Disposable Amperometric Sensor for Neurotransmitters Based on Screen-Printed Electrodes Modified with a Thin Iridium Oxide Film

Abstract

Adrenaline and dopamine are very important catecholamine neurotransmitters in the mammalian central nervous system. Catecholamine drugs are also used to treat hypertension, bronchial asthma and organic heart disease, and are used in cardiac surgery and myocardial infraction. [1][2][3][4] The determination of catecholamines and their metabolites in body fluids, such as urine, plasma and serum, is one of the most important ways to evaluate the activity of the sympathetic nervous system and support the diagnosis of many diseases in fields of clinical medicine. Several highperformance liquid chromatography (HPLC) methods with online purification have been described for use in the analysis of catecholamines in biological samples using either fluorescence detection, [5][6][7] on-line chemical derivatization followed by fluorescence detection, [8][9][10][11] capillary electrophoresis 12,13 or flow injection analysis. 14,15 These methods generally have good sensitivity and reproducibility, and can meet practical requirements, but require expensive instruments, a well-controlled experimental condition and profound sample making. Therefore, simple methods are expected and attention has been paid to them. Electrochemical detection offers several advantages, including remarkable sensitivity, inherent minituralization and portability, independence of the optical path length or sample turbidity, low cost, low power requirements and high compatibility with advanced micromachining technologies. Because of the simple procedure and high sensitivity of electroanalysis and the electroactivity of catecholamines, studying and measuring catecholamines with electrochemical methods were carried out. HPLC coupled with electrochemical detection has been used for simultaneously measuring catecholamines. [16][17][18] In most of these applications, the use of bare electrodes for the electrochemical detection of catecholamines has a number of limitations, such as low sensitivity and reproducibility, a slow electron-transfer reaction, low stability over a wide range of solution composition and a high overpotential, at which the electron transfer process occurs. In order to maintain the stability of the electrode responses and also to improve the analytical characteristics of the detection of substrates, a chemical modification or electrochemical pretreatments should be applied to the working electrode.Gold electrodes modified with a self-assembled monolayer of 3-mercaptopropionic acid, 19 a glassy carbon electrode modified with cobalt(II) hexacyanoferrate films, 20 a glassy carbon electrodes modified with multiwall carbon nanotubes, 21 Pt and GC electrode modified with electropolymerization of luminal, 22 a L-cysteine self-assembled monolayer modified gold electrode, 23 a glassy carbon electrode modified with C60-dimethyl(β-cyclodextrine)2, 24 and a polyisonicotinic acid modified glassy carbon electrode, 25 have been used for the determination of catecholamines. Unfortunately, most modified electrodes used for catecholamines detection have cer...

Synthesis of Iridium Oxide Nanotubes by Electrodeposition into Polycarbonate Template: Fabrication of Chromium(III) and Arsenic(III) Electrochemical Sensor

“…Owing to the low costs, easy operation and high sensitivity, electrocatalysis through different redox mediation is an attractive technique for routine Cr 3+ and As 3+ analysis. Because of electrochemical reversibility and high electron transfer rate constant of the Ir(III)/Ir(IV) redox couple at wide pH range, it can be used as mediator for shuttle electrons between electrodes and analytes 47–54. In order to evaluate the electrocatalytic ability of the IrO x nanotube modified electrode toward oxidation of Cr 3+ and As 3+ cyclic voltammograms of the modified and unmodified electrodes were obtained in the presence and absence of the proposed analytes in the pH 5 buffer solution.…”

“…In addition, IrO 2 has also been studied as a high performance field emitter through its low work function, low resistivity and excellent stability against oxygen 45, 46. Due to reversible faradic reactions for the Ir 3+ /Ir 4+ redox couple in a wide pH range, the IrO 2 based modified electrodes have been used for pH sensing, electrocatalytic reactions and electroanalysis 47–54.The synthesis of IrO 2 nanorods and their practical applications has been reported 55–57.…”

pH electrodes based on iridium oxide films for marine monitoring

“…During electrodeposition, it is necessary to adjust the pH value of the electrodeposition solution, control the potential sweep range during deposition, and select the appropriate deposition time [13,28,29]. Common electrochemical deposition methods are listed in Table 1, which mainly include continuous current deposition [30,31], pulse voltage deposition [32], potential scanning, and cyclic voltammetry (CV) [33,34].…”

Simultaneous Determination of Dopamine in the Presence of Ascorbic Acid and Uric Acid by Electrochemically Oxidized Screen Printed Carbon Electrode

“…However, the use of the SPPEs for simultaneous determination of AA, DA and UA has rarely been reported, since the unmodified SPCEs are unable to discriminate signals of AA, DA, and UA. Several works dealt with SPCE to improve selective detection of DA in the presence of AA and UA by coating the surface of SPCE with sulfonic acid-polyaniline nanoparticles [18], iridium oxide [19]. However, sensitivity and reproducibility of these electrodes are very poor, and the fabrication process is complex.…”