Sensing hydrogen peroxide using a glassy carbon electrode modified with in-situ electrodeposited platinum-gold bimetallic nanoclusters on a graphene surface

Microchimica Acta - Platinum-gold nanoclusters (PtAu NCs) were electrodeposited on graphene placed on the surface of a glassy carbon electrode (GCE). The PtAu-graphene nanocomposite was...     

Reactions of VX, GB, GD, and HD with nanosize Al(2)O(3). Formation of aluminophosphonates.

Room-temperature reactions of VX, GB, GD, and HD with nanosize Al(2)O(3) (AP-Al(2)O(3)) have been characterized by (31)P, (13)C, and (27)Al MAS NMR. Nerve agents VX, GB, and GD hydrolyze to yield surface-bound complexes of their corresponding nontoxic phosphonates. At sufficiently high loadings, discreet aluminophosphonate complexes, Al[OP(O)(CH(3))OR](3), are generated which are identical to synthesized model compounds. Thus the reaction with phosphonic acids is not just surface-limited, but can continue to the core of alumina particles. HD mainly hydrolyzes at lower loadings to yield thiodiglycol (TG, 71%) and a minor amount of the CH-TG sulfonium ion (12%), although some elimination of HCl is also observed (17%). The reactive capacity for HD is evidently exceeded at high loadings, where complete conversion to TG is hindered. However, addition of excess water results in the quantitative hydrolysis of sorbed HD to CH-TG. On AP-Al(2)O(3) dried to remove physisorbed water, (13)C CP-MAS NMR detects a surface alkoxide consistent with that of TG.     

Nanomolar amperometric sensing of hydrogen peroxide using a graphite pencil electrode modified with palladium nanoparticles

We report on a simple and rapid method for the preparation of a disposable palladium nanoparticle-modified graphite pencil electrode (PdNP-GPE) for sensing hydrogen peroxide (H₂O₂). The bare and PdNP-modified GPEs were characterized by cyclic voltammetry and SEM. The two electrodes displayed distinct electrocatalytic activities in response to the electrochemical reduction of H₂O₂. The amperometric detection limits were 45 nM and 0.58 mM, respectively, for the PdNP-GPE and bare-GPE, at an S/N of 3. The electrodes can be prepared simply and at low cost, and represent a promising tool for sensing H₂O₂.

Non-enzymatic hydrogen peroxide sensor using an electrode modified with iron pentacyanonitrosylferrate nanoparticles

An electrochemical sensor was developed for determination of hydrogen peroxide (HP) based on a carbon ceramic electrode modified with iron pentacyanonitrosylferrate (FePCNF). The surface of an iron-doped CCE was derivatized in a solution of PCNF by cycling the electrode potential between ?0.2 and +1.3 V for about 60 times. The morphology and the composition of the resulting electrode were characterized by scanning electron microscopy and Fourier transform infrared techniques. The electrode displayed excellent response to the electro-oxidation of HP which is linearly related to its concentration in the range from 0.5 μM to 1300 μM. The detection limit is 0.4 μM, and the sensitivity is 849 A M ^?1?cm ^?2. The modified electrode was used to determination of HP in hair coloring creams as real samples.     

Photoelectrochemical determination of hydrogen peroxide using a gold electrode modified with fluorescent gold nanoclusters and graphene oxide

Nanocomposites consisting of gold nanoclusters and graphene oxide (AuNC/GO) were prepared and investigated with respect to the design of new sensors for hydrogen peroxide (H₂O₂). The AuNC/GO hybrid nanomaterials were deposited on a gold electrode by the layer-by-layer assembly method, where they showed enhanced photoelectrical and sensing properties. The presence of graphene oxide improves the photoinduced electron separation efficiency of the AuNCs, as well as the catalytic effect of AuNCs on the electroreduction of H₂O₂. Compared to an electrode modified with AuNCs only, the new electrodes display a more than ten-fold enhanced photocurrent at a working voltage of -500 mV (vs. Ag/AgCl), higher sensitivity for H₂O₂ (25.76 nA?mM^?1), lower LOD (2 μM) and extended linear range (from 30 μM to 5 mM). The sensors were applied to the determination of H₂O₂ extracted from living human umbilical vein endothelial cells stimulated by angiotensin II.

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Graphical abstract Graphene oxide (GO) not only improves the photoinduced charge separation efficiency of fluorescent gold nanoclusters (AuNCs) based photoelectrochemical sensors, but also enhances the catalytic property of AuNCs on the detection of hydrogen peroxide (H₂O₂).

     

Electrocatalytic sensing of hydrogen peroxide using a screen printed carbon electrode modified with nitrogen-doped graphene nanoribbons

We have synthesized nitrogen-doped graphene nanoribbons (N-GrNRs) by unzipping multi-walled carbon nanotubes (CNTs) under strongly oxidizing conditions and subsequent doping with nitrogen by a low-temperature hydrothermal method. The N-GNRs were characterized by transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy and Raman spectroscopy, and assembled on a disposable screen-printed carbon electrode to give a sensor for H₂O₂ that was characterized by cyclic voltammetry, electrochemical impedance spectroscopy, chronocoulometry and chronoamperometry. The nano-modified electrode displays enhanced electron transfer ability, and has a large active surface and a large number of catalytically active sites that originate from the presence of nitrogen atoms. This results in a catalytic activity towards H₂O₂ reduction at near-neutral pH values that is distinctly improved compared to electrodes modified with CNTs or unzipped (non-doped) CNTs only. At a working potential of −0.4 V (vs. Ag/AgCl), the amperometric responses to H₂O₂ cover the 5 to 2785 μM concentration range, with a limit of detection as low as 1.72 μM. This enzyme-free electrochemical sensor exhibits outstanding selectivity and long-term stability for H₂O₂ detection.

Nitrogen-doped graphene nanoribbons (N-GrNRs) were expediently synthesized for highly sensitive and selective detection of H₂O₂.

     

Sensor for traces of hydrogen peroxide using an electrode modified by multiwalled carbon nanotubes, a gold-chitosan colloid, and Prussian blue

An electrochemical sensor for trace levels of hydrogen peroxide (HP) was fabricated by the self-assembly of multi-walled carbon nanotubes, a gold-chitosan colloid, followed by electrodeposition of Prussian blue. The electrode was characterized by cyclic voltammetry, electrochemical impedance spectroscopy and other methods. The electrode shows well-defined peaks at 101 mV and 193 mV, the reduction current is linearly related to the concentration of HP in the range from 4.0 to and 19.6 μM. The detection limit of 3.36 μM (at an S/N of 3).     

Non-enzymatic amperometric hydrogen peroxide sensor using a glassy carbon electrode modified with gold nanoparticles deposited on CVD-grown graphene

A glassy carbon electrode (GCE) was modified with gold nanoparticles (AuNPs) coated on monolayer graphene (AuNP/MG) by direct in situ sputtering of AuNPs on CVD-generated graphene. This process avoids complicated polymer transfer and polymer cleaning processes and affords AuNPs with a clean surface. The monolayer graphene is ductile and well dispersed. The clean surface of the AuNPs renders this sensor superior to GCEs modified with AuNPs on reduced graphene oxide in terms of the amperometric non-enzymatic determination of hydrogen peroxide. The detection limit is 10 nM (S/N = 3) at 0.55 V (vs. SCE), which is lower than that for similar methods, and the response time is as short as 2 s. Another attractive feature of the sensor is its feasibility for large-scale production via CVD and sputtering.

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Graphical abstract Gold nanoparticles deposited onto monolayered graphene generated by chemical vapor deposition (CVD) are used for electrochemical sensing of H₂O₂, with the detection limit of 10 nM (S/N = 3) and response time of less than 2 s.

     

Enzyme-free electrocatalytic sensing of hydrogen peroxide using a glassy carbon electrode modified with cobalt nanoparticle-decorated tungsten carbide

Microchimica Acta - The authors describe a field effect transistor (FET) based immunoassay for the detection of inactivated ebola virus (EBOV). An equine antibody against the EBOV glycoprotein was...     

GC-MS分析水中GB、GD、VX 及其降解产物

甲氟膦酸异丙酯(GB)、甲氟膦酸特己酯(GD)、S-(2-二异丙基氨乙基)甲基硫赶膦酸乙酯(VX)等有机膦酸酯类化合物是毒性大、作用快的致死性化学战剂,而且会严重污染环境(水、泥土、粮食等),对人类和牲畜的生存构成巨大威胁.由于该类化合物在一定条件下易降解,因此对原型化合物及其降解产物的分析鉴定是确定是否被该类化合物污染的最重要指证.本文建立了水中GB等3个原型化合物和其相对应的降解产物甲基异丙氧基膦酸(IMPA)、甲基特乙氧基膦酸(PMPA)、甲基乙氧基膦酸(EMPA)以及它们的二级降解产物甲基磷酸(MPA)的分析鉴定方法.     

Non-enzymatic hydrogen peroxide sensor based on a nanoporous gold electrode modified with platinum nanoparticles

A novel non-enzymatic electrochemical sensor based on a nanoporous gold electrode modified with platinum nanoparticles was constructed for the determination of hydrogen peroxide (H₂O₂). Platinum nanoparticles exhibit good electrocatalytic activity towards hydrogen peroxide. The nanoporous gold (NPG) increases the effective surface area and has the capacity to promote electron-transfer reactions. With electrodeposition of Pt nanoparticles (NPs) on the surface of the nanoporous gold, the modified Au electrode afforded a fast, sensitive and selective electrochemical method for the determination of H₂O₂. The linear range for the detection of H₂O₂ was from 1.0 × 10^?7 M to 2.0 × 10^?5 M while the calculated limit of detection was 7.2 × 10^?8 M on the basis of the 3σ/slope (σ represents the standard deviation of the blank samples). These findings could lead to the widespread use of electrochemical sensors to detect H₂O₂.     

Amperometric hydrogen peroxide biosensor based on a glassy carbon electrode modified with polythionine and gold nanoparticles

We report on a novel hydrogen peroxide biosensor that was fabricated by the layer-by-layer deposition method. Thionine was first deposited on a glassy carbon electrode by two-step electropolymerization to form a positively charged surface. The negatively charged gold nanoparticles and positively charged horseradish peroxidase were then immobilized onto the electrode via electrostatic adsorption. The sequential deposition process was characterized using electrochemical impedance spectroscopy by monitoring the impedance change of the electrode surface during the construction process. The electrochemical behaviour of the modified electrode and its response to hydrogen peroxide were studied by cyclic voltammetry. The effects of the experimental variables on the amperometric determination of H₂O₂ such as solution pH and applied potential were investigated for optimum analytical performance. Under the optimized conditions, the biosensor exhibited linear response to H₂O₂ in the concentration ranges from 0.20 to 1.6?mM and 1.6 to 4.0?mM, with a detection limit of 0.067?mM (at an S/N of 3). In addition, the stability and reproducibility of this biosensor was also evaluated and gave satisfactory results.

Determination of hydrogen peroxide using glassy carbon and graphite/polyester composite electrodes modified by vanadium-doped zirconias

Synthetic monoclinic and tetragonal vanadium-doped zirconias (VZrO₂) with vanadium loading ranging from 0.5 to 15 mol% are used to modify glassy carbon and graphite/polyester composite electrodes able to detect oxygen and hydrogen peroxide in neutral aqueous media. Electrodes modified by monoclinic VZrO₂ decrease the overpotential for the reduction of oxygen and hydrogen peroxide in neutral and alkaline media and enhance their reduction currents with respect to unmodified carbon electrodes. This is associated to seven-coordinated vanadium centers isomorphously substituting zirconium ones in the ZrO₂ lattice. The catalytic effect shows site-selectivity, since it is almost entirely absent in tetragonal VZrO₂ in which eight-coordinated vanadium sites exists. Under optimized conditions using differential pulse detection mode, the height of the cathodic catalytic current peak is directly proportional to the hydrogen peroxide concentration over the concentration range 5-400 μM with a sensitivity of 170 μA/mM at pH 10.0. The detection limit (3σ) is calculated as 0.9 μM.     

Amperometric sensing of hydrogen peroxide using a glassy cabon electode modified with silver nanoparticles on poly(alizarin yellow R)

A sensitive amperometric sensor for hydrogen peroxide (HP) was constructed that is based on a glassy carbon electrode (GCE) modified with silver nanoparticles on poly(alizarin yellow R). The polymer was electropolymerized onto the surface of the GCE by cyclic voltammetry (CV), and the AgNPs were then electrodeposited onto its surface. The electrode was characterized by scanning electron microscopy and CV, and used for amperometric determination of HP. The electrode exhibits a favorable catalytic activity towards the reduction of HP, with a linear response range from 1.0???M to 450???M and a detection limit of 0.32???M. The sensor also displays high selectivity, excellent reproducibility, and good long-term stability.

Nonenzymatic sensing of hydrogen peroxide using a glassy carbon electrode modified with graphene oxide,a polyamidoamine dendrimer,and with polyaniline deposited by the Fenton reaction

A highly sensitive electrochemical sensor is described for the determination of H₂O₂. It is based on based on the use of polyaniline that was generated in-situ and within 1 min on a glassy carbon electrode (GCE) with the aid of the Fe(II)/H₂O₂ system. Initially, a 2-dimensional composite was prepared from graphene oxide and polyamidoamine dendrimer through covalent interaction. It was employed as a carrier for Fe(II) ions. Then, the nanocomposite was drop-coated onto the surface of the GCE. When exposed to H₂O₂, the Fe(II) on the GCE is converted to Fe(III), and free hydroxy radicals are formed. The Fe(III) ions and the hydroxy radicals catalyze the oxidation of aniline to produce electroactive polyaniline on the GCE. The resulting sensor, best operated at a working potential as low as 50 mV (vs. SCE) which excludes interference by dissolved oxygen, has a linear response in the 500 nM to 2 mM H₂O₂ concentration range, and the detection limit is 180 nM. The sensor was successfully applied to the determination of H₂O₂ in spiked milk and fetal bovine serum samples.

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Graphical abstract Schematic presentation of a sensitive electrochemical sensor employed for detection of H₂O₂ in sophisticated matrices by using graphene oxide-PAMAM dendrimer as initiator container and Fe²⁺/H₂O₂ system as signal enhancer.

     

A fluorescent hydrogen peroxide probe based on a ‘click’ modified coumarin fluorophore

Herein a water-soluble ‘click’ modified coumarin-based fluorescent probe for hydrogen peroxide is reported. This probe shows significant intensity increases (up to fivefold) in near-green fluorescence upon reaction with hydrogen peroxide, and good selectivity over other reactive oxygen species.