen storage capacity

“…2b, d, f were used. The inter-planar distance of 0.31 nm corresponds to (111) plane of the fluorite-type CeO 2 structure [19]. The inter-planar distance values of 0.29, 0.35, and 0.25 nm are associated with ZrO 2 (111) [20], TiO 2 (101) [21], and CuO (002) [22] planes, respectively.…”