MEDIATORLESS HYDROGEN-PEROXIDE ELECTRODE BASED ON HORSERADISH-PEROXIDASE ENTRAPPED IN POLY(O-PHENYLENEDIAMINE)

A mediatorless H2O2 sensor based on coelectropolymerization of horse radish peroxidase (HRP) and o-phenylenediamine (o-PD) is described. The electrode responds to H2O2 in a few seconds and gives a current density of 73.3 nA 1 mu mol(-1) cm(-2) at -100 mV

Electrochemical measurement of hydrogen peroxide in plasma: Evaluation of freshwater prawn (Macrobrachium rosenbergii) and crucian carp (Cyprinus carpio) phagocytes under natural conditions

An electrochemical technique for the real-time detection of hydrogen peroxide (H2O2) was employed to describe respiratory burst activity (RBA) of phagocytes in plasma which can be used to evaluate the ability of immune system and disease resistance. The method is based upon the electric current changes, by redox reaction on platinum electrode of extracellular hydrogen peroxide (H2O2) released from phagocytes stimulated by the zymosan at 680 mV direct current (d.c.). Compared with the control, activation of respiratory burst by zymosan particles results in a high amperometric response, and a current peak was obtained during the whole monitoring process. The peak current was proved by addition Of Cu2+ and other controls, to be the result of intense release of H2O2 from phagocytes. The peak area was calculated and used to evaluate the quantity of effective H2O2, which represents the quantity of H2O2 beyond the clearance of related enzymes in plasma. According to Faraday's law, the phagocytes' ability of prawns to generate effective H2O2 was evaluated from 1.253 x 10(-14) mol/cell to 6.146 x 10(-14) mol/cell, and carp from 1.689 x 10(-15) Mol/Cell to 7.873 x 10(-1)5 mol/cell. This method is an acute and quick detection of extracellular effective H2O2 in plasma and reflects the capacity of phagocytes under natural conditions, which could be applied for selecting species and parents with high immunity for breeding in aquaculture. (c) 2007 Elsevier Ltd. All rights reserved.

Hydrogen peroxide biosensor based on horseradish peroxidase-Au nanoparticles at viologen grafted glassy carbon electrode

A novel hydrogen peroxide biosensor was fabricated that is based on horseradish peroxidase-Au nanoparticles immobilized on a viologen-modified glassy carbon electrode (GCE) by amino cation radical oxidation in basic solution. The immobilized BAPV acts as a mediator and a covalent linker between GCE and the Au nanoparticles. The biosensor exhibited fast response, good reproducibility, and long-term stability.

Determination of concentrated hydrogen peroxide at single-walled carbon nanohorn paste electrode

Single-walled carbon nanohorn (SWCNH) paste electrode was used for amperometric determination of concentrated hydrogen peroxide, and was compared with other carbon electrodes. The calibration plots are linear from 0.5 to 100 mM at activated SWCNH paste electrode and edge plane graphite (EPG) electrode. In contrast, the calibration plots are linear only at concentrations lower than 45 mM at graphite paste electrode, multi-walled carbon nanotube paste electrode, and glassy carbon electrode.

Hydrogen peroxide biosensor based on direct electrochemistry of soybean Peroxidase immobilized on single-walled carbon nanohorn modified electrode

Single-walled carbon nanohorns (SWCNHs) were used as a novel and biocompatible matrix for fabricating biosensing devices. The direct immobilization of acid-stable and thermostable soybean peroxidase (SBP) on SWCNH modified electrode surface can realize the direct electrochemistry of enzyme. Cyclic voltammogram of the adsorbed SBP displays a pair of redox peaks with a formal potential of -0.24V in pH 5 phosphate buffer solution.

A novel hydrogen peroxide sensor based on horseradish peroxidase immobilized on colloidal Au modified ITO electrode

A novel method to fabricate a hydrogen peroxide sensor was developed by immobilizing horseradish peroxidase (HRP) on colloidal An modified ITO conductive glass support. The cleaned glass support was modified with (3-aminopropyl)trimethoxysilane (APTMS) first to yield an interface for the assembly of colloidal An. Then 15 nm colloidal Au particles were chemisorbed onto the amine groups of the APTMS. Finally, HRP was adsorbed onto the surface of the colloidal An. The immobilized HRP displayed excellent electrocatalytical response to the reduction of hydrogen peroxide. The performance and factors influencing the resulted biosensor were studied in detail. The resulted biosensor exhibited fast amperometric response (within 5 s) to H2O2. The detection limit of the biosensor was 8.0 mumol l(-1), and linear range was from 20.0 mumol l(-1) to 8.0 mmol l(-1). Furthermore, the resulted biosensor exhibited high sensitivity, good reproducibility, and long-term stability.

A novel hydrogen peroxide sensor based on horseradish peroxidase immobilized in DNA films on a gold electrode

A novel third-generation hydrogen peroxide (H2O2) biosensor was developed by immobilizing horseradish peroxidase (HRP) on a biocompatible gold electrode modified with a well-ordered, self-assembled DNA film. Cysteamine was first self-assembled on a gold electrode to provide an interface for the assembly of DNA molecules. Then DNA was chemisorbed onto the self-assembled monolayers (SAMs) of cysteamine to form a network by controlling DNA concentration. The DNA-network film obtained provided a biocompatible microenvironment for enzyme molecules, greatly amplified the coverage of HRP molecules on the electrode surface, and most importantly could act as a charge carrier which facilitated the electron transfer between HRP and the electrode. Finally, HRP was adsorbed on the DNA-network film. The process of the biosensor construction was followed by atomic force microscopy (AFM). Voltammetric and time-based amperometric techniques were employed to characterize the properties of the biosensor derived. The enzyme electrode achieved 95% of the steady-state current within 2 s and had a 0.5 mu mol l(-1) detection limit of H2O2. Furthermore, the biosensor showed high sensitivity, good reproducibility, and excellent long-term stability.

Sol-gel-derived alpha(2)-K7P2W17VO62/graphite/organoceramic composite as the electrode material for a renewable amperometric hydrogen peroxide sensor

The conductive alpha (2)-K7P2W17VO62/graphite/organoceramic composite was prepared by dispersing alpha (2)-K7P2W17VO62 and graphite powder in a propyltrimethoxysilane-based sol-gel solution; it was used as the electrode material for an amperometric hydrogen peroxide sensor. The modified electrode had a homogeneous mirror-like surface and showed well defined cyclic voltammograms. Square-wave voltammetry was employed to study the pH-dependent electrochemical behavior of c alpha (2)-K7P2W17VO62 doped in the graphite organoceramic matrix, and the experiment showed that both protons and sodium cations participated in the odor process. A hydrodynamic voltammetric experiment was performed to characterize the electrode as an amperometric sensor for the determination of hydrogen peroxide. The sensor can be renewed easily in a repeatable manner by a mechanical polishing step and has a long operational lifetime. (C) 2000 Elsevier Science B.V. All rights reserved.

Amperometric enzyme electrode for the determination of hydrogen peroxide based on sol-gel/hydrogel composite film

A new type of organic-inorganic composite material was prepared by sol-gel method, and a peroxidase biosensor was fabricated by simply dropping sor-gel-peroxidase mixture onto glassy carbon electrode surface. The sol-gel composite film and enzyme membrane were characterized by Fourier-transform infrared (FT-IR) spectroscopy and EQCM, the electrochemical behavior of the biosensor was studied with potassium hexacyanoferrate(II) as a mediator, and the effects of pH and operating potential were explored for optimum analytical performance by using amperometric method. The response time of the biosensor was about 10 s; the linear range was up to 3.4 mM with a detection limit of 5 x 10(-7) M. The sensor also exhibited high sensitivity (15 mu A mM(-1)) and good long-term stability. In addition, the performance of the biosensor was investigated using flow injection analysis (FIA), and the determination of hydrogen peroxide in real samples was discussed. (C)2000 Elsevier Science B.V. All rights reserved.

Hydrogen peroxide biosensor with enzyme entrapped within electrodeposited polypyrrole based on mediated sol-gel derived composite carbon electrode

A novel amperometric biosensor for the detection of hydrogen peroxide was described. The biosensor was constructed by electrodepositing HRP/PPy membrane on the surface of ferrocenecarboxylic acid mediated sol-gel derived composite carbon electrode. The biosensor gave response to hydrogen peroxide in a few seconds with detection limit of 5.0 x 10(-5) M (based on signal:noise = 3). Linear range was upto 0.2 mM. The biosensor exhibited a good stability. (C) 2001 Elsevier Science B.V. All rights reserved.

A hydrogen peroxide biosensor combined HRP doped polypyrrole with ferrocene modified sol-gel derived composite carbon electrode

A novel amperometric biosensor for the detection of hydrogen peroxide is described. The biosensor was constructed by electrodepositing HRP/PPy membrane on the surface of ferrocenecarboxylic acid mediated sol-gel derived composite carbon electrode. The biosensor gives response to hydrogen peroxide in a few seconds with detection limit of 5x10(-7) mol (.) L-1 (based on signal : noise=3). Linear range is up to 0.2 mmol (.) L-1.

Chemiluminescent determination of luminol and hydrogen peroxide using hematin immobilized in the bulk of a carbon paste electrode

A new method for immobilization of a chemiluminescent reagent is presented. It is based on immobilizing hematin, a catalyst for luminol reaction, in the bulk of a carbon paste electrode. Bulk-immobilization allows renewal of the surface by simple polishing or cutting to expose anew and fully active surface in the case of fouling or deactivation by other means. By using a hematin-modified carbon paste electrode, the applied potential shifted negatively compared with that of unmodified carbon paste electrode or a glassy carbon electrode. The shift in potential changed the reaction processes and effectively stabilized the chemiluminescent signal during successive measurements. Under this condition, the signal was stable during 3 hours of continuous operation. The log-log plots of the emitted light intensity vs. luminol concentration and hydrogen peroxide concentration were linear over the region 10(-8)-10(-3) mol L-1 with a correlation coefficient of 0.999 and 3.9 x 10(-6)-10(-3) mol L-1 with a correlation coefficient of 0.994, respectively. Application of this method for other chemiluminescent and bioluminescent systems is suggested.