Biochemical cell for the determination of lactate

Kulys, Juozas; Švirmickas, Gintautas Juozas

doi:10.1016/s0003-2670(01)84226-4

Cited by 14 publications

(3 citation statements)

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“…6 Alternatively, artif icial electron shuttles, commonly ref erred to as " mediators" , can be introduced into the system and replace the natural co-substrate in the reaction. [7][8][9] The process of indirect electron transf er utilising artif icial electron shuttles is termed mediated electron transfer (MET).…”

Section: Acknowledgmentsmentioning

confidence: 99%

“…Despite several attempts to use quiones, azines and metal complexes 7,8 as mediators in the 1970s, the wider application of mediated systems did not begin until the discovery of the possibility to use the ferricinium ion (oxidised ferrocene) as a mediator for GOx in 1984. 67 Ferrocene and its derivatives, ferri/ferrocyanide complexes of transition metals such as osmium and ruthenium as well as redox organic dyes (mainly azines) are widely used redox mediators for oxidases.…”

Section: Commonly Used Mediated Systemsmentioning

confidence: 99%

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Facilitating electron transfer in bioelectrocatalytic systems

Sekretaryova¹

2016

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During the course of the research underlying this thesis, Alina Sekretaryova was enrolled in Forum Scientium, a multidisciplinary doctoral programme at Linköping University, Sweden Alina Sekretaryova, 2016, unless otherwise noted. Cover design by Alina Sekretaryova Linköping studies in science and technology Dissertation No. 1738 Printed in Sweden by LiU-Tryck, Linköping, Sweden, 2016 iii ABSTRACT Bioelectrocatalytic systems are based on biological entities, such as enzymes, whole cells, parts of cells or tissues, which catalyse electrochemical processes that involve the interaction between chemical change and electrical energy. In all cases, enzymes, isolated or residing inside cells or part of cells, implement biocatalysis. Electron transfer phenomena, within the protein molecules and between biological redox systems and electronics, enable the development of various bioelectrocatalytic systems, which can be used both for fundamental investigations of enzymatic biological processes by electrochemical methods and for applied purposes, such as power generation, bioremediation, chemical synthesis and biosensing.Electrical communication between the biocatalysts redox centre and an electrode is essential for the functioning of the system. This can be established using two main mechanisms: indirect electron transfer and direct electron transfer. The efficiency of the electron transfer influences important parameters such as the turnover rate of the biocatalyst, the generated current density and partially the stability of the system. These in turn determine the response time, sensitivity, detection limit and operational stability of biosensors or the power densities and current output of biofuel cells, and hence they should be carefully considered when designing bioelectrocatalytic systems.This thesis focuses on approaches that facilitate electron transfer in bioelectrocatalytic systems based on mediated and direct electron transfer mechanisms. Both fundamental aspects of electron transfer in bioelectrocatalytic systems and applications of such systems for biosensing and power generation are considered. First, a new hydrophobic mediator for oxidases, unsubstituted phenothiazine, and its improved electron transfer properties in comparison with commonly used mediators are discussed. Application of the mediator in electrochemical biosensors is demonstrated by glucose, lactate and cholesterol sensing. Utilisation of mediated biocatalytic cholesterol oxidation as the anodic reaction for the construction of a biofuel cell, acting as a power supply and an analytical device at the same time, is investigated as a "self-powered" biosensor. In addition, the enhancement of mediated bioelectrocatalysis by the employment of microelectrodes as a transducer is examined. The effect of surface roughness on the current response of the microelectrodes under conditions of convergent diffusion is considered. The applicability of the laccase-based system for total phenol analysis of weakly supported water is demonstrated. Finally, a...

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Section: Acknowledgmentsmentioning

confidence: 99%

Section: Commonly Used Mediated Systemsmentioning

confidence: 99%

Facilitating electron transfer in bioelectrocatalytic systems

Sekretaryova¹

2016

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“…Despite several attempts to use quiones, azines and metal complexes 66,67 as mediators in the 1970s, wide application of mediated biosensors started from the discovery of the possibility to use the ferricinium ion (oxidized ferrocene) as a mediator for GOx in 1984. 68 …”

Section: Mediated Biosensorsmentioning

confidence: 99%

Novel reagentless electrodes for biosensing

Sekretaryova¹

2014

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Analytical chemical information is needed in all areas of human activity including health care, pharmacology, food control and environmental chemistry. Today one of the main challenges in analytical chemistry is the development of methods to perform accurate and sensitive rapid analysis and monitoring of analytes in 'real' samples. Electrochemical biosensors are ideally suited for these applications.Despite the wide application of electrochemical biosensors, they have some limitations. Thus, there is a demand on improvement of biosensor performance together with a necessity of simplification required for their mass production. In this thesis the work is focused on the development of electrochemical sensors with improved performance applicable for mass production, e.g. by screen printing.Biosensors using immobilized oxidases as the bio-recognition element are among the most widely used electrochemical devices. Electrical communication between redox enzymes and electrodes can be established by using natural or synthetic electron carriers as mediators. However, sensors based on soluble electronshuttling redox couples have low operational stability due to the leakage of water-soluble mediators to the solution. We have found a new hydrophobic mediator for oxidases -unsubstituted phenothiazine. Phenothiazine and glucose oxidase, lactate oxidase or cholesterol oxidase were successfully co-immobilized in a sol-gel membrane on a screen-printed electrode to construct glucose, lactate and cholesterol biosensors, respectively. All elaborated biosensors with phenothiazine as a mediator exhibited long-term operational stability. A kinetic study of the mediator has shown that phenothiazine is able to function as an efficient mediator in oxidase-based biosensors.To improve sensitivity of the biosensors and simplify their production we have developed a simple approach for production of graphite microelectrode arrays. Arrays of microband electrodes were produced by screen printing followed by scissor cutting, which enabled the realization of microband arrays at the cut edge. The analytical performance of the system is illustrated by the detection of ascorbic acid through direct oxidation and by detection of glucose using a phenothiazine mediated glucose biosensor. Both systems showed enhanced sensitivity due to improved mass transport. Moreover, the developed approach can be adapted to automated electrode recovery.Finally, two enzyme-based electrocatalytic systems with oxidation and reduction responses, respectively, have been combined into a fuel cell generating a current as an analytical output (a so-called self-powered biosensor). This was possible as a result of the development of the phenothiazine mediated enzyme electrodes, Abstract which enabled the construction of a cholesterol biosensor with self-powered configuration. The biosensor generates a current when analyte (cholesterol) is added to the cell. The biosensor has been applied for whole plasma analysis.All developed concepts in the thesis are compatible with ...

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