Polymerized hemin as an electrocatalytic platform for peroxynitrite's oxidation and detection

Abstract

Peroxynitrite (ONOO(-)) constitutes a major cytotoxic agent, implicated in a host of pathophysiological conditions, thereby stimulating a tremendous interest in evaluating its role as an oxidant in vivo. Some of the detection methods for peroxynitrite include oxidation of fluorescent probes, EPR spectroscopy, chemiluminescence, immunohistochemistry, and probe nitration; however, these are more difficult to apply for real-time quantification due to their inherent complexity. The electrochemical detection of peroxynitrite is a simpler and more convenient technique, but the best of our knowledge there are only few papers to date studying its electrochemical signature, or reporting amperometric microsensors for peroxynitrite. Recently, we have reported the use of layered composite films of poly(3,4-ethylenedioxythiophene) (PEDOT) and hemin (iron protoporphyrin IX) as a platform for amperometric measurement of peroxynitrite. The main goal herein is to investigate the intrinsic catalytic role of hemin electropolymerized thin films on carbon electrodes in oxidative detection of peroxynitrite. The electrocatalytic oxidation of peroxynitrite is characterized by cyclic voltammetry. The catalytic current increased as a function of peroxynitrite's concentration, with a peak potential shifting positively with peroxynitrite's concentration. The catalytic efficiency decreased as the scan rate increased, and the peak potential of the catalytic oxidation was found to depend on pH. We show that optimized hemin-functionalized carbon electrodes can be used as simple platforms for peroxinitrite detection and quantification. We report dose-response amperometry as an electroanalytical determination of this analyte on hemin films and we contrast the intrinsic hemin catalytic role with its performance in the case of the PEDOT-hemin as a composite matrix. Finally, we include some work extending the use of simple hemin films for peroxynitrite determination on carbon microfiber electrodes in a flow system.

Chemical Effects of Air Plasma Species on Aqueous Solutes in Direct and Delayed Exposure Modes: Discharge, Post-discharge and Plasma Activated Water

“…Peteu's group [89] reported using electrochemical measurements of electropolymerized hemin on graphite electrodes and proposed using the electrode for measuring peroxynitrite concentrations.…”

Electrochemical detection of peroxynitrite using hemin–PEDOT functionalized boron-doped diamond microelectrode

“…Previous studies [25] examined the ratio I/I 0 ; that is the peak current of the voltammetric wave of the modified electrode in the presence of PON (I) relative to the current measured in absence of the analyte at same potential ( I 0 ). The I/I 0 depends on the scan rate and gradually decreases as the scan rate increased for all concentrations studied [25,26]. This behavior is typical of an electrocatalytic process [67] where the oxidation of PON is mediated by the hemin polymeric film.…”

“…vs. Ag/AgCl under a N 2 gas blanket. The hemin-PEDOT film is formed by electropolymerization with the hemin molecules incorporated into the PEDOT network as shown in Figure 3A [25,26,49]. The oxidized conductive polymer turns back into a neutral (undoped) semiconductive form upon reduction.…”

Meat Freshness: Peroxynitrite’s Oxidative Role, Its Natural Scavengers, and New Measuring Tools

“…The analyte tests indicated a fast catalytic oxidation of PON specific for hemin, and not for protoporphyrin-only films where iron was absent.This finding suggests a fundamental role of the bound iron center atom to ensure the oxidative catalytic turnover of PON (Q). In separate tests, related species such as NO•, nitrite, or nitrate did not interfere with electrocatalytic detection of PON (138).…”

“…In a follow up investigation, Peteu and colleagues electro-polymerized hemin thin films on either GCEs or C μFEs (138) and assessed the resulting sensors' oxidative detection of PON in stirred solution or in a flow-cell. The advantages of using a flow-cell include the convective transport of analyte, resulting in less noise and faster response times.…”