Intrinsic Enzyme-like Activities of Cerium Oxide Nanocomposite and Its Application for Extracellular H2O2 Detection Using an Electrochemical Microfluidic Device

Negar Alizadeh; Abdollah Salimi; Tsun-Kong Sham; Paul Bazylewski; Giovanni Fanchini

doi:10.1021/acsomega.9b03252

Intrinsic Enzyme-like Activities of Cerium Oxide Nanocomposite and Its Application for Extracellular H₂O₂ Detection Using an Electrochemical Microfluidic Device

ACS Omega. 2020 May 19;5(21):11883-11894. doi: 10.1021/acsomega.9b03252. eCollection 2020 Jun 2.

Authors

Negar Alizadeh¹, Abdollah Salimi^{1

2

3}, Tsun-Kong Sham², Paul Bazylewski⁴, Giovanni Fanchini⁴

Affiliations

¹ Department of Chemistry, University of Kurdistan, 66177-15175 Sanandaj, Iran.
² Department of Chemistry, University of Western Ontario, 1151 Richmond St., N6A 5B7 London, Ontario, Canada.
³ Research Center for Nanotechnology, University of Kurdistan, 66177-15175 Sanandaj, Iran.
⁴ Department of Physics and Astronomy, University of Western Ontario, 1151 Richmond St., N6A 3K7 London, Canada.

Abstract

Artificial enzyme mimics have gained considerable attention for use in sensing applications due to their high stability and outstanding catalytic activity. We show that cerium oxide nanosheets (NSs) exhibit triple-enzyme mimetic activity. The oxidase-, peroxidase-, and catalase-like activities of the proposed nanoparticles are demonstrated using both colorimetric and electron paramagnetic resonance (EPR) spectroscopy. On the basis of the excellent catalytic activity of cerium oxide NSs toward hydrogen peroxide, an electrochemical approach for the high-throughput detection of H₂O₂ in living cells was established. This report presents an analytical microfluidic chip integrated with a cerium oxide NS mimic enzyme for the fabrication of a simple, sensitive, and low-cost electrochemical sensor. Three Au microelectrodes were fabricated on a glass substrate using photolithography, and the working electrode was functionalized using cerium oxide NSs. The operation of this biosensor is based on cerium oxide NSs and presents a high sensitivity over a wide detection range, between 100 nM and 20 mM, with a low detection limit of 20 nM and a high sensitivity threshold of 226.4 μA·cm^-2·μM^-1. This microfluidic sensor shows a strong response to H₂O₂, suggesting potential applications in monitoring H₂O₂ directly secreted from living cells. This sensor chip provides a promising platform for applications in the field of diagnostics and sensing.