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Amperometric Biosensor (amperometric + biosensor)

Distribution by Scientific Domains

Chemistry	95%

Selected Abstracts

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

ELECTROANALYSIS, Issue 21 2006
Mustafa Musameh
Abstract 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 ,M of the tested RSNO species. The lowest detection limit is obtained for S -nitrosocysteine (CysNO), at approx. 0.2,,M. 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. [source]

A New Amperometric Biosensor Based on HRP/Nano-Au/L -Cysteine/Poly(o -Aminobenzoic acid)-Membrane-Modified Platinum Electrode for the Determination of Hydrogen Peroxide

CHINESE JOURNAL OF CHEMISTRY, Issue 11 2006
Ming-Yu Tang
Abstract The third generation amperometric biosensor for the determination of hydrogen peroxide (H2O2) has been described. For the fabrication of biosensor, o -aminobenzoic acid (oABA) was first electropolymerized on the surface of platinum (Pt) electrode as an electrostatic repulsion layer to reject interferences. Horseradish peroxidase (HRP) absorbed by nano-scaled particulate gold (nano-Au) was immobilized on the electrode modified with polymerized o -aminobenzoic acid (poABA) with L -cysteine as a linker to prepare a biosensor for the detection of H2O2. Amperometric detection of H2O2 was realized at a potential of +20 mV versus SCE. The resulting biosensor exhibited fast response, excellent reproducibility and sensibility, expanded linear range and low interferences. Temperature and pH dependence and stability of the sensor were investigated. The optimal sensor gave a linear response in the range of 2.99×10,6 to 3.55×10,3 mol·L,1 to H2O2 with a sensibility of 0.0177 A·L,1·mol,1 and a detection limit (S/N=3) of 4.3×10,7 mol·L,1. The biosensor demonstrated a 95% response within less than 10 s. [source]

Electrochemical Study of Anionic Ferrocene Derivatives Intercalated in Layered Double Hydroxides: Application to Glucose Amperometric Biosensors

ELECTROANALYSIS, Issue 3-5 2009
Christine Mousty
Abstract Layered double hydroxides (Zn2Cr(OH)6X,nH2O LDH) containing (3-sulfopropyl)ferrocene-carboxylate (FcPSO3) and 1,1,-bis(3-sulfopropyl)ferrocene-carboxylate (Fc(PSO3)2) as interlayer anions (X) have been prepared by the co-precipitation method and characterized by PXRD, FTIR, SEM and XPS. The electrochemical behavior of these hybrid materials has been evaluated by cyclic voltammetry. A new amperometric biosensor based on the immobilization of glucose oxidase in ZnCr-FcPSO3 hybrid material was presented, the intercalated anions playing the role of mediators that shuttle electrons between the FAD centers in the enzyme and the electrode surface. The performance of the resulting biosensor for glucose determination under anaerobic conditions was evaluated by chronoamperometry at 0.5,V. The sensitivity (65,mA M,1 cm,2) determined in the concentration range 10,25,,M is higher than sensitivities reported for other glucose biosensors based on LDH host matrices. [source]

Amperometric Biosensors for Detection of Sugars Based on the Electrical Wiring of Different Pyranose Oxidases and Pyranose Dehydrogenases with Osmium Redox Polymer on Graphite Electrodes

ELECTROANALYSIS, Issue 2-3 2007
Federico Tasca
Abstract Electrical wiring of different types of pyranose oxidase (P2O) (fungal wild type, recombinant wild type with a hexa-histidine tag, mutant form E542K with a hexa-histidine tag) from Trametes multicolor, and recombinant P2O from Coriolus sp. overexpressed in Escherichia coli as well as of pyranose dehydrogenase (PDH) from Agaricus meleagris and Agaricus xanthoderma with an osmium redox polymer (poly(1-vinylimidazole)12 -[Os(4,4,-dimethyl-2,2,-dipyridyl)2Cl2]2+/+) on graphite electrodes was carried out. After optimization studies using glucose as substrate, the biosensors, which showed the best characteristics in terms of linear range, detection limit and sensitivity were selected, viz. wild type P2O from T. multicolor and PDH from A. meleagris. These two enzymes were used and investigated for their selectivity for a number of different sugars. [source]

Amperometric Biosensors Based on Choline Oxidase Entrapped in Polyacrylamide Microgels

ELECTROANALYSIS, Issue 2-3 2007
López, M. Sánchez-Paniagua
Abstract A choline amperometric biosensor has been designed using as biological component choline oxidase (ChOx) entrapped in polyacrylamide microgels. The working electrode was prepared by holding the enzyme loaded microgels on a platinum electrode by a dialysis membrane. It was found that the optimum microgel cross-linking required to retain ChOx and to allow the diffusion of choline was 7.0%. The response of the biosensor was optimized in relation to pH, temperature and working potential and the following optimal values were obtained: pH,9.0, temperature range between 20 and 30,°C, and potential +0.6,V. Under optimal conditions the sensitivity for choline was 17.45,mA M,1 cm,2, the detection limit 8,,M, and the response linear range from 2×10,5 M to 2×10,4 M. This biosensor has been also used as a nicotine detector due to the inhibition of the catalytic activity of choline oxidase by this compound. Moreover, the simultaneous entrapment of a second enzyme, acetylcholinesterase (AChE), in the microgels makes the biosensor sensible to acetylcholine. [source]

Composite Multienzyme Amperometric Biosensors for an Improved Detection of Phenolic Compounds

ELECTROANALYSIS, Issue 22 2003
B. Serra
Abstract A biosensor design, in which glucose oxidase and peroxidase are coimmobilized by simple physical inclusion into the bulk of graphite-Teflon pellets, is reported for the detection of phenolic compounds. This design allows the "in situ" generation of the H2O2 needed for the enzyme reaction with the phenolic compounds, which avoids several problems detected in the performance of single peroxidase biosensors as a consequence of the presence of a high H2O2 concentration. So, a much lower surface fouling was found at the GOD-HRP biosensor in comparison with a graphite-Teflon-HRP electrode, suggesting that the controlled generation of H2O2 makes more difficult the formation of polymers from the enzyme reaction products. The construction of trienzyme biosensors, in which GOD, HRP and tyrosinase were coimmobilized into the graphite-Teflon matrix is also reported, and their performance was compared with that of GOD-HRP bienzyme electrodes. The practical applicability of the composite multienzyme amperometric biosensors was evaluated by the estimation of the phenolic compounds content in waste waters from a refinery, and the results were compared with those obtained by using a colorimetric official method based on the reaction with 4-aminoantipyrine. [source]

New Strategy for Dehydrogenase Amperometric Biosensors Using Surfactant to Enhance the Sensitivity of Diaphorase/Ferrocene Modified Carbon Paste Electrodes for Electrocatalytic Oxidation of NADH

ELECTROANALYSIS, Issue 13 2003
César Ramírez-Molina
Abstract A carbon paste electrode (CPE) modified with diaphorase (DAP) and ferrocene (FcH) has been developed for determination of NADH at low working potential. The sensitivity and operational stability, towards the detection of the reduced form of the nicotinamide adenine dinucleotide (NADH) in flow injection analysis (FIA), were greatly improved (5 times) upon adding Tween 20 into the electrode matrix. The magnitude of the amperometric signal was dependent on DAP, FcH and surfactant loading, into the modified carbon paste electrode. A rapid and repeatable response was observed to the variation of NADH concentration in the vicinity of the electrode surface. Such advantages of the DAP/FcH/Tween 20 modified carbon paste were successfully used in the construction of L -lactate dehydrogenase modified electrodes. The use of this new approach can be generalized to other dehydrogenases and represents a decisive step for a versatile preparation method of amperometric biosensors. [source]

A New Polyphenol Oxidase Biosensor Mediated by Azure B in Laponite Clay Matrix

ELECTROANALYSIS, Issue 19 2003
Dan Shan
Abstract Amperometric biosensor based on the entrapment of polyphenol oxidase within a laponite clay coating and cross-linked by glutaraldehyde is described for catechol detection. Laponite provides a hydrophilic enzyme surrounding increasing the long term stability of the biosensor compared to the corresponding biosensors obtained by chemical cross-linking of PPO with glutaraldehyde. Azure B, a cationic dye exchanged within the clay matrix, is used as an electron shuttle allowing the mediated detection of phenol derivatives at ,0.05 V. The detection limits obtained with the optimized biosensor configuration for catechol, p -cresol and phenol are 1, 1 and 17,nM, respectively. [source]

Development of Novel Glucose and Pyruvate Biosensors at Poly(Neutral Red) Modified Carbon Film Electrodes.

ELECTROANALYSIS, Issue 8 2006
Application to Natural Samples
Abstract Amperometric biosensors based on the corresponding oxidase enzyme with poly(neutral red) redox mediator have been developed for the determination of glucose and pyruvate. The enzymes have been immobilized on top of poly(neutral red) modified carbon film electrodes with glutaraldehyde as the cross-linking agent. The biosensors were characterized by cyclic voltammetry and by electrochemical impedance spectroscopy. The glucose biosensor exhibited a linear response in the range 90,,M to 1.8,mM with a detection limit of 22,,M and the pyruvate biosensor in the range 90 to 600,,M with a detection limit of 34,,M. The relative standard deviations were found to be 2.1% (n=3) and 2.8% (n=4) respectively. The interference effects of various compounds were also studied. The glucose content of several types of wine and the amount of pyruvate in onion and garlic were determined and the results were compared with those obtained by standard spectrophotometric methods. [source]

Electrochemical Study of Anionic Ferrocene Derivatives Intercalated in Layered Double Hydroxides: Application to Glucose Amperometric Biosensors

An Organic Sol-Gel Film as Modifier to Construct Biosensor

ELECTROANALYSIS, Issue 2 2009
Jian-Feng Wu
Abstract A new amperometric biosensor for hydrogen peroxide (H2O2) was developed by adsorbing hemoglobin (Hb) on an organic sol-gel film. The organic sol-gel was prepared using resorcinol and formaldehyde as monomers. This sol-gel film shows a biocompatible microenvironment for retaining the native activity of the adsorbed Hb. The direct electron transfer between Hb and electrode is achieved. Hb adsorbed on the film shows an enzyme-like catalytic activity for the reduction of H2O2. The reduction peak currents are proportional linearly to the concentration of hydrogen peroxide in the range of 6×10,8 to 3.6×10,6,M, with a detection limit of 2.4×10,8,M (S/N=3). This research enlarges the applications of organic sol-gel materials in biosensor field. [source]

Gas Diffusion Electrodes for Use in an Amperometric Enzyme Biosensor

ELECTROANALYSIS, Issue 21 2008
Martin Hämmerle
Abstract The preparation of gas diffusion electrodes and their use in an amperometric enzyme biosensor for the direct detection of a gaseous analyte is described. The gas diffusion electrodes are prepared by covering a PTFE membrane (thickness 250,,m, pore size 2,,m, porosity 35%) with gold, platinum, or a graphite/PTFE mixture. Gold and platinum are deposited by e-beam sputtering, whereas the graphite/PTFE layer is prepared by vacuum filtration of a respective aqueous suspension. These gas diffusion electrodes are exemplarily implemented as working electrodes in an amperometric biosensor for gaseous formaldehyde containing NAD-dependent formaldehyde dehydrogenase from P. putida [EC. 1.2.1.46] as enzyme and 1,2-naphthoquinone-4-sulfonic acid as electrochemical mediator. The resulting sensors are compared with regard to background current, signal noise, linear range, sensitivity, and detection limit. In this respect, sensors with gold or graphite/PTFE covered membranes outclass ones with platinum for this particular analyte and sensor configuration. [source]

Amperometric L -Lactate Biosensor Based on Gold Nanoparticles

ELECTROANALYSIS, Issue 7-8 2007
Bikash, Kumar Jena
Abstract A novel amperometric biosensor for the sensing of L -lactate is developed using L -lactate dehydrogenase (LDH) and hydroxylamine enlarged gold nanoparticles (GNPs). LDH and GNPs have been integrated with the sol,gel 3-D silicate network derived from 3-(mercaptopropyl)trimethoxysilane (MPTS). The biosensing of L -lactate is based on the electrocatalytic determination of enzymatically generated NADH by GNPs of the integrated assembly. The GNPs on the network efficiently catalyze the oxidation of NADH at ,0.065,V, which is ca. 915,mV less positive than on the bulk Au electrode. The biosensor was characterized in terms of the effects of enzyme loading, solution pH, and cofactor concentration. The integrated biosensor was successfully utilized for the amperometric sensing of L -lactate and it shows excellent sensitivity with a detection limit of 100,nM. The common interfering electroactive compounds in the biological system do not interfere the amperometric measurement of L -lactate. This biosensor linearly responds to L -lactate in the range of 0,0.8,mM and the sensitivity of the electrode was 0.446,nA/nM. Excellent reproducibility, long time storage and operational stability have been achieved. [source]

Amperometric Biosensors Based on Choline Oxidase Entrapped in Polyacrylamide Microgels

Gold Nanoparticle-Based Mediatorless Biosensor Prepared on Microporous Electrode

ELECTROANALYSIS, Issue 3 2006
Fenghua Zhang
Abstract A mediatorless biosensor was fabricated with a double-sided microporous gold electrode by successively immobilizing a mixed self-assembled monolayer (SAM) comprising carboxylic-acid- and thiol-terminated thiolate (dl -thiorphan and 1,8-octanedithiol), glucose oxidase (GOx) and finally gold nanoparticle (Au NP) on one working side. The double-sided microporous gold electrodes were formed by plasma sputtering of gold on a porous nylon substrate, yielding a face-to-face type two-electrode electrochemical cell. While the straight chain molecule 1,8-octanedithiol forms a dense insulating monolayer, the side armed dl -thiorphan forms a low density layer for the diffusion of redox couples to the electrode surface. The mixed SAM not only provided the linking functional groups for both enzyme and Au NP but also resulted in the appropriately spaced monolayer for direct electron tansfer (ET) process from the center of the redox enzyme to the electrode surface. After covalently immobilizing GOx onto the carboxylic-acid-terminated monolayer, Au NP was easily immobilized to both enzyme and nearby thiols by simple dispensing of the colloidal gold solution. It was observed that the resulting amperometric biosensor exhibited quantitatively the same response to glucose in the presence and in the absence of dissolved oxygen, which evidence that the Au NPs immobilized on and around the GOx promote direct ET from the enzymes to the electrode, assuming the role of a common redox mediator. [source]

A Microbial Biosensor for p -Nitrophenol Using Arthrobacter Sp.

ELECTROANALYSIS, Issue 14 2003
Yu Lei
Abstract This article reports the construction, optimization of performance variables and analytical characterization of a sensitive and selective microbial amperometric biosensor for measurement of p -nitrophenol (PNP), a U.S. Environmental Agency priority pollutant. The biosensor consisted of PNP-degrading/oxidizing bacteria Arthrobacter sp. JS443 as biological sensing element and a dissolved oxygen electrode as the transducer. The best sensitivity and response time were obtained using a sensor constructed with 1.2,mg dry wt. of cells and operating in pH,7.5, 50,mM citrate-phosphate buffer. Using these conditions, the biosensor was able to measure as low as 28,ppb (0.2,,M) of PNP selectively without interference from structurally similar compounds, such as phenol, nitrophenols and chlorophenols. The service life of the microbial biosensor is around 5,days when stored in the operating buffer at 4,°C. The applicability to lake water is demonstrated. [source]

Noncovalent Assembly of Picket-Fence Porphyrins on Nitrogen-Doped Carbon Nanotubes for Highly Efficient Catalysis and Biosensing

CHEMISTRY - A EUROPEAN JOURNAL, Issue 13 2010
Wenwen Tu
Abstract A water-insoluble picket-fence porphyrin was first assembled on nitrogen-doped multiwalled carbon nanotubes (CNx MWNTs) through FeN coordination for highly efficient catalysis and biosensing. Scanning electron micrographs, Raman spectra, X-ray photoelectron spectra, UV/Vis absorption spectra, and electrochemical impedance spectra were employed to characterize this novel nanocomposite. By using electrochemical methods on the porphyrin at low potential in neutral aqueous solution, the presence of CNx MWNTs led to the direct formation of a high-valent iron(IV),porphyrin unit, which produced excellent catalytic activity toward the oxidation of sulfite ions. By using sulfite ions, a widely used versatile additive and preservative in the food and beverage industries, as a model, a highly sensitive amperometric biosensor was proposed. The biosensor showed a linear range of four orders of magnitude from 8.0×10,7 to 4.9×10,3,mol,L,1 and a detection limit of 3.5×10,7,mol,L,1 due to the highly efficient catalysis of the nanocomposite. The designed platform and method had good analytical performance and could be successfully applied in the determination of sulfite ions in beverages. The direct noncovalent assembly of porphyrin on CNx MWNTs provided a facile way to design novel biofunctional materials for biosensing and photovoltaic devices. [source]

Effect of Enzyme and Cofactor Immobilization on the Response of Ethanol Oxidation in Zirconium Phosphate Modified Biosensors

ELECTROANALYSIS, Issue 10 2010
Mitk'El
Abstract Two different self-contained ethanol amperometric biosensors incorporating layered [Ru(phend)2bpy]2+ -intercalated zirconium phosphate (ZrP) as the mediator as well as yeast -alcohol dehydrogenase (y- ADH) and its cofactor nicotinamide adenine dinucleotide (NAD+) were constructed to improve upon a design previously reported where only this mediator was immobilized in the surface of a modified electrode. In the first biosensor, a [Ru(phend)2bpy]2+ -intercalated ZrP modified carbon paste electrode (CPE) was improved by immobilizing in its surface both y- ADH and NAD+ using quaternized Nafion membrane. In the second biosensor, a glassy carbon electrode was modified with [Ru(phend)2bpy]2+ -intercalated ZrP, y- ADH, and NAD+ using Nafion as the holding matrix. Calibration plots for ethanol sensing were constructed in the presence and absence of ZrP. In the absence of ZrP in the surface of the modified glassy carbon electrode, leaching of ADH was observed as detected by UV-vis spectrophotometry. Ethanol sensing was also tested in the presence and absence of ascorbate to measure the selectivity of the sensor for ethanol. These two ethanol biosensors were compared to a previously reported one where the y -ADH and the NAD+ were in solution, not immobilized. [source]

Chitosan-Glutamate Oxidase Gels: Synthesis, Characterization, and Glutamate Determination

ELECTROANALYSIS, Issue 23 2005
Maogen Zhang
Abstract The biopolymer chitosan (CHIT) was chemically modified with glutaric dialdehyde (GDI) and used for the covalent immobilization of enzyme glutamate oxidase (GmOx). The relationships between the loaded, retained, and active units of GmOx in the CHIT-GDI-GmOx gels were determined by electrochemical assays. The latter indicated that on average ca. 95% of the GmOx was retained in the CHIT-GDI matrix that was loaded with 0.10,3.0 units of the enzyme. The maximum activity of the GmOx immobilized in the gels corresponded to ca. 5% of the activity of the free enzyme. Platinum electrodes coated with CHIT-GDI-GmOx gels (films) were used as amperometric biosensors for glutamate. Such biosensors displayed good operational and long-term stability (at least 11,h and 100 days, respectively) in conjunction with low detection limit of 0.10,,M glutamate (S/N=3), linear range up to 0.5,mM (R2=0.991), sensitivity of 100 mA M,1 cm,2, and short response time (t90%=2,s). This demonstrated an efficient signal transduction in the Pt/CHIT-GDI-GmOx+glutamate system. The CHIT-GDI-GmOx gels constitute a new biosensing element for the development of glutamate biosensors. [source]

Carbon-Nanotube Based Electrochemical Biosensors: A Review

ELECTROANALYSIS, Issue 1 2005
Joseph Wang
Abstract This review addresses recent advances in carbon-nanotubes (CNT) based electrochemical biosensors. The unique chemical and physical properties of CNT have paved the way to new and improved sensing devices, in general, and electrochemical biosensors, in particular. CNT-based electrochemical transducers offer substantial improvements in the performance of amperometric enzyme electrodes, immunosensors and nucleic-acid sensing devices. The greatly enhanced electrochemical reactivity of hydrogen peroxide and NADH at CNT-modified electrodes makes these nanomaterials extremely attractive for numerous oxidase- and dehydrogenase-based amperometric biosensors. Aligned CNT "forests" can act as molecular wires to allow efficient electron transfer between the underlying electrode and the redox centers of enzymes. Bioaffinity devices utilizing enzyme tags can greatly benefit from the enhanced response of the biocatalytic-reaction product at the CNT transducer and from CNT amplification platforms carrying multiple tags. Common designs of CNT-based biosensors are discussed, along with practical examples of such devices. The successful realization of CNT-based biosensors requires proper control of their chemical and physical properties, as well as their functionalization and surface immobilization. [source]

Composite Multienzyme Amperometric Biosensors for an Improved Detection of Phenolic Compounds

New Strategy for Dehydrogenase Amperometric Biosensors Using Surfactant to Enhance the Sensitivity of Diaphorase/Ferrocene Modified Carbon Paste Electrodes for Electrocatalytic Oxidation of NADH

Release of ATP in the central nervous system during systemic inflammation: real-time measurement in the hypothalamus of conscious rabbits

THE JOURNAL OF PHYSIOLOGY, Issue 1 2007
Alexander V. Gourine
Receptors for extracellular ATP (both ionotropic and metabotropic) are widely expressed in the CNS both in neurones and glia. ATP can modulate neuronal activity in many parts of the brain and contributes to the central nervous control of several physiological functions. Here we show that during the systemic inflammatory response the extracellular concentrations of ATP increase in the anterior hypothalamus and this has a profound effect on the development of the thermoregulatory febrile response. In conscious rabbits we measured ATP release in real time with novel amperometric biosensors and monitored a marked increase in the concentration of ATP (4.0 ± 0.7 ,m) in the anterior hypothalamus in response to intravenous injection of bacterial endotoxin , lipopolysaccharide (LPS). No ATP release was observed in the posterior hypothalamus. The release of ATP coincided with the development of the initial phase of the febrile response, starting 18 ± 2 min and reaching its peak 45 ± 2 min after LPS injection. Application of the ATP receptor antagonists pyridoxal-5,-phosphate-6-azophenyl-2,,4,-disulphonic acid, Brilliant Blue G or periodate oxidized ATP dialdehyde to the site of ATP release in the anterior hypothalamus markedly augmented and prolonged the febrile response. These data indicate that during the development of the systemic inflammation, ATP is released in the anterior hypothalamus to limit the magnitude and duration of fever. This release may also have a profound effect on the hypothalamic control of other physiological functions in which ATP and related purines have been implicated to play modulatory roles, such as food intake, hormone secretion, cardiovascular activity and sleep. [source]

Charge Transport in Redox Polyelectrolyte Multilayer Films: The Dramatic Effects of Outmost Layer and Solution Ionic Strength

CHEMPHYSCHEM, Issue 13 2010
Dr. Mario Tagliazucchi
Abstract The redox switching kinetics, that is, charge transfer and transport in layer-by-layer-deposited electroactive polyelectrolyte multilayers is systematically studied with variable-scan-rate cyclic voltammetry. The experiments are performed with films finished in the redox polycation (an osmium pyridine,bipyridine derivatized polyallylamine, PAH-Os) and the polyanion (polyvinyl sulfonate, PVS), in solutions of different electrolyte concentrations. A modified diffusion model is developed to account for the experimentally observed dependence of the average peak potential with the scan rate. This model is able to describe both the redox peak potential and the current, providing information on the electron-transfer rate constants and the diffusion coefficient for the electron-hopping mechanism. While the former does not vary with the ionic strength or the nature of the outmost layer, polyanion-capped films present an electron-hopping diffusion coefficient at low ionic strength that is three orders of magnitude smaller than that for PAH-Os-capped films. The effect is offset at high ionic strength. We discuss the possible causes of the effect and the important consequences for electrochemical devices built by layer-by-layer self-assembly, such as amperometric biosensors or electrochromic devices. [source]