Catalytic Reduction Of Hydrogen Peroxide Research Articles

Plasmonic Imaging of Electrochemical Reactions at Individual Prussian Blue Nanoparticles.

Prussian blue is an iron-cyanide-based pigment steadily becoming a widely used electrochemical sensor in detecting hydrogen peroxide at low concentration levels. Prussian blue nanoparticles (PBNPs) have been extensively studied using traditional ensemble methods, which only provide averaged information. Investigating PBNPs at a single entity level is paramount for correlating the electrochemical activities to particle structures and will shed light on the major factors governing the catalyst activity of these nanoparticles. Here we report on using plasmonic electrochemical microscopy (PEM) to study the electrochemistry of PBNPs at the individual nanoparticle level. First, two types of PBNPs were synthesized; type I synthesized with double precursors method and type II synthesized with polyvinylpyrrolidone (PVP) assisted single precursor method. Second, both PBNPs types were compared on their electrochemical reduction to form Prussian white, and the effect from the different particle structures was investigated. Type I PBNPs provided better PEM sensitivity and were used to study the catalytic reduction of hydrogen peroxide. Progressively decreasing plasmonic signals with respect to increasing hydrogen peroxide concentration were observed, demonstrating the capability of sensing hydrogen peroxide at a single nanoparticle level utilizing this optical imaging technique.

A sandwich-type electrochemical immunosensor based on Au@Pd nanodendrite functionalized MoO2 nanosheet for highly sensitive detection of HBsAg

In this work, a sandwich-type electrochemical immunosensor was fabricated to the effective detection of hepatitis B surface antigen (HBsAg). The designed electrochemical immunosensor was based on Au core and Pd shell nanodendrites loaded on amino functionalized molybdenum dioxide nanosheets (Au@Pd NDS/NH2–MoO2 NSs) as the secondary antibody (Ab2) label and silver nanoparticles were loaded by electrodeposited (D-Ag NPs) on the surface of electrode as the platform. Because of the synergistic effect and abundant catalytic activity sites provided by surface dendrite structure, Au@Pd NDs were more effective than single gold and palladium nanoparticles in catalytic reduction of hydrogen peroxide (H2O2). MoO2 had the good catalytic capacity for reduction of H2O2 and favourable electrical conductivity. Hence, the obtained Au@Pd NDS/NH2–MoO2 NSs were more effective than Au@Pd NDs and NH2–MoO2 NSs in catalytic reduction of hydrogen peroxide attribute to a synergistic effect. Also, Ag NPs with admirable electrical conductivity and biocompatibility were used as sensing platforms and primary antibodies (Ab1) carriers, which can accelerate the electron transfer and improve the sensitivity of the immunosensor. Here, the proposed electrochemical immunosensor offered a wide linear interval from 10 fg mL−1 to 100 ng mL−1 and the lower limit of detection of 3.3 fg mL−1 (S/N = 3) for detection of HBsAg under optimal experimental conditions. Furthermore, the accuracy of the actual serum sample analysis was satisfactory, which showed that the electrochemical immunosensor possessed a good application prospect in clinical detection.

The mimetic assembly of cobalt prot-porphyrin with cyclodextrin dimer and its application for H2O2 detection

A biomimetic assembly of per-O-methylated-cyclodextrin dimer with cobalt proto-porphyrin (CoIII-PPIX@Py2CD) was achieved via covalent linkage between CoIII of CoIII-PPIX and pyridine N of Py2CD (primarily synthesized by the acyl chlorination reaction of two β-CDs monomers with 3,5-bis (bromomethyl) pyridine). Ultraviolet–visible (UV–vis) and circular dichroism (CD) absorption spectroscopy, and NMR hydrogen spectroscopy (H1-NMR) were adopted to carefully characterize the structure of Py2CD and its functional assembly with CoIII-PPIX. X-ray photoelectron spectroscopy (XPS) was employed to affirm the binding of the as-obtained CoIII-PPIX@Py2CD, whose electrochemical kinetics were extensively studied to validate the feasibility in the catalytic reduction of hydrogen peroxide (H2O2). The developed sensor displayed the wide linear range for H2O2 detection and the low detection limit of 2.47 × 10−7 M. This work sheds some constructive lights on rational design and synthesis of preeminently biomimic carrier and high cost-effectiveness catalyst for (bio)analytical applications.

Analytical applications of Cu@PtPd/C nanoparticles for the quantification of hydrogen peroxide

This work reports a non-enzymatic amperometric sensor for hydrogen peroxide based on the use of a glassy carbon composite electrode modified with core-shell Cu@PtPd/C nanoparticles. Cu@PtPd/C presents an important electrocatalytic activity towards hydrogen peroxide reduction. The comparison of the sensitivities and the charge transfer resistances for hydrogen peroxide at the glassy carbon composite electrode modified with 5.0% w/w Pt/C, Pd/C, Pd/C + Pt/C and Cu@PtPd/C demonstrate a clear synergism on the catalytic reduction of hydrogen peroxide at −0.100 V when having Pt, Pd and Cu incorporated in the core-shell nanostructure. The best compromise between sensitivity, reproducibility and response time was reached with 20.0% w/w Cu@PtPd/C. For the selected sensor (glassy carbon composite electrode containing 20.0% w/w GCPE/Cu@PtPd/C) the analytical parameters are highly competitive compared to similar devices reported in the last years, with a linear relationship between current and hydrogen peroxide concentration between 5.0 × 10−6 and 2.5 × 10−4 M, sensitivity of (5.30 ± 0.09) × 105 μAM−1 cm−2 (r2 = 0.998) and detection limit of (3.7 ± 0.5) × 10−7 M. The resulting sensing platform was successfully used for the quantification of hydrogen peroxide in a mouth-wash sample.

Facile Synthesis of Cuprous Oxide/Gold Nanocomposites for Nonenzymatic Amperometric Sensing of Hydrogen Peroxide

AbstractIn this work, a facile preparation method of cuprous oxide/gold (Cu2O/Au) nanocomposite was successfully developed. The process consisted of one‐pot co‐reduction of HAuCl4 and CuSO4 using ascorbic acid (AA) as a reducing agent at room temperature under magnetic stirring. The structures and compositions of the as‐prepared products were characterized by SEM, EDS, and XRD. Cyclic voltammetry and chronopotentiometry studies revealed that the as‐prepared cubic Cu2O/Au nanocomposites showed enhanced performance towards the non‐enzymatic catalytic reduction of hydrogen peroxide (H2O2) when compared to single‐component Cu2O nanocubes. The linear range of H2O2 determination spanned over 4 orders of magnitude (1 μM∼16.7 mM) and the detection limit was low as 0.45 μM (S/N=3). The enhanced performance of cubic Cu2O/Au was attributed to: i) the synergistic effect between Cu2O and Au, ii) the increase in surface area induced by the reduced size of the nanocubes, and iii) the improved electrical conductivity due to the presence of Au in the particles. Overall, the cubic Cu2O/Au nanocomposites prepared by the proposed method hold great promise for future practical use in H2O2 detection.

A novel Prussian blue‐magnetite composite synthesized by self‐template method and its application in reduction of hydrogen peroxide

A novel Prussian blue (PB)‐Fe3O4 composite has been prepared for the first time by self‐template method using PB as the precursor. According to this method, Fe3O4 nanoparticles distributed uniformly on the surface of PB cube. The feed ratio of sodium acetate to PB has been proved to be a key factor for magnetic properties and electro‐catalysis properties of the composite. Under the experimental conditions, the saturation magnetization value (Ms) of PB‐Fe3O4–2 composite was 22 emug−1, while the Ms value of other samples reduced. The composites also showed a good peroxidase‐like activity for the oxidation of substrate 3,3,5,5‐tetramethylbenzidine (TMB) in the presence of H2O2. The catalytic reduction of hydrogen peroxide capacity was PB‐Fe3O4–1> PB‐Fe3O4–2> PB‐Fe3O4–3> PB‐Fe3O4–0, which confirmed the Fe(II) centres in PB surface and Fe3O4 nanoparticles had synergistic effect on catalytic reduction of hydrogen peroxide.

Pt modified carbon fiber microelectrode for electrochemically catalytic reduction of hydrogen peroxide and its application in living cell H2O2 detection

In this contribution, a new carbon fiber microelectrode (CFME) for detection of hydrogen peroxide (H2O2) is constructed with a rapid and low-cost method based on the electrochemical etching technique and the electro-deposition of platinum (Pt) nanoparticles, and the potential application in electrochemical bioanalysis has been explored. It is observed that when the CFME modified in 5mmol/L chloroplatinic acid with 0.5mol/L H2SO4 used as supporting electrolyte, the as-prepared Pt modified carbon fiber microelectrode (Pt/CFME) demonstrates an excellent electrochemically catalytic activity, which exhibited a wide linear in relevant detection for the reduction of H2O2, ranging from 0.044 to 12.30mmol/L with the limit of 44μmol/L. Moreover, our results illustrate that the Pt/CFME electrode can be readily utilized in scanning electrochemical microscope (SECM) studies to detect H2O2 release from human glioblastoma cells U87 when stimulated with ascorbic acid (AA).

Fe3O4 on Graphene Oxide Nanosheets for Electrochemiocal Detection of Cancer Biomarker Proteins

An ultrasensitive mediator-free electrochemical detection method for proteins has been developed on an 8-sensors microfluidic platform. In this method, a sandwich immunoassay approach was used to detect prostate cancer biomarkers on screen-printed carbon electrodes. Fe3O4 nanoparticles with peroxidase like-activity were loaded onto graphene oxide nano-sheets resulting in a Fe3O4@GO composite with 1 µm average diameter as determined by dynamic light scattering and electron microscopy. Voltammetric studies and colorimetric assays confirmed the Fe3O4@GO composite material exhibited catalytic activity toward hydrogen peroxide reduction. Detection antibodies were covalently attached to Fe3O4@GO composite, the resulting biocomposite was used as a detection label in sandwich immunoassays for Prostate Specific Antigen (PSA) and Prostate Specific Membrane antigen (PSMA). The sensor surfaces of the array were coated with electrochemically reduced graphene oxide to improve conductivity and increase surface area, and then capture antibodies were attached through either adsorption or covalent binding to residual carboxylic groups on surface. An optimized simple microfluidic system was used to deliver reagents to the electrode arrays and wash/remove unbound species. This sandwich assay based on catalytic reduction of hydrogen peroxide by Fe3O4@GO detection labels exhibited detection limits of 61 fg/mL for PSA and 9.8 fg /mL for PSMA.

Comparison of ferrite nanoparticles obtained electrochemically for catalytical reduction of hydrogen peroxide

Ferrites of iron, cobalt, and nickel were used as a non-enzymatic sensor for detection of hydrogen peroxide. X-ray diffraction (XRD) and transmission electron microscopy revealed that the nanoparticles obtained by electrochemical route and varying the parameters synthesis show similar size of around 20 nm and a relation metal/iron equal to 1/2. The effect of pH, temperature, amount of nanoparticles, and potential has been studied to obtain the best sensor properties in terms of sensitivity and linear response. The mechanism has been attributed to the oxidation of Fe2+, Co2+, and Ni2+ in the octahedral position of the spinel that enhances the catalytic reduction of hydrogen peroxide. The best sensor has been obtained with magnetite (iron ferrite) with a detection limit of 7.3 × 10−6 M and a sensitivity of 4.0 × 10−4 μA/M. The magnetite was also applied to determine hydrogen peroxide in commercial contact lens cleaner Novoxy® with satisfactory results.

Electrochemical Determination of Hydrogen Peroxide and Glucose by Titanium(IV) Oxide Nanotube Arrays

Titanium(IV) oxide nanotube arrays (TiO2) prepared by electrochemical oxidation were used as a sensor for the catalytic reduction of hydrogen peroxide. The effects of pH, applied voltage, interferences, and linear dynamic range were characterized. The electrode showed rapid response and a linear dynamic range from 5.0 micromolar to 12.0 millimolar in phosphate buffer at pH 6.5 at a working voltage of −0.8 volt. The maximum sensitivity was 474 milliamperes per molar per square centimeter with good reproducibility and reusability. The electrode was also employed for the electrochemical determination of glucose without a mediator by the immobilization of glucose oxidase on the electroactive surface. The resulting biosensor exhibited good activity and rapid response toward glucose and allowed the determination of glucose from 20 micromolar to 1 millimolar and 1–10 millimolar.

A HYDROGEN PEROXIDE SENSOR BASED ON PRUSSIAN BLUE AND DNA-MODIFIED ELECTRODE

The polyvinylpyrrolidone (PVP) protected Prussian blue (PB) nanoparticles were prepared for use as a sensor for the catalytic reduction of hydrogen peroxide. The nanoparticles were used to modify a gold electrode, which was applied to detect hydrogen peroxide. Impedance spectra and differential pulse voltammetry were applied to detect the performance of the novel electrode and its response to H2O2 and Ramos cell smash fluid. Under the optimized experimental conditions, hydrogen peroxide was detected in a linear range of 6.25 × 10−7 to 1.0 × 10−5 mol · L−1, and the detection limit was 7.12 × 10−8 mol · L−1 according to 3σ rule. Under the same conditions, hydrogen peroxide was determined in Ramos cell smash fluid with a linear range from 400–80000 mol mL−1, with a detection limit of 114 mL−1 according to 3σ rule. The modified electrode with Prussian blue nanoparticles displayed high sensitivity, good reproducibility, and long-term stability to hydrogen peroxide.

Gold nanoparticles deposited on amine functionalized silica sphere and its modified electrode for hydrogen peroxide sensing

A facile and environmentally benign synthetic route to decorate preformed amine functionalized silica spheres (SiO2) by in situ formation of gold nanoparticles (Au NPs) at three different concentrations (1, 2, and 3 mM) of Au precursor (HAuCl4) is reported. UV-Visible absorption spectra of SiO2@Au (1, 2, and 3 mM) NPs showed a characteristic surface plasmon resonance band due to the presence of Au NPs and transmission electron microscopic images confirmed that the Au NPs were accommodated on the surface of the amine functionalized SiO2 spheres without aggregation. Herein, N-(3-(trime- thoxysilyl) propyl) diethylenetriamine acted as both reducing and stabilizing agent for the Au NPs and no other protecting agents were used. Cyclic voltammogram recor- ded for the SiO2@Au NPs modified glassy carbon (GC) electrode showed a characteristic electrochemical response due to the presence of Au NPs on the electrode. Electro- catalytic reduction of hydrogen peroxide (H2O2) was car- ried out at the SiO2@Au (1, 2, and 3 mM) NPs modified GC electrodes, among which the SiO2@Au (3 mM) NPs modified GC electrode produced the highest catalytic cur- rent. Electrochemical sensing of H2O2 was performed using linear sweep voltammetry at the SiO2@Au (3 mM) NPs modified GC electrode with an experimental detection limit of 5 lM.

THIOCYANATE: A potentially useful therapeutic agent with host defense and antioxidant properties

Thiocyanate (SCN) functions in host defense as part of the secreted lactoperoxidase (LPO) microbicidal pathway. SCN is the preferred substrate for LPO-driven catalytic reduction of hydrogen peroxide (H2O2) forming hypothiocyanous acid (HOSCN). HOSCN is selectively generated by many peroxidase enzymes that can utilize SCN including: eosinophil peroxidase (EPO), gastric peroxidase (GPO), myeloperoxidase (MPO), salivary peroxidase (SPO), and thyroid peroxidase (TPO). These enzymes generate HOSCN through a two-electron halogenation reaction. HOSCN is a potent microbicidal agent that kills or nullifies invading pathogens but is better tolerated by host tissue. Some controversy exists as to whether physiologic levels of HOSCN are non-toxic to host tissue, but the disagreement appears to be based on results of enzymatic generation (yielding moderate steady-state exposure) versus direct high level acute exposure in mammalian cell lines. This apparent duality is also true of other endogenous oxidants such as hydrogen peroxide and relates to the difference between physiologically relevant oxidant production versus supra-physiologic bolus dosing approaches. SCN has antioxidant properties that include the ability to protect cells against oxidizing agents such as hypochlorous acid (HOCl) and repair protein chloramines. SCN is an important endogenous molecule that has the potential to interact in complex and elegant ways with its host environment and foreign organisms. SCN's diverse properties as both host defense and antioxidant agent make it a potentially useful therapeutic.

Highly Sensitive Molecularly Imprinted Electrochemical Sensor Based on the Double Amplification by an Inorganic Prussian Blue Catalytic Polymer and the Enzymatic Effect of Glucose Oxidase

A novel strategy to improve the sensitivity of molecularly imprinted polymer (MIP) sensors was proposed. An electrocatalytic Prussian blue (PB) film was electrochemically polymerized on an electrode surface to fabricate an MIP electrochemical sensor using oxytetracycline (OTC) as a template. The OTC determination relied on a competition reaction between OTC and glucose-oxidase-labeled OTC and the catalytic reduction of hydrogen peroxide by the modified PB film. Experimental results show that double amplification, which is based on the catalysis of inorganic PB films and the enzymatic effect of glucose oxidase, can remarkably increase the assay sensitivity. The main experimental conditions (including electrocatalysis of the PB film, pH effects, incubation and competition times, and anti-interference) were optimized. This novel MIP sensor can offer an femtomole detection limit for OTC. In addition, the feasibility of its practical applications has been demonstrated in the analysis of a series of real milk samples.

Formation of a robust and stable film comprising ionic liquid and polyoxometalate on glassy carbon electrode modified with multiwalled carbon nanotubes: Toward sensitive and fast detection of hydrogen peroxide and iodate

A robust and stable film comprising n-octylpyridinum hexafluorophosphate ([C 8Py][PF 6]) and 1:12 phosphomolybdic acid (PMo 12) was prepared on glassy carbon electrodes modified with multiwall carbon nanotubes (GCE/MWCNTs) by dip-coating. The cyclic voltammograms of the GCE/MWCNTs/[C 8Py][PF 6]-PMo 12 showed three well-defined pairs of redox peaks due to the PMo 12 system. The surface coverage for the immobilized PMo 12 and the average values of the electron transfer rate constant for three pairs of redox peaks were evaluated. The GCE/MWCNTs/[C 8Py][PF 6]-PMo 12 showed great electrocatalytic activity towards the reduction of H 2O 2 and iodate. The kinetic parameters of the catalytic reduction of hydrogen peroxide and iodate at the electrode surface and analytical features of the sensor for amperometric determination of hydrogen peroxide and iodate were evaluated.

Sandwich-type amperometric immunosensor for human immunoglobulin G using antibody-adsorbed Au/SiO2 nanoparticles

A novel sandwich-type electrochemical immunosensor for human immunoglobulin G (hIgG) was developed using Au/SiO2 nanoparticles (NPs) with adsorbed horseradish peroxidase-anti-hIgG as the secondary antibody layer. The signal readout is based on the amperometric response to the catalytic reduction of hydrogen peroxide at an AuNPs-polythionine modified glassy carbon electrode. Under optimized conditions, the linear range is from 0.1 to 200 ng·mL−1, with a detection limit of 0.035 ng·mL−1 (at an S/N of 3). The immunosensor exhibited a performance that is better than that based on Au/SiO2NPs-excluded secondary antibody.

Oxygen and hydrogen peroxide reduction catalyses in neutral aqueous media using copper ion loaded glassy carbon electrode electrolyzed in ammonium carbamate solution

An aminated glassy carbon electrode (AGCE) can be obtained by the electrode oxidation of glassy carbon electrode in ammonium carbamate solution. In the cyclic voltammetric experiments, the electrode reduction of the dissolved oxygen began from −0.15 V vs. Ag/AgCl in neutral aqueous media when the aminated glassy carbon electrode was used as a working electrode although it began from −0.40 V vs. Ag/AgCl when a polished GCE was used. The nitrogen containing groups introduced by the electrode oxidation of carbamic acid must be related with the acceleration of the electron transfer rate of oxygen. Moreover, the new reduction wave of the dissolved oxygen appeared at +0.15 V vs. Ag/AgCl when copper (II) ion was coordinated to AGCE surface. This reduction potential of oxygen coincided with that of copper (II) ion and this fact suggests that the coordinated copper ion to the aminated carbon surface works as a redox mediator of oxygen. The reduction product of oxygen was monitored by rotating platinum ring – aminated glassy carbon disk electrode, and it was found that most of oxygen was reduced to water in a potential range negative than −0.4 V vs. Ag/AgCl. By using AGCE, it was recognized that the catalytic reduction of hydrogen peroxide was also taken place as well as oxygen reduction.

Thiol cofactors for selenoenzymes and their synthetic mimics

The importance of selenium as an essential trace element is now well recognized. In proteins, the redox-active selenium moiety is incorporated as selenocysteine (Sec), the 21st amino acid. In mammals, selenium exerts its redox activities through several selenocysteine-containing enzymes, which include glutathione peroxidase (GPx), iodothyronine deiodinase (ID), and thioredoxin reductase (TrxR). Although these enzymes have Sec in their active sites, they catalyze completely different reactions and their substrate specificity and cofactor or co-substrate systems are significantly different. The antioxidant enzyme GPx uses the tripeptide glutathione (GSH) for the catalytic reduction of hydrogen peroxide and organic peroxides, whereas the larger and more advanced mammalian TrxRs have cysteine moieties in different subunits and prefer to utilize these internal cysteines as thiol cofactors for their catalytic activity. On the other hand, the nature of in vivo cofactor for the deiodinating enzyme ID is not known, although the use of thiols as reducing agents has been well-documented. Recent studies suggest that molecular recognition and effective binding of the thiol cofactors at the active site of the selenoenzymes and their mimics play crucial roles in the catalytic activity. The aim of this perspective is to present an overview of the thiol cofactor systems used by different selenoenzymes and their mimics.

A novel nanobiocomposite based glucose biosensor using neutral red functionalized carbon nanotubes

The performance of a new glucose biosensor based on the combination of biocatalytic activity of glucose oxidase (GOx) with the electrocatalytic properties of CNTs and neutral red (NR) for the determination of glucose is described. This sensor is comprised of a multiwalled carbon nanotubes (MWNTs) conduit functionalized with NR and Nafion (Nf) as a binder and glucose oxidase as a biocatalyst. Neutral red was covalently immobilized on carboxylic acid groups of the CNTs via carbodiimide reaction. The functionalized MWNTs were characterized by microscopic, spectroscopic and thermal methods. The MWNT–NR–GOx–Nf nanobiocomposite was prepared by mixing the GOx solution with NR functionalized CNTs followed by mixing homogeneously with Nafion. The performance of the MWNT–NR–GOx–Nf nanobiocomposite modified electrode was examined by electrochemical impedance spectroscopy and cyclic voltammetry. The catalytic reduction of hydrogen peroxide liberated from the enzymatic reaction of glucose oxidase upon glucose with NR functionalized CNTs leads to the selective detection of glucose. The excellent electrocatalytic activity and the influence of nanobiocomposite film result in good characteristics such as low potential detection of glucose with a large determination range from 1 × 10 −8 to 1 × 10 −3 M with a detection limit of 3 × 10 −9 M glucose, a short response time (with 4 s), good stability and anti-interferent ability. The improved electrocatalytic activity and stability made the MWNT–NR–GOx–Nf nanobiocomposite biosensor system a potential platform to immobilize different enzymes for other bioelectrochemical applications.

Catalytic reduction of oxygen and hydrogen peroxide by nanoporous gold

Nanoporous gold (NPG) made by dealloying silver/gold alloys is a mesoporous metal combining high surface area and high conductivity. Recently, NPG has been shown to exhibit some of the high catalytic activity previously associated only with supported gold nanoparticles. Here we describe how NPG acts as a catalyst for the oxygen reduction reaction in both gas phase (in fuel cells) and aqueous environments (using rotating disk electrochemistry). NPG was found to reduce oxygen via an effectively 4-four electron route comprised of a first reduction of oxygen to hydrogen peroxide, and then an unusually active further catalytic reduction of hydrogen peroxide to water.