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Science & Technology

February 16, 2009
Volume 87, Number 07
p. 41

Science & Technology Concentrates

Ceria Nanoparticles Act Like Enzymes

Polymer-coated cerium oxide nanoparticles exhibit oxidase-like activity at low pH without the need for hydrogen peroxide as an oxidizing agent

Stephen K. Ritter


Polymer-coated cerium oxide nanoparticles exhibit unique oxidase-like activity at low pH without the need for hydrogen peroxide as an oxidizing agent, a finding that could lead to simpler and less expensive immunoassays (Angew. Chem. Int. Ed., DOI: 10.1002/anie.200805279). The nanoparticles created by Atul Asati, J. Manuel Perez, and coworkers at the University of Central Florida's Nanoscience Technology Center are robust aqueous redox catalysts. The team tested the oxidizing capability of the nanoparticles on 3,3′,5,5′-tetramethylbenzidine (TMB) and 2,2-azinobis(3-ethylbenzothizoline-6-sulfonic acid) (AzBTS), which are dyes that undergo a color change when oxidized and are commonly used in horseradish peroxidase-based bioassays. These assays usually require H2O2 as an oxidant to work in conjunction with the enzyme, but the ceria nanoparticles work well at pH 4 without H2O2. Inspired by their success, the researchers added folic acid groups to the surface of poly(acrylic acid)-coated ceria nanoparticles, enabling them to bind to folate receptors, which are overexpressed in many types of cancer cells. When the folate-modified nanoparticles were combined with lung cancer cells and subsequently incubated with TMB, the team saw a color change associated with TMB oxidation, indicating a positive test for the cancer cells.

Polymer-coated 
ceria nanoparticles readily oxidize  
colorimetric dyes in aqueous solution. Angew. Chem. Int. Ed.
Clever Kicker Polymer-coated ceria nanoparticles readily oxidize colorimetric dyes in aqueous solution.

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Polymer-coated cerium oxide nanoparticles exhibit oxidase-like activity at low pH without the need for hydrogen peroxide as an oxidizing agent.

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Chemical & Engineering News
ISSN 0009-2347
Copyright © 2011 American Chemical Society