Electrochemical Detection and Sensing of Reactive Oxygen Species

Abstract

Reactive oxygen species (ROS) such as superoxide anion radical (O2 -⋅ ) play an essential role on normal cellular growth and homeostasis. However, excess ROS generated by perturbing O2 -⋅ homeostasis under various conditions of oxidative stress induce high radical toxicity, resulting in many diseases such as cancer, brain and myocardial infarction, and inflammation. Quantitative analysis of O2 -⋅ by a convenient method is a subject of intense research, since most of ROS are derived from O2 -⋅ . In situ real-time measurement of O2 -⋅ is very important to understand the relevance of ROS to many diseases. Recent progress in electrochemical sensors for the facile detection of O2 -⋅ , including biosensors utilizing a variety of metalloproteins as sensing elements for O2 -⋅ and very recently developed all-synthetic sensors with a high selectivity for O2 -⋅ detection, is reviewed. Emphasis is placed on the possibility of the all-synthetic sensor for convenient in vivo measurement of ROS.

A Reactive Oxygen/ZNitrogen Species Sensor Fabricated from an Electrode Modified with a Polymerized Iron Porphyrin and a Polymer Electrolyte Membrane

“…19 The O2 -• sensor was fabricated by the electropolymerization of FeT3ThP on a glassy carbon electrode (GCE), and in vivo quantitative measurement of O2 -• was successful using this electrode. [19][20][21] We also investigated the electrochemical detection of NO as an outbreak factor of various diseases using the poly(FeT3ThP)-modified (FePor-modified) electrode, thus validating our device as an ROS/RNS sensor. In addition, the electrode surface of the sensor was coated with a polymer electrolyte membrane to improve its selectivity for NO detection.…”

“…19,20 Briefly, a 0.1 M solution of tetrabutylammonium perchlorate (TBAP) in dichloromethane containing 50 mM FeT3ThP and 250 mM 1-methyl imidazole as an axial ligand for the porphyrin was prepared as a monomer solution for electropolymerization. FePor was formed on a plastic formed carbon (PFC) working electrode (0.3 mm in diameter) of an integrated electrode, which consisted of the PFC electrode coated with an insulating cellulose layer on the side, which was placed in a 18-G stainless steel needle counter electrode.…”

“…Electropolymerization was performed in a two-chamber threeelectrode electrochemical cell with a stainless steel (SUS 304) electrode and Ag/Ag + electrodes as the counter and reference electrodes, respectively, by potential cycling from 0 to +2.0 V vs. Ag/Ag + at a potential sweep rate of 50 mV s -1 using a potentiostat (HZ-5000, Hokuto Denko). [19][20][21] After rinsing with dichloromethane, the FePor-modified electrode was obtained.…”

“…[19][20][21] XAN and XOD were purchased from Wako and Sigma-Aldrich, respectively. A 0.1 mM XAN-containing 0.15 M phosphate buffered saline (PBS) mixture was pumped through an electrochemical flow cell at a flow rate of 1.0 mL min -1 , and the amperometric current was recorded with a two-electrode system at a potential of +0.5 V vs. stainless steel (SUS 304).…”

“…2), indicating the presence of iron porphyrins, as described in our previous reports. 19,20 Electrochemical detection of O2 -• at the FePor-modified electrode sensor was investigated using a XAN/XOD system for in situ O2 -• generation. The amperometric current response (∆I) increases as the XOD concentration, and thus the O2 -• concentration, increases (Fig.…”