Amperometric Nitric Oxide Sensor Based on Poly(Thionine)/Nafion‐Modified Electrode and Its Application in Monitoring Nitric Oxide Release from Rat Kidney

Abstract

A novel amperometric nitric oxide (NO) sensor based on a glassy carbon electrode modified with thionine and Nafion films has been developed. The oxidation peak current of NO increased significantly at the poly(thionine)/Nafion‐modified glassy carbon electrode (GCE), which can be used for the detection of NO. The oxidation peak current was linear with the concentration of nitric oxide over the range from 3.6×10^?7 to 6.8×10^?5 mol · L^?1, and the detection limit was 7.2×10^?8 mol · L^?1. This nitric oxide sensor showed high selectivity to nitric oxide determination, and some potential interference could be eliminated effectively. The nitric oxide sensor has been applied to monitor NO release from rat kidney stimulated by L‐arginine. The results indicated the applicability of the NO sensor to biomedical samples.     

Highly Sensitive Electrochemical Sensor for Nitric Oxide Using the Self‐Assembled Monolayer of 1,8,15,22‐Tetraaminophthalocyanatocobalt(II) on Glassy Carbon Electrode

Glassy carbon (GC) electrode modified with a self‐assembled monolayer (SAM) of 1,8,15,22‐tetraaminophthalocyanatocobalt(II) (4α‐Co^IITAPc) was used for the selective and highly sensitive determination of nitric oxide (NO). The SAM of 4α‐Co^IITAPc was formed on GC electrode by spontaneous adsorption from DMF containing 1 mM 4α‐Co^IITAPc. The SAM showed two pairs of well‐defined redox peaks corresponding to Co^III/Co^II and Co^IIIPc^?1/Co^IIIPc^?2 in 0.2 M phosphate buffer (PB) solution (pH 2.5). The SAM modified electrode showed excellent electrocatalytic activity towards the oxidation of nitric oxide (NO) by enhancing its oxidation current with 310 mV less positive potential shift when compared to bare GC electrode. In amperometric measurements, the current response for NO oxidation was linearly increased in the concentration range of 3×10^?9 to 30×10^?9 M with a detection limit of 1.4×10^?10 M (S/N=3). The proposed method showed a better recovery for NO in human blood serum samples.     

Planar nitric oxide (NO)-selective ultramicroelectrode sensor for measuring localized NO surface concentrations at xerogel microarrays

A planar ultramicroelectrode nitric oxide (NO) sensor was fabricated to measure the local NO surface concentrations from NO-releasing microarrays of varying geometries. The sensor consisted of platinized Pt (25 microm) working electrode and a silver paint reference electrode coated with a thin silicone rubber gas permeable membrane. An internal hydrogel layer separated the Pt working electrode and gas permeable membrane. The total diameter of the sensor was 相似文献   

Nitric oxide measurement in biological and pharmaceutical samples by an electrochemical sensor

A nitric oxide (NO) electrochemical sensor was developed via one-step construction of gold nanoparticles (GNPs)–chitosan (CS) nanocomposite sensing film on a glassy carbon electrode (GCE) surface. This method is very simple and convenient. The GNPs–CS film which is controllable and stable exhibits catalytic activity to NO oxidation. The anodic peak potential significantly shifted negatively compared with that at bare GCE. The high sensitivity and good stability of developed method have been coupled to a wide linear range from 3.60 × 10⁻⁸ to 4.32 × 10⁻⁵ M for the quantitative analysis of NO. The detection limit of 7.20 nM is much lower than the vast majority of reported methods. This NO sensor has been successfully applied to NO measurement in biological and pharmaceutical samples. Real-time amperometric data show that the addition of L-arginine (L-Arg) can cause a slow release of NO from a whole rat kidney with a maximum concentration of ca. 150 nM. The concentration of NO monitoring from the drug sample was calculated to be ca. 1.60 μM.     

Flow injection measurements of <Emphasis Type="Italic">S</Emphasis>-nitrosothiols species in biological samples using amperometric nitric oxide sensor and soluble organoselenium catalyst reagent

A novel flow injection analysis (FIA) system suitable for measurement of S-nitrosothiols (RSNOs) in blood plasma is described. In the proposed (FIA) system, samples and standards containing RSNO species are injected into a buffer carrier stream that is mixed with the reagent stream containing 3,3′-dipropionicdiselenide (SeDPA) and glutathione (GSH). SeDPA has been shown previously to catalytically decompose RSNOs in the presence of a reducing agent, such as GSH, to produce nitric oxide (NO). The liberated NO is then detected downstream by an amperometric NO sensor. This sensor is prepared using an electropolymerized m-phenylenediamine (m-PD)/resorcinol and Nafion composite films at the surface of a platinum electrode. Using optimized flow rates and reagent concentrations, detection of various RSNOs at levels in the range of 0.25–20 μM is possible. For plasma samples, detection of background sensor interference levels within the samples must first be carried out using an identical FIA arrangement, but without the added SeDPA and GSH reagents. Subtraction of this background sensor current response allows good analytical recovery of RSNOs spiked into animal plasma samples, with recoveries in the range of 90.4–101.0%.     

Electrocatalytic Oxidation of Nitric Oxide on an Electrode Modified with Fullerene Films

Fullerene was immobilized on the surface of a glassy carbon electrode and reduced by an electrochemical method to form a partially reduced fullerene film. The films on the electrode showed stable electrocatalytic activity towards the oxidation of nitric oxide (NO). The catalytic current was proportional to the concentration of nitric oxide. Based on this property, a method for the detection of nitric oxide in aqueous solution is proposed. The detection conditions, such as supporting electrolyte, scan rate and thickness of the film were optimized. Under the optimized conditions, the catalytic currents increase linearly with the concentration of NO in the range of 3×10^–71.0×10^–4M, and the detection limit is 7.4×10^–8M. In addition, the modified electrode is very selective with respect to interferences including ascorbic acid, dopamine, and nitrite when further modified by a Nafion film on the surface of the electrode. The experimental results indicate that the partially reduced fullerene can act as an NO sensor featuring fast response and high stability.     

Electrochemical Detection of Para‐nitrophenol using Copper Metal Nanoparticles Modified Gold Electrode

para‐Nitrophenol (p‐NP) is a high priority environmental pollutant. For the sake of safety, sensitive detection of its presence in water resources and food is highly important. The present article describes the use of copper metal nanoparticles for selective and sensitive electrochemical detection of p‐NP in pure and real sample. For this the gold electrode was fabricated by polyvenylpyrrolidone stabilized copper metal nanoparticles (ca . 4 nm d.) via self‐assembled 4,4′‐bipyridine monolayer and characterized by microscopic and electrochemical techniques. The newly developed sensor permits for sensitive detection of p‐NP in a linear concentration range of 1–500 μM with lowest detection limit of 0.34 nM and high sensitivities 247.1 μA cm⁻² μM⁻¹. The sensor electrode exhibited high stability, reproducibility, good selectivity in the presence of potential interfering agents and had an excellent capability for the selective determination of p‐NP in river water without preliminary treatments.     

Functionalization of Reduced Graphene Oxide with β‐cyclodextrin Modified Palladium Nanoparticles for the Detection of Hydrazine in Environmental Water Samples

A sensitive and selective hydrazine sensor was developed by β‐cyclodextrin modified palladium nanoparticles decorated reduced graphene oxide (PdNPs‐β‐CD/rGO) nanocomposite. The PdNPs‐β‐CD/rGO hybrid material was prepared by simple electrochemical method. The hydrophobic cavity of β‐CD ineracts with palladium nanoparticles by hydrophobic interaction and further it is uniformly assembled on the rGO surface through hydrogen bond formation, which is clearly confirmed by FT‐IR, FESEM and TEM. The high electrocatalytic activity of hydrazine oxidation was observed at −0.05 V (vs. Ag/AgCl) on PdNPs‐β‐CD/rGO modified electrode; due to the excellent stabilization, high catalytic activity and large surface area of the PdNPs‐β‐CD/rGO composite. The PdNPs‐β‐CD/rGO fabricated hydrazine sensor exhibited an excellent analytical performance, including high sensitivity (1.95 μA μM⁻¹ cm⁻²), lower detection limit (28 nM) and a wide linear range (0.05 to 1600 μM). We also demonstrated that the PdNPs‐β‐CD/rGO nanocomposite modified electrode is a highly selective and sensitive sensor towards detection of hydrazine among the various interfering species. Hence, the proposed hydrazine sensor is able to determine hydrazine in different water samples.     

Highly Sensitive Nitric Oxide Sensing Using Three‐Dimensional Graphene/Ionic Liquid Nanocomposite

A nanocomposite gel with a uniform porous structure and well‐controlled compositions prepared by mixing three‐dimensional graphene material with an ionic liquid, 1‐butyl‐3‐methylimidazolium hexafluorophosphate, is used for nitric oxide detection. It shows a fast response of less than 4 seconds, an excellent sensitivity of 11.2 µA cm⁻² (µmol/L)⁻¹ and an extremely low detection limit of 16 nM with a signal‐to‐noise ratio of 3 (S/N=3), a performance superior to that of reported works based on carbon nanotubes and nanoparticles. The high sensitivity is attributed to the large electroactive surface area of the graphene gel nanocomposite towards nitric oxide oxidation. The electrochemical behavior of the gel nanocomposite is investigated and explained.     

Electrocatalytic oxidation of nitric oxide at nano-TiO2/Nafion composite film modified glassy carbon electrode

A novel nanocrystalline TiO₂ (nano-TiO₂) and Nafion composite film modified glassy carbon electrode has been developed for the determination of nitric oxide (NO) radical in an aqueous solution. This modified electrode can be employed as a NO sensor with a low detection limit, fast response, high sensitivity and selectivity. Two apparent anodic peaks were observed at 0.67 and 0.95 V at the nano-TiO₂ modified glassy carbon electrode by differential pulse voltammetry (DPV). After further modification with a thin film of Nafion, which was capable of preventing some anionic interference such as nitrite and ascorbic acid, only one peak appeared and the peak current enhanced greatly. The chronocoulometric experimental results showed NO was oxidized by one-electron transfer reaction at the composite film modified electrode. The amperometric responses increased linearly with the concentrations of NO ranging from 3.6×10⁻⁷ mol/L to 5.4×10⁻⁵ mol/L. The detection limit was estimated to be 5.4×10⁻⁸ mol/L. In this sensor system, the modification film provides complete selectivity for NO over nitrite anions (NO₂⁻).     

Direct Electrochemistry of Myoglobin on a Room Temperature Ionic Liquid Modified Electrode and Its Application to Nitric Oxide Biosensing

Myoglobin (Myb) was successfully immobilized on a room temperature ionic liquid (RTIL), 1‐ethyl‐3‐methyl imidazolium tetrafluoroborate ([EMIM][BF₄]) modified basal plane graphite (BPG) electrode. The electrochemical behavior of Myb on RTIL modified BPG electrode was explored and the results from cyclic voltammetry (CV) showed a well‐defined and quasi‐reversible CV peaks with a formal potential of ?0.379 V (versus Ag/AgCl) in a phosphate buffer solution (pH 7.0). RTIL shows an obvious promotion for the direct electron‐transfer between Myb and BPG electrode. Myb adsorbed on electrode surface exhibits an obvious electrocatalytic activity for the reduction of nitric oxide (NO). The catalytic current is corresponding linearly to the NO concentration in the range of 7.0×10^?7 to 7.0×10^?6 M with a limit of detection of 2.0×10^?7 M (three times the ratio of signal to noise, S/N=3).     

Microfluidic Device Using a Gold Pillar Array and Integrated Electrodes for On‐chip Endothelial Cell Immobilization,Direct RBC Contact,and Amperometric Detection of Nitric Oxide

We describe a microfluidic device that can be used to detect interactions between red blood cells (RBCs) and endothelial cells using a gold pillar array (created by electrodeposition) and an integrated detection electrode. Endothelial cells can release nitric oxide (NO) via stimulation by RBC‐derived ATP. These studies incorporate on‐chip endothelial cell immobilization, direct RBC contact, and detection of NO in a single microfluidic device. In order to study the RBC‐EC interactions, this work used a microfluidic device made of a PDMS chip with two adjacent channels and a polystyrene base with embedded electrodes for creating a membrane (via gold pillars) and detecting NO (at a glassy carbon electrode coated with platinum‐black and Nafion). RBCs were pharmacologically treated with treprostinil in the absence and presence of glybenclamide, and ATP release was determined as was the resultant NO release from endothelial cells. Treprostinil treatment of RBCs resulted in ATP release that stimulated endothelial cells to release on average 1.8±0.2 nM NO per endothelial cell (average±SEM, n=8). Pretreatment of RBCs with glybenclamide inhibited treprostinil‐induced ATP release and, therefore, less NO was produced by the endothelial cells (0.92±0.1 nM NO per endothelial cell, n=7). In the future, this device can be used to study interactions between many other cell types (both adherent and non‐adherent cell lines) and incorporate other detection schemes.     

Electrochemical Properties of Ag@iron Oxide Nanocomposite for Application as Nitrate Sensor

Ag@iron oxide nanocomposite powders were synthesized via a two‐step chemical method. Characterization by UV‐Vis, XRD, SEM‐EDX and TEM revealed they are composed of nanosized crystalline silver particles in strict contact with amorphous iron oxide(s). The electrochemical behavior of the synthesized Ag@iron oxide composite was investigated by cyclic voltammetry. Compared with the single phase‐modified electrodes, the Ag@iron oxide/SPCE electrode exhibits an enhanced cathodic current in response to the target analyte, due to a synergistic effect between Ag crystallites and amorphous iron oxide nanoparticles. An amperometric sensor for detection of nitrate based on Ag@iron oxide modified screen‐printed electrode (Ag@iron oxide/SPCE) has been fabricated, showing a good sensitivity (663 µA mM^?1 cm^?2) and a detection limit of 30 µM.     

A novel copper(Ⅱ) complex-based fluorescence probe for nitric oxide detecting and imaging

A novel copper(II) complex CuQNE with a naphthalimide-containing ligand was synthesized as a fluorescent sensor of nitric oxide (NO). It featured eightfold fluorescent enhancement toward NO from a dark-background with the detection limit of NO about 1 nM in aqueous solution. The fluorescence response of the CuQNE was specific for NO, the presence of other reactive oxygen species (ROS) and reactive nitrogen species (RNS) did not interfere with the detection of NO in aqueous solution. LC–MS and IR spectra of the reaction mixture both demonstrated that the fluorescence enhancement was possibly attributed to an NO-induced nitrosation of the amino group. Confocal fluorescence images of MCF-7 cells suggested that CuQNE could be applied for monitoring intracellular NO.     

Glutathione Peroxidase‐Based Amperometric Biosensor for the Detection of S‐Nitrosothiols

A new biosensor is described for the detection of S‐nitrosothiols (RSNOs) based on their decomposition by immobilized glutathione peroxidase (GPx), an enzyme containing selenocysteine residue that catalytically produces nitric oxide (NO) from RSNOs. The enzyme is entrapped at the distal tip of a planar amperometric NO sensor. The new biosensor shows good sensitivity, linearity, reversibility, and response times towards various RSNO species in PBS buffer, pH 7.4 . In most cases, the response time is less than 5 min, and the response is linear up to 6 μM of the tested RSNO species. The lowest detection limit is obtained for S‐nitrosocysteine (CysNO), at approx. 0.2 μM. The biosensor's sensitivity is not affected by the addition of EDTA as a chelating agent; an advantage over other potential catalytic enzymes that contain copper ion centers, such as CuZn‐superoxide dismutase and xanthine oxidase. However, lifetime of the new sensor is limited, with sensitivity decrease of 50% after two days of use. Nonetheless, the new amperometric GPx based RSNO sensor could prove useful for detecting relative RSNO levels in biological samples, including whole blood.     

An Amperometric Biological Toxic Hydrazine Sensor Based on Multiwalled Carbon Nanotubes and Iron Tetrasulfonated Phthalocyanine Composite Modified Electrode

Hydrazines are well‐known for their diverse biological properties but especially for their toxicity. An amperometric hydrazine sensor was developed at multi‐walled carbon nanotubes (MWCNT) and iron tetrasulfonated phthalocyanine (FeTsPc) composite modified electrode for the first time. The TEM and UV‐Vis spectroscopy results revealed the successful formation of MWCNT/FeTsPc composite. Compared with the response of MWCNT and FeTsPc modified electrodes, the MWCNT/FeTsPc composite showed enhanced oxidation current response with lower overpotential for hydrazine. Under optimum conditions, the amperometric i–t response of hydrazine was linear in the concentration range from 100 nM L^?1 to 3 μM L^?1 with the detection limit of 7.6 nM L^?1. The response time of hydrazine was found as 6 s with a high sensitivity of 7.615 μA/μM L^?1 cm^?2.     

Ultra‐sensitive Amperometric Hydrazine Sensing via Dimethyl Glyoxomat Derived NiO Nanostructures

Here we report the synthesis of NiO nanostructures via glyoxomat assisted precipitation protocol using hydrothermal route under the influence of ammonia followed by annealing at 450 ^oC. These nanostructures were characterized via Scanning Electron Microscopy (SEM) and X‐ray Diffraction (XRD) method. The morphological investigation of the finally prepared NiO revealed foam‐like porous nanostructures. These NiO nanostructures were immobilized onto glassy carbon electrode (GCE) with nafion as binding material and used as highly sensitive and selective sensor for determining hydrazine in the range of 100–500 nM and 600–1600 nM with a calculated limit of detection (LOD) equal to 5 nM. The as prepared sensor was tested for the presence of various interfering species such as Na⁺, Cu²⁺, uric acid, hydrogen peroxide and glucose in the presence of equimolar concentration of hydrazine and negligible interference was noticed. The sensor was further tested for hydrazine detection using square wave voltammetry (SWV) however it only worked in the range of 50–1200 μM. Finally the sensor was successfully implemented for hydrazine determination in real water samples using amperometric protocol.     

Synthesis and Properties of a pH‐Insensitive Fluorescent Nitric Oxide Cheletropic Trap (FNOCT)

The synthesis and properties of the new fluorescent nitric oxide cheletropic trap (FNOCT) 14 , designed for the trapping and quantification of nitric oxide (NO) production in chemical and biological systems, is described (Scheme 3). The dicarboxylic acid 14 and the corresponding bis[(acetyloxy)methyl] ester derivative 15 of the FNOCT contain a 2‐methoxy‐substituted phenanthrene group as fluorophoric unit. The fluorescence of the reduced NO adduct of this FNOCT (λ_exc 320 nm, λ_em 380 nm) is pH‐independent. Trapping experiments were carried out in aqueous buffer solution at pH 7.4 with nitric oxide being added as a bolus as well as being released from the NO donor compound MAHMA NONOate (= (1Z)‐1‐{methyl[6‐(methylammonio)hexyl]amino}diazen‐1‐ium‐1,2‐diolate), indicating a trapping efficiency of ca. 50%. In a biological application, nitric oxide was scavenged from a culture of lipopolysaccharide‐stimulated rat alveolar macrophages. Under the applied conditions, a production of 11.1 ± 1.5 nmol of NO per hour and per 10⁵ cells was estimated.     

A New Nitric Oxide Gas Sensor Based on Reticulated Vitreous Carbon/Nafion and Its Applications

Reticulated vitreous carbon (RVC), and Nafion membrane are used to fabricate a composition electrode to measure nitric oxide (NO) concentration amperometrically in the gas phase. Limit of detection was found to be 6 ppb at an applied voltage of 0.66 V (vs. mercury sulfate reference electrode) with average response time of less than 30 seconds. The response of the sensor was linearly dependent on the concentration over the whole tested range from 19 ppb‐50 ppm of NO. Simplicity in electrode fabrication and consistent performance between individual sensors make RVC and Nafion attractive materials for detecting very low levels of nitric oxide gas in routine analysis.     

Binary Metal Oxide Adsorbed Graphene Modified Glassy Carbon Electrode for Detection of Riboflavin

Tungsten oxide (W) decorated titanium oxide (T) adsorbed onto a graphene (Gr) and modified the glassy carbon electrode for the electrochemical quantification of riboflavin (RF) in edible food and pharmaceuticals. For comparison, nanocomposites are formed using graphene oxide (GO), reduced graphene oxide (rGO) and pure graphite (G) sheets to study the electrochemical activities towards riboflavin. The ternary WTGr modified GCE shows the highest electrocatalytic activity due to synergetic interactions between the metal oxide and graphene. The electrochemical observations are supported by the SEM, HRTEM, XRD, UV-Vis, Zeta potential (ζ) and size data. The sensor shows a wide linear range 20 nM–2.5 μM with a detection limit 25.24 nM and sensitivity (4.249×10⁻⁸ A/nM). The fabricated sensor is validated in real samples.