The Preparation Temperature Influences the Physicochemical Nature and Activity of Nanoceria

Robert A. Yokel, Wendel Wohlleben, Johannes Georg Keller, Matthew L. Hancock, Jason M. Unrine, D. Allan Butterfield, Eric A. Grulke

Research output: Contribution to journalArticlepeer-review

Abstract

Cerium oxide nanoparticles, so-called nanoceria, are engineered nanomaterials prepared by many methods that result in products with varying physicochemical properties and applications. Those used industrially are often calcined, an example is NM-212. Other nanoceria have beneficial pharmaceutical properties and are often prepared by solvothermal synthesis. Solvothermally synthesized nanoceria dissolve in acidic environments, accelerated by carboxylic acids. NM-212 dissolution has been reported to be minimal. To gain insight into the role of high-temperature exposure on nanoceria dissolution, product susceptibility to carboxylic acid-accelerated dissolution, and its effect on biological and catalytic properties of nanoceria, the dissolution of NM-212, a solvothermally synthesized nanoceria material, and a calcined form of the solvothermally synthesized nanoceria material (ca. 40, 4, and 40 nm diameter, respectively) was investigated. Two dissolution methods were employed. Dissolution of NM-212 and the calcined nanoceria was much slower than that of the non-calcined form. The decreased solubility was attributed to an increased amount of surface Ce4+species induced by the high temperature. Carboxylic acids doubled the very low dissolution rate of NM-212. Nanoceria dissolution releases Ce3+ions, which, with phosphate, form insoluble cerium phosphate in vivo. The addition of immobilized phosphates did not accelerate nanoceria dissolution, suggesting that the Ce3+ion release during nanoceria dissolution was phosphate-independent. Smaller particles resulting from partial nanoceria dissolution led to less cellular protein carbonyl formation, attributed to an increased amount of surface Ce3+species. Surface reactivity was greater for the solvothermally synthesized nanoceria, which had more Ce3+species at the surface. The results show that temperature treatment of nanoceria can produce significant differences in solubility and surface cerium valence, which affect the biological and catalytic properties of nanoceria.

Original languageEnglish
Pages (from-to)525-540
Number of pages16
JournalBeilstein Journal of Nanotechnology
Volume12
DOIs
StatePublished - 2021

Bibliographical note

Funding Information:
The authors gratefully acknowledge Marsha L. Ensor, Shristi Shrestha, and Shekinah Alfaro for their excellent contributions to this research.

Funding Information:
The research leading to these results received funding from the National Institutes of Health [grant agreement No R01GM109195] and the PATROLS project, as part of European Union’s Horizon 2020 research and innovation program [grant agreement No 760813]. The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health.

Publisher Copyright:
© 2021 Yokel et al.; licensee Beilstein-Institut. License and terms: see end of document.

Keywords

  • cerium
  • dissolution
  • nanoparticles
  • physicochemical properties
  • valence state

ASJC Scopus subject areas

  • Materials Science (all)
  • Physics and Astronomy (all)
  • Electrical and Electronic Engineering

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