A Novel Electrochemical Sensor Based on a Cerium Oxide/Gold/Carbon Nanocomposite for the Detection of Hydroxyl Free Radicals

Abstract

Hydroxyl radicals (•OH) are well known as crucial chemicals for maintaining the normal activities of human cells; however, the excessive concentration of •OH disrupts their normal function, causing various diseases, including liver and heart diseases, cancers, and neurological disorders. The detection of •OH as a biomarker is thus essential for the early diagnosis of these serious conditions. Herein, a novel electrochemical sensor comprising a composite of cerium oxide nanoclusters, gold nanoparticles, and a highly conductive carbon was developed for detecting •OH. Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) were employed to characterize the signals generated by the interaction of the composite with •OH radicals. The CV results revealed that the developed sensor could accurately and selectively detect •OH in the Fenton reaction. The sensor demonstrated a linear relationship between the current peak and •OH concentration in the range 0.05 − 0.5 mM and 0.5 − 5 mM with a limit of detection (LOD) of 58 μ M. In addition, EIS studies indicated that this electrochemical sensor could distinguish between •OH and similar reactive oxygen species (ROS), like hydrogen peroxide (H 2 O 2 ). It is also worth mentioning that additional merits, such as reproducibility, repeatability, and stability of the sensor were confirmed.