Amperometric Glucose Biosensor Based on Glucose Oxidase Encapsulated in Carbon Nanotube–Titania–Nafion Composite Film on Platinized Glassy Carbon Electrode

A highly sensitive and selective glucose biosensor has been developed based on immobilization of glucose oxidase within mesoporous carbon nanotube–titania–Nafion composite film coated on a platinized glassy carbon electrode. Synergistic electrocatalytic activity of carbon nanotubes and electrodeposited platinum nanoparticles on electrode surface resulted in an efficient reduction of hydrogen peroxide, allowing the sensitive and selective quantitation of glucose by the direct reduction of enzymatically‐liberated hydrogen peroxide at ?0.1 V versus Ag/AgCl (3 M NaCl) without a mediator. The present biosensor responded linearly to glucose in the wide concentration range from 5.0×10^?5 to 5.0×10^?3 M with a good sensitivity of 154 mA M^?1cm^?2. Due to the mesoporous nature of CNT–titania–Nafion composite film, the present biosensor exhibited very fast response time within 2 s. In addition, the present biosensor did not show any interference from large excess of ascorbic acid and uric acid.     

Flow Injection Amperometric Determination of Hydrogen Peroxide at Low Level in Aqueous Solution

Abstract

A method is proposed for the flow-injection amperometric determination of hydrogen peroxide. Iodine is generated, by injecting hydrogen peroxide solution into an eluent 0.2 M in potassium iodide and 1 Min sulphuric acid and 5×10^?3M in Mo(VI) and is monitored at a platinum electrode that is being held at 0.1 V versus SCE. the rectilinearity range is from 10^?3?10^?6 M and the method is simple, accurate and compared favourably with the titrimetric method involving starch as indicator.     

Amperometric Biosensors Based on Platinum Nanowires

Abstract

Platinum nanowires (PtNW) were prepared by an electrodeposition strategy using nanopore alumina template. The nanowires prepared were dispersed in chitosan (CHIT) solution and stably immobilized onto the surface of glassy carbon electrode (GCE). The electrochemical behavior of PtNW‐modified electrode and its application to the electrocatalytic reduction of hydrogen peroxide (H₂O₂) are investigated. The modified electrode allows low potential detection of hydrogen peroxide with high sensitivity and fast response time. As an application example, the glucose oxidase was immobilized onto the surface of PtNW‐modified electrode through cross‐linking by glutaric dialdehyde. The detection of glucose was performed in phosphate buffer at –0.2 V. The resulting glucose biosensor exhibited a short response time (<8 s), with a linear range of 10^?5?10^?2 M and detection limit of 5×10^?6 M.     

Grape tissue-based electrochemical sensor for the determination of hydrogen peroxide

The use of grape tissue as a source of catalase for the determination of hydrogen peroxide is reported. A slice of grape tissue attached to the membrane of a Clark-type oxgen sensor was used to monitor the oxidation of hydrogen peroxide by catalase. At the steady state, the sensor responds linearly to hydrogen peroxide in the concentration range 1 × 10^?5–5 × 10^?4 M. The response time (T₉₀) was of the order of 1 min for this sensor. No interference was observed from ethanol, amino acids, glucose and lactic acid. The long-term stability of the grape tissue sensor was much better than previously reported immobilized enzyme and liver tissue-based hydrogen peroxide sensors.     

Glucose sensors based on enzyme immobilization onto biocompatible membranes obtained by radiation-induced polymerization

Amperometric glucose biosensors based on glucose oxidase immobilized onto poly(2-hydroxyethylmethacrylate) membranes obtained by γ radiation-induced polymerization were constructed. In a threeelectrode configuration, smooth or platinized platinum electrodes with different shapes were used, in order to detect the amount of hydrogen peroxide produced in the glucose oxidation. A saturated calomel electrode and a platinum foil were used as a reference and counterelectrode, respectively. The biocompatible obtained sensors were characterized as regards the temperature effect, the response, and lifetime. The determination of glucose in standard solutions was carried out, and linear calibration curves were obtained. Depending on the electrode configuration, the sensor had a response time of 1–4 min, and the measuring range extended from 5 × 10^?5 to 4 × 10^?3M.     

Amperometric aspartate electrode

An amperometric enzyme electrode for L-aspartate determination was developed. The probe consisted of a platinum electrode which senses hydrogen peroxide produced from the reactions catalyzed by two enzymes co-immobilized on a preactivated polymeric membrane, α-Ketoglutarate in the presence of L-aspartate was transaminated to L-glutamate by aspartate aminotransferase and the glutamate produced was oxidized by glutamate oxidase, with concomitant production of hydrogen peroxide. Additional protective membranes eliminated interferences from glutamate and most electroactive compounds. The response curve of the probe was linear over the concentration range 1.0 × 10^?6 M to 2.0 × 10^?4 M aspartate and was useful for at least two months. Aspartic acid in some pharmaceutical products was determined and the results correlated well with a liquid chromatographic reference method and the manufacturer's specification.     

Catalyzed Determination of Glucose with a Mimic Enzyme Constructed of Bis‐[‐6‐O‐(‐β‐ethyloic‐butanedioic Acid‐1,4‐ester‐4‐)]β‐Cyclodextrin · Fe3+

Abstract

Catalyzed determination of glucose with mimic glucose oxidase is constructed by the reaction of β‐cyclodextrin, maleic anhydride, and chloroacetic acid with iron trichloride in hydrogen peroxide. The method is simple and convenient, and sensitivity and repeatability are ideal. Beer's law is obeyed in a concentration range of 30–197 µg · ml^?1 glucose with an excellent correlation coefficient (r=0.9994), while the detection limit is 4.10 µg · ml^?1, the RSD is 0.98% (n=8). The recovery of sample is 95.8–103.1%.     

Amperometric Glucose Biosensor Based on the Deposition of Copper and Glucose Oxidase onto Glassy Carbon Transducer

ABSTRACT

The performance of a first generation glucose amperometric biosensor based on the entrapment of glucose oxidase (GOx) within a net of copper electrodeposited onto activated glassy carbon electrode, is described. The copper electrodeposited offers an efficient electrocatalytic activity towards the reduction of enzymatically-liberated hydrogen peroxide, allowing for a fast and sensitive glucose quantification. The influence of the electrodeposition conditions (pH, potential, time, copper salt and enzyme concentrations) on the response of the bioelectrode was evaluated from the amperometric signals of hydrogen peroxide and glucose. The combination of copper electrodeposition with a nation membrane allows an excellent selectivity towards easily oxidizable compounds such as uric and ascorbic acids at an operating potential of -0.050 V. The response is linear up to 2.0 × 10^?2 M glucose, the detection limit being 1.2 × 10^?3 M.     

Flow injection analysis for glucose by the combined use of an immobilized glucose oxidase reactor and a peroxidase electrode

The amperometric peroxidase electrode measures hexacyanoferrate(III), produced by hydrogen peroxide, which is generated by injecting a 2μl sample into a reactor of immobilized glucose oxidase covalently bound to silica gel. The peak current is linearly related to the glucose concentration in the range 0.05–10 g l^?1; sample throughput is about 100 h^?1. Ascorbic acid (? 0.5 mM) does not interfere.     

Electrode Hybride Pour la Determination de Phosphates et de Polyphosphates. Application aux Problemes Lies a l'Environnement

Abstract

The determination of phosphates and polyphosphates has been effected using an hybrid electrode, which consists of a glucose oxydase enzymic membrane and a Solanum tuberosum tissue slice. This membrane, rich in acid phosphatase, catalyses the glucose-6-phosphate hydrolysis. This reaction is quantitatively inhibited by phosphate. Several factors involved in the electrode response, like substrate concentration, pH, ionic strength and type of buffer are discussed in detail. At a 4.10^?4 M glucose-6-phosphate concentration, the linear ranges of phosphates and polyphosphates are, respectively, 6.10^?5 M to 1.6.10^?3 M and 3.10^?5 M to 1.10^?3 M. The urinary phosphate contents determinated by this biosensor are in good agrement with those obtained by usual spectrophotometric techniques.     

Immobilization of Horseradish Peroxidase on a Biocompatible Titania Layer–Modified Gold Electrode for the Detection of Hydrogen Peroxide

Abstract

A procedure for fabricating an enzyme electrode has been described based on the effective immobilization of horseradish peroxidase to an ultrathin titania layer–modified self‐assembled gold electrode. The resulting electrode exhibits excellent electrocatalytical activity to hydrogen peroxide in the presence of hydroquinone as a mediator. The analytical conditions were studied in detail by using an amperometric method. Under the optimized conditions, a detection limit of 7.1×10^?7 mol l^?1 and a linear response to hydrogen peroxide that ranged from 1×10^?6 mol l^?1 to 7.6×10^?4 mol l^?1 were obtained. The reproducibility and stability were examined with satisfactory results.     

On the Effect of Hydrogen Peroxide on the Flow‐Injection Determination of Platinum Based on Luminol Chemiluminescent Reaction

Abstract

A flow‐injection chemiluminescent (CL) method for the determination of trace amounts of Pt(IV) based on the oxidation reaction of luminol in alkaline solution is proposed. The effect of Pt(IV) on the oxidation of luminol was studied in the absence and in the presence of hydrogen peroxide. The positive effect of hydrogen peroxide as well as chloride ions on the sensitivity of measurements was observed. The developed method is characterized by a low limit of detection of Pt (LOD=0.06 ng mL^?1) and good reproducibility (RSD=2.2%). The addition of hydrogen peroxide to the reaction medium resulted in decreasing of platinum detection limit to 0.03 ng mL^?1.     

Amperometric determination of glucose in undiluted food samples

Glucose oxidase is immobilized onto a cellulose acetate membrane by glutaraldehyde linkage, and the membrane is used to cover the platinum electrode of a hydrogen peroxide sensor. A silanized polycarbonate membrane then covers the enzyme layer, and extends the linear calibration range to higher concentrations. The sensor, when incorporated into a flow-injection system, allows the determination of glucose at levels up to 1 M in soft drinks at a rate of 60 samples h^?1 without sample dilution.     

Electrochemical Codeposition of Platinum and Molybdenum Oxides: Formation of Composite Films with Distinct Electrocatalytic Activity for Hydrogen Peroxide Detection

The electrochemical properties of gold electrode surfaces modified by molybdenum oxide films intercalated with platinum microparticles have been described. The incorporation of Pt microparticles at the oxide film was characterized by PIXE (particle induced X‐ray emission) spectroscopy. The modified electrode showed electrochemical activity at around ?0.5 V in 50 mmol L^?1 Na₂SO₄ supporting electrolyte (pH 3), corresponding to the reduction of protons at platinum sites and further transfer of hydrogen atoms to form reduced molybdenum oxides (bronzes). At 0.1 V, the MoO₃ / Pt electrode showed a better performance for hydrogen peroxide oxidation than on platinized gold electrodes. The solution pH has a marked effect on the voltammetric profile and best responses for hydrogen peroxide were obtained at the 5.0 to 6.0 pH range. The activation of the electrode by polarization at negative potentials was also studied and a mechanism by which more platinum sites are available as a consequence of this process was proposed. Calibration plots for hydrogen peroxide were highly linear (r=0.9989) in the 0.2 to 1.6 mmol L^?1 concentration range, with a relative standard deviation (RSD)<1%.     

Amperometric Glucose Biosensor Based on Platinum Nanoparticles Combined Aligned Carbon Nanotubes Electrode

A sensitive amperometric glucose biosensor based on platinum nanoparticles (PtNPs) combined aligned carbon nanotubes (ACNTs) electrode was investigated. PtNPs which can enhance the electrocatalytic activity of the electrode for electrooxidating hydrogen peroxide by enzymatic reaction were electrocrystallized on 4‐aminobenzene monolayer‐grafted ACNTs electrode by potential‐step method. These PtNPs combined ACNTs' (PtNPs/ACNTs) surfaces were characterized by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The highly dispersed PtNPs on ACNTs can be obtained. The enzyme electrode exhibits excellent response performance to glucose with linear range from 1×10^?5–7×10^?3 mol L^?1 and fast response time within 5 s. Furthermore, this glucose biosensor also has good reproducibility. It is demonstrated that the PtNPs/ACNTs electrode with high electrocatalytic activity is a suitable basic electrode for preparing enzyme electrodes.     

Study On The Catalytic Reaction Of β-Cd-Hemin Using 2, 3, 4-Trichlorophenol As Substrate And Analytic Application

ABSTRACT|The catalytic activity of various mimetic enzymes instead of the peroxidase have been investigated by 4-aminoantipyrine (4-AAP) and 2, 3, 4-trichlorophenol (TCP) to form a dye utilizing hydrogen peroxide as hydrogen acceptor. The different Chlorophenolic derivatives, which act as a substrate in β-CD-hemin-H₂O₂-4-AAP catalytic reaction, have been systematically studied.|Meanwhile, the relationship of structure-effect for the β-CD-hemin as catalyst, and chlorphenols as substrate has been respectively discussed. The mechanism of catalytic reaction has been investigated. The results showed that β-CD-hemin was the best mimetic enzyme for peroxidase among those tested and TCP was a good substrate for the determination of hydrogen peroxide with β-CD-hemin. The method for the determination of hydrogen peroxide was proposed using 4-AAP-TCP system with β-CD-hemin as catalyst. A linear calibration graph was obtained over the H₂O₂ concentration of 4.8×10-^?8-7.7×10-^?5M, and the relative standard deviation at a H₂O₂ concentration of 2.8×10-^?5M was 2.5%. The apparent molar absorptivity of the chromogenic reaction for H₂O₂ was 1.54× 10⁴ L.mol-^?1.cm^?1. Satisfactory results were obtained in the determination of H₂O₂ in synthetic samples by this method.

Also, the method was coupled with the glucose oxidation reaction to determination glucose in human serum.     

Amperometric Biosensor for Adenosine-5′-Triphosphate Based on a Platinum-Dispersed Carbon Paste Enzyme Electrode

Abstract

A new amperometric biosensor for adenosine-5′-triphosphate (ATP) was designed using a platinum-dispersed carbon paste into which glycerol kinase and glycerol-3-phosphate oxidase were incorporated. The biosensor is based on the detection of hydrogen peroxide produced by the enzymatic reaction of ATP with glycerol and the subsequent oxidation of glycerol-3-phosphate. The use of the platinum-dispersed carbon paste electrode lowered the oxidation potential for hydrogen peroxide, permitting the sensitive detection of ATP at 0.4 V vs. Ag/AgCl. A linear response to ATP was observed in the concentration range of 1 x 10^?5 to 2.5 x 10^?3 M.

     

Micro-Enzyme Electrode Prepared on Platinized Platinum

Abstract

Micro-enzyme electrode with high performance was fabricated on a micro-platinum electrode surface (diameter = 50 ～ 200 μm) by taking advantage of very huge surface of platinized platinum. Glucose oxidase was incorporated into the micropores of platinum particle by immersing a micro-platinized platinum electrode in a solution containing glucose oxidase. The micro-enzyme electrode for glucose demonstrated high performance such as high sensitivity (the least detectable limit : 5 × 10^?7 M), fast responsiveness (100 % response : 3 sec), and accuracy (C.V. = 1.4 %) in the repeated determination of glucose.     

Construction and Characterization of a Beet Stem Based Biosensor for Oxalate

Abstract

This report describes the construction and characterization of an oxalate-sensing electrode. The electrode is based on the incorporation of ground beet stem into the graphite paste of a graphite paste electrode. The hydrogen peroxide generated by enzymatic degradation of oxalate is monitored at a working voltage of 0.900 V vs SCE. All measurements were conducted in a succinic acid/EDTA buffer at pH 4.00. Under these conditions, the electrodes exhibit reproducible responses to oxalate. The lower limit of oxalate detection was less than 1.03 × 10^?4 M. The time to achieve a steady state response after exposure to a step change in oxalate concentration in solution is less than one minute. The magnitude of response to oxalate over the oxalate concentrations studied varies among several electrode tested as does the degree of linearity of response. An electrode studied still exhibited analytically useful responses to oxalate on the 15th day of its use. The beet stem-based electrodes display little response to glycolic acid, glucose, DL-valine, or pyruvate.     

Flow-Injection Determination of Glucose by a Photoinduced Chemiluminescent Reaction

Abstract

A flow-injection procedure for the photochemical determination of glucose has been developed. The method is based on the photo-oxidation of glucose sensitized by 9,10-anthraquinone-2.6-disulfonate (disodium salt). The hydrogen peroxide formed in the photochemical reaction was measured by means of the chemiluminescent reaction with luminol and hematin. A linear calibration graph was obtained over the range 2.0x10^?6-8.5 x 10^?5 mol L^?1. The method was applied to determining glucose in blood serum, urine and fruit juices.