Peroxynitrite Electrochemical Signature on Selenium and Selenium-Decorated Graphene Depositions

Reactive oxygen species (ROS) such as peroxynitrite have been linked to oxidative stress-induced diseases such as cardiovascular failure. Determining the cause and progression of such disease, as well as testing the efficacy of potential treatments all hinge on the ability to accurately detect these species in biological systems. Antioxidant uses of selenium have garnered the attention of scientists in recent years. Latest investigations have revealed that selenium is essential for redox regulation as a ROS modulator and as a catalytic cofactor of endogenous antioxidative mechanisms. The advantages of preparing selenium electrochemical depositions as sensitive surfaces for peroxynitrite detection and quantification were revealed in our research. Electrochemical sensors with high sensitivity and selectivity were developed by dissolving selenium dioxide in an acidic medium. Graphene nanostructures loaded with selenium were used to modify one set of glassy carbon electrodes (GCEs), while selenium nanoparticles were used to modify another set of GCEs for comparison purposes. The shape and surface chemistry of selenium and selenium-decorated graphene nanostructures were investigated using scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX). The electrochemical catalytic activity of these systems was determined using cyclic voltammetry and chronoamperometry. The thickness of the deposited selenium interfaces was measured using Quartz Crystal Microbalance (QCM) analysis. Elemental selenium nanoparticles showed an increase in the sensitivity toward peroxynitrite when embedded into graphene sheets. In addition, it allowed for the use of low positive potential, leading to improved segregation of peroxynitrite from other analytes that are sensitive to higher potentials.