Amperometric tetrathiafulvalene-mediated lactate electrode using lactate oxidase absorbed on carbon foil

The features of a new sensor for determining l-lactate are reported. The enzyme lactate oxidase and the mediator, tetrathiafulvalene (TTF), are absorbed on carbon foil disks previously bonded onto the ends of glass tubes. Linear calibration graphs were obtained in the range 10^?4?10^?3 M with physiological phosphate buffer (pH 7.35) and at 30°C with a response time of a few seconds. Calibration graphs in the range 10^?3?10^?2 M were also obtained and the difference in response times between these two ranges were investigated. The results are promising for assembling disposable lactate sensors for in vitro or for in or ex vivo measurements.     

Amperometric determination of serum lactate dehydrogenase activity using an ADP-modified graphite electrode

Graphite electrodes modified with a drop-coated layer of polyethyleneimine (PEI) and adenosine diphosphate (ADP) displayed an electrocatalytic response to NADH after the adenine moiety of ADP was electrochemically oxidised. NADH can be detected amperometrically in alkaline solution (pH 9.0) at low applied potentials (+50 mV (Ag/AgCl)). Using a stationary electrode arrangement, linear response for NADH concentrations between 1.0×10⁻⁸ and 1.0×10⁻⁴ M was found, with a response time of 12 s and a detection limit of 8×10⁻⁹ M. The electrode was applied to the amperometric monitoring of the reaction between lactate and NAD⁺ catalysed by lactate dehydrogenase (LDH). A flow injection-amperometric method for the determination of LDH activity in human serum was developed. The method allows a fast and accurate discrimination between pathological and normal LDH activity levels, with a sampling rate of 40 h⁻¹. Quantitative results for a random set of human serum samples were found to be in good agreement with the standard spectrophotometric method.     

Amperometric lactate nanobiosensor based on reduced graphene oxide,carbon nanotube and gold nanoparticle nanocomposite

Microchimica Acta - Copper nanoclusters (CuNCs) are an attractive alternative to other metal nanoclusters. The synthesis of CuNCs is highly efficient and fast, with low-cost and without any...     

Amperometric lactate biosensors and their application in (sports) medicine, for life quality and wellbeing

The article reviews the use of electrochemical biosensors for detecting lactate, a key metabolite of the anaerobic glycolytic pathway. This compound plays an important role in (sports) medicine, in the nutritional sector, in food quality control and touches environmental concerns. Amperometric biosensors offer a sensitive and selective means to monitor organic analytes like lactate. A detailed study on different aspects of amperometric lactate biosensor preparation is described: the main configuration aspects are compiled regarding electrode materials, biorecognition elements, immobilization methods, mediators and cofactors as well as fields of application. Comparative studies are conducted correlating different configuration aspects and performance of the resulting biosensors. This review contains 214 references from the years 1974 to 2007. Correspondence: Beate Strehlitz, UFZ, Helmholtz Centre for Environmental Research – UFZ, Environmental and Biotechnology Centre (UBZ), Permoserstrasse 15, D-04318 Leipzig, Germany     

Amperometric enzyme electrodes of glucose and lactate based on poly(diallyldimethylammonium)-alginate-metal ion-enzyme biocomposites

Sodium alginate (AlgNa) and poly(diallyldimethylammonium chloride) (PDDA) were mixed to obtain an interpenetrating polymer composite via electrostatic interaction and then cast on an Au electrode surface, followed by incorporation of metal ions (e.g. Fe³⁺ or Ca²⁺, to form AlgFe or AlgCa hydrogel) and glucose oxidase (GOx) (or lactate oxidase (LOx)), to prepare amperometric enzyme electrodes. The interactions of PDDA, Alg, and Fe³⁺ are studied by visual inspection as well as microscopic and electrochemical methods. Under optimized conditions, the PDDA-AlgFe-enzyme/Au and PDDA-AlgCa-enzyme/Au electrodes can give good analytical performance (e.g. nM-scale limit of detection of glucose or lactate, and sensitivities > 50 μA cm⁻² mM⁻¹) in the first-generation biosensing mode, which are better than the reported analogs using typical polysaccharide biopolymers as enzyme-immobilization matrices. The enzyme electrodes also worked well in the second-generation biosensing mode in the coexistence of p-benzoquione or ferrocene monocarboxylic acid artificial mediator. Biofuel cells (BFCs) with the enzyme electrodes as the bioanodes and glucose (or lactate) as the biofuel were also fabricated with satisfactory results. The proposed protocols for preparation of high performance Alg-based biocomposites may find wide applications in bioanalysis.     

Amperometric monitoring of bacteria-induced milk acidity using a platinum disc microelectrode.

The acidity induced by the action of bacteria in milk samples was monitored amperometrically by using a platinum microelectrode. The measurements were performed directly on commercial packs of milk, stored at 32 degrees C, and were continued for 9-10 d after inoculation. The data were compared with those obtained by measuring the pH of the samples and the results are discussed on the basis of the metabolism of each bacterial species. The effects of the following bacteria were examined: Staphylococcus aureus, Bacillus cereus, Streptococcus faecalis, Bacillus subtilis, Aeromonas, and Corynebacterium.     

Amperometric lactate biosensor for flow injection analysis based on a screen-printed carbon electrode containing Meldola's Blue-Reinecke salt, coated with lactate dehydrogenase and NAD

A biosensor for the measurement of lactate in serum has been developed, which is based on a screen-printed carbon electrode, modified with Meldola's Blue-Reinecke Salt (MBRS-SPCE), coated with the enzyme lactate dehydrogenase NAD⁺ dependent (from Porcine heart), and NAD⁺. A cellulose acetate layer was deposited on the top of the device to act as a permselective membrane. The biosensor was incorporated into a commercially available, thin-layer, amperometric flow cell operated at a potential of only +0.05 V vs. Ag/AgCl. The mobile phase consisted of 0.2 M phosphate buffer pH 10 containing 0.1 M potassium chloride solution; a flow rate of 0.8 ml min⁻¹ was used throughout the investigation. The biosensor response was linear over the range 0.55-10 mM lactate; the former represents the detection limit. The precision of the system was determined by carrying out 10 repeat injections of 10 mM l(+)lactic acid standard; the calculated coefficient of variation was 4.28%. It was demonstrated that this biosensor system could be applied to the direct measurement of lactate in serum without pre-treatment; therefore, this would allow high throughput-analysis, at low cost, for this clinically important analyte.     

Impact of high pyruvate concentration on kinetics of rabbit muscle lactate dehydrogenase

In order to evaluate the effectiveness of l-lactate dehydrogenase (LDH) from rabbit muscle as a regenerative catalyst of the biologically important cofactor nicotinamide adenine dinucleotide (NAD), the kinetics over broad concentrations were studied to develop a suitable kinetic rate expression. Despite robust literature describing the intricate complexations, the mammalian rabbit muscle LDH lacks a quantitative kinetic rate expression accounting for simultaneous inhibition parameters, specifically at high pyruvate concentrations. Product inhibition by l-lactate was observed to reduce activity at concentrations greater than 25 mM, while expected substrate inhibition by pyruvate was significant above 4.3 mM concentration. The combined effect of ternary and binary complexes of pyruvate and the coenzymes led to experimental rates as little as a third of expected activity. The convenience of the statistical software package JMP allowed for effective determination of experimental kinetic constants and simplification to a suitable rate expression:

Protective effect of ischemic postconditioning against ischemia reperfusion-induced myocardium oxidative injury in IR rats

Brief episodes of myocardial ischemia-reperfusion (IR) employed during reperfusion after a prolonged ischemic insult may attenuate the total ischemia-reperfusion injury. This phenomenon has been termed ischemic postconditioning. In the present study, we studied the possible effect of ischemic postconditioning on an ischemic reperfusion (IR)-induced myocardium oxidative injury in rat model. Results showed that ischemic postconditioning could improve arrhythmia cordis, reduce myocardium infarction and serum creatin kinase (CK), lactate dehydrogenase (LDH) and aspartate transaminase (AST) activities in IR rats. In addition, ischemic postconditioning could still decrease myocardium malondialdehyde (MDA) level, and increased myocardium Na+-K+-ATPase, Ca2+-Mg2+-ATPase, superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GSH-Px) and glutathione reductase (GR) activities. It can be concluded that ischemic postconditioning possesses strong protective effects against ischemia reperfusion-induced myocardium oxidative injury in IR rats.     

Amperometric monitoring of redox activity in intact,permeabilised and lyophilised cells of the yeast Hansenula polymorpha

An effect of permeabilisation and lyophilisation of the yeast cells Hansenula polymorpha on their electrochemical behaviour in the presence of mediators, substrates (formaldehyde, glucose, methanol, ethanol), and cofactors (NAD⁺, NADP⁺, NADH, NADPH, glutathione) has been studied. Two amperometric techniques differing in the cell immobilisation methods were applied. The cells of a wild strain (356) and mutant strains (C-105 and KCA 33) of the yeast, grown in the presence of glucose or methanol, were used in the experiments. The intact cells revealed the highest reduction rates of mediators, 2,6-dichlorphenolindophenol (DCIP) and 2,4-benzoquinone (BQ), as measured by amperometry. The addition of formaldehyde significantly enhanced the response, if the cells were grown in the presence of glucose. The permeabilised cells showed the lowest current level in the presence of DCIP and BQ and no response to the addition of formaldehyde and NAD⁺. However, the addition of NADH gave significant current surge. All these phenomena imply that the permeabilised cells lost cofactors and the activity of dehydrogenases producing NADH, but they remained the activity of NADH-ubiquinone oxidoreductase and of some components of the electron transport chain. The electrochemical behaviour of the lyophilised cells shows they are heterogeneous. The partial degradation of the outer membrane of the cells after their lyophilisation was electrochemically confirmed.     

Abortive complexes as a cause of substrate inhibition of rabbit muscle lactate dehydrogenase

Rabbit skeletal muscle lactate dehydrogenase follows the Michaelis—Menten kinetics and is adapted to an ordered, sequential type mechanism. The determination of the initial reaction rates allows am empirical rate equation, allowing the substrate and reaction product inhibition of the lactate dehydrogenase to be deduced.An overall reaction scheme, including all the possible complex formations which may be responsible for the inhibition, is formulated. The theoretical rate equation is determined from this scheme by the method of King and Altman and it is compared with the experimental results. The inhibition brought about by the reaction products and by excess substrate is justified by the existence of the E—pyruvate and E—NAD—NAD abortive complexes, which have not been postulated previously for rabbit muscle lactate dehydrogenase. The proposed rate equation gives a general interpretation of the kinetic behavior of rabbit skeletal muscle lactate dehydrogenase, some of its aspects still being under discussion.     

In-situ monitoring of cell-secreted lactate by electrochemiluminescence sensing under biomimetic microfluidic confinement

Cell migration proceeds in 3D matrices in vivo, which can naturally switch to distinct phenotypes for better invasion in confined microenvironments. The studies of important metabolites under confinement are extremely meaningful for comprehensive insights into cancer metastasis. The integration of cell confinement device and analytical techniques is a key point for in-situ analysis of significant metabolites in vitro.Herein, an electrochemiluminescence(ECL) sensing platform was designed for in-s...     

Amperometric determination of lactate dehydrogenase based on a carbon fiber microcylinder electrode modified covalently with Toluidine Blue O by acylation

A method has been developed for the modification of a carbon fiber microcylinder electrode with acylation. The stability and surface coverage of the Toluidine Blue O-modified microelectrode were studied by cyclic voltammetry. The modified electrode showed significant activity for the electrocatalytic oxidation of NADH in pH 6.8-7.8 solution. The catalytic current increased linearly with increasing concentration of NADH from 4.0 x 10(-5) to 1.5 x 10(-3) M. A simple amperometric determination based on electrochemical detection of NADH produced from the enzymatic reaction of lactate with NAD(+) under the catalysic effect of lactate dehydrogenase (LDH) is reported. The experimental factors which had primary influence on the analytical performance were studied. The sensor had a linear response over a range of LDH concentrations from 5.0 U l(-1) to 200 U l(-1) at -0.2 V vs. SCE under optimum conditions. A satisfactory result was obtained for the determination of LDH in clinical blood samples.     

Amperometric titration of copper in brass

A direct amperometric titration of copper is described; o-(p-tolylsulfonamido) aniline serves as titrant. The optimum conditions are discussed and the method is applied to the analysis of copper in brass alloys.

t001. IV. Analysis of various samples in which copper was determined (Values given as percentages)

     

17.

Amperometric titration of molybdenum     

G.H. Aylward 《Analytica chimica acta》1956

A method for the amperometric titration of molybdenum(Vl) with lead nitrate solution is described. The precipitation is carried out at room temperature from an acid sodium acetatepotassium chloride supporting electrolyte. The diffusion currents are recorded at a potential of —0.8 V vs. S.C.E. where both the lead and molybdenum give reduction waves. While the reduction of molybdenum in acetic acid buffer produces no well defined plateau, it gives accurate and reproducible results amperometrically. The analytical precision is about 0.4%.     

18.

Amperometric estimation of palladium     

A.K. Majumdar  M.M. Chakrabartty 《Analytica chimica acta》1959

In sodium acetate acid buffer the diffusion currents of palladium and of the reagents bismuthiol 1, bissmuthiol II, 2-mereaptobenzothiazole and 2-mereaptobenzimidazole remain Constant respectively at potentials (vs S.C.E.) of —0.3 to —0.8 V, 0.0 to —0.3 V, 0.0 to —0.8 V, —0.4 to —0.6 V and —0.2 to —0.7 V respectively. Bismuthiol 1, at an applied potential of —0.3V, is effective for the estimation of 1.2 to 2.5 mg of palladium, whereas bismuthiol II and 2-mercaptobenzimidazole give highly satisfactory results with 1.2 to 6.0 mg of palladium at a potential of —0.5 V. 2-Mercaptobenzothiazole at the latter potential gives an error of about 5% when the concentration of palladium is about 6.0 mg.     

19.

Freshwater molluscs as accumulation indicators for monitoring heavy metal pollution     

Lilla Zadory 《Fresenius' Journal of Analytical Chemistry》1984,317(3-4):375-379

Summary For monitoring heavy metal pollution of streams in urban and industrial areas residue analyses were undertaken in different aquatic invertebrates with special regard to the freshwater molluscs Bithynia tentaculata, Physa acuta, Radix peregra and Dreissena polymorpha to define the heavy metal residues in shell and soft body parts in natural populations.To control the distribution and dynamics of the heavy metals, the accumulation and elimination behaviour is determined after experimental contamination tests with cadmium, lead and zinc and their complexes for synergisms on standardized populations under laboratory conditions.Due to a strong accumulation of these organisms they appear to be well suited for monitoring programs. Experimental studies show, that zinc and lead absorbed with the food accumulate in the haemolymph, the food muscle and the protein gland. The different rates of accumulation depend however among others on the different physiological variables as well as on population specific strategies. Furthermore, different mechanisms result in a rivalry among the heavy metals for uptake.

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Süßwasser-Mollusken als Indicatoren für die Schwermetallbelastung

Zusammenfassung Zur Aufklärung der Schwermetallbelastung der Fließgewässer wurden Rückstandsanalysen in verschiedenen limnischen Invertebraten durchgeführt, mit besonderer Berücksichtigung der Mollusken Bithynia tentaculata, Physa acuta, Radix peregra und Dreissena polymorpha. Die Verteilung und Dynamik der Substanzen wurde in Kontaminationstests mit Cadmium, Blei und Zink sowie mit verschiedenen Komplexen unter standardisierten Laborbedingungen überprüft. Die Ergebnisse lassen Mollusken als geeignete Organismen für Monitoring-Programme erscheinen, wobei verschiedene populationsspezifische Strategien zu berücksichtigen sind.

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Dedicated to Prof. Dr. W. Fresenius on the occasion of his 70th birthday     

20.

Amperometric enzyme electrodes in analytical chemistry     

J. J. Kulys 《Fresenius' Journal of Analytical Chemistry》1989,335(1):86-91

Summary An overview is given of works on the construction and application of amperometric enzyme electrodes for the determination of metabolites in biological solutions. The following electrodes are dealt with: monoenzyme and polyenzyme electrodes involving amperometric detection of hydrogen peroxide, bienzyme electrodes with oxidase-peroxidase, electrodes based on organic metals and chemically modified electrodes, dehydrogenase electrodes, amperometric hydrolase electrodes and highly sensitive electrodes involving chemical amplification. Biocatalytic stripping and macrokinetic behaviour of the electrodes are discussed.

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Amperometrische Enzymelektroden in der analytischen Chemie

     

Constituents	Thorn Smith # 30	Thorn Smith # 54	NBS # 37E	NBS # 63C
Cu present	59.30	84.04	69.61	80.48
Zn	37.81	1.452	27.85	0.093
Pb	0.1	8.590	1.00	9.35
Sn	Trace	5.737	1.00	9.03
Sb				0.52
Ni	Trace		0.53	0.32
P				0.145
S				0.060
As				0.023
Fe	1.22		0.004	0.0013
Al	1.15
Mn	0.35
Cu found	59.09	83.64	69.68a	80.54a	aAverage of 3 determinations.

Amperometric titration of molybdenum

A method for the amperometric titration of molybdenum(Vl) with lead nitrate solution is described. The precipitation is carried out at room temperature from an acid sodium acetatepotassium chloride supporting electrolyte. The diffusion currents are recorded at a potential of —0.8 V vs. S.C.E. where both the lead and molybdenum give reduction waves. While the reduction of molybdenum in acetic acid buffer produces no well defined plateau, it gives accurate and reproducible results amperometrically. The analytical precision is about 0.4%.     

Amperometric estimation of palladium

In sodium acetate acid buffer the diffusion currents of palladium and of the reagents bismuthiol 1, bissmuthiol II, 2-mereaptobenzothiazole and 2-mereaptobenzimidazole remain Constant respectively at potentials (vs S.C.E.) of —0.3 to —0.8 V, 0.0 to —0.3 V, 0.0 to —0.8 V, —0.4 to —0.6 V and —0.2 to —0.7 V respectively. Bismuthiol 1, at an applied potential of —0.3V, is effective for the estimation of 1.2 to 2.5 mg of palladium, whereas bismuthiol II and 2-mercaptobenzimidazole give highly satisfactory results with 1.2 to 6.0 mg of palladium at a potential of —0.5 V. 2-Mercaptobenzothiazole at the latter potential gives an error of about 5% when the concentration of palladium is about 6.0 mg.     

Freshwater molluscs as accumulation indicators for monitoring heavy metal pollution

Summary For monitoring heavy metal pollution of streams in urban and industrial areas residue analyses were undertaken in different aquatic invertebrates with special regard to the freshwater molluscs Bithynia tentaculata, Physa acuta, Radix peregra and Dreissena polymorpha to define the heavy metal residues in shell and soft body parts in natural populations.To control the distribution and dynamics of the heavy metals, the accumulation and elimination behaviour is determined after experimental contamination tests with cadmium, lead and zinc and their complexes for synergisms on standardized populations under laboratory conditions.Due to a strong accumulation of these organisms they appear to be well suited for monitoring programs. Experimental studies show, that zinc and lead absorbed with the food accumulate in the haemolymph, the food muscle and the protein gland. The different rates of accumulation depend however among others on the different physiological variables as well as on population specific strategies. Furthermore, different mechanisms result in a rivalry among the heavy metals for uptake.

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Süßwasser-Mollusken als Indicatoren für die Schwermetallbelastung

Zusammenfassung Zur Aufklärung der Schwermetallbelastung der Fließgewässer wurden Rückstandsanalysen in verschiedenen limnischen Invertebraten durchgeführt, mit besonderer Berücksichtigung der Mollusken Bithynia tentaculata, Physa acuta, Radix peregra und Dreissena polymorpha. Die Verteilung und Dynamik der Substanzen wurde in Kontaminationstests mit Cadmium, Blei und Zink sowie mit verschiedenen Komplexen unter standardisierten Laborbedingungen überprüft. Die Ergebnisse lassen Mollusken als geeignete Organismen für Monitoring-Programme erscheinen, wobei verschiedene populationsspezifische Strategien zu berücksichtigen sind.

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Dedicated to Prof. Dr. W. Fresenius on the occasion of his 70th birthday     

Amperometric enzyme electrodes in analytical chemistry

Summary An overview is given of works on the construction and application of amperometric enzyme electrodes for the determination of metabolites in biological solutions. The following electrodes are dealt with: monoenzyme and polyenzyme electrodes involving amperometric detection of hydrogen peroxide, bienzyme electrodes with oxidase-peroxidase, electrodes based on organic metals and chemically modified electrodes, dehydrogenase electrodes, amperometric hydrolase electrodes and highly sensitive electrodes involving chemical amplification. Biocatalytic stripping and macrokinetic behaviour of the electrodes are discussed.

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Amperometrische Enzymelektroden in der analytischen Chemie