Homogeneous ferrocene-mediated amperometric immunoassay

K, Di Gleria; Ha, Hill; Cj, McNeil; Green, Melissa

doi:10.1021/ac00297a050

Cited by 132 publications

(34 citation statements)

References 10 publications

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“…Many such redox mediators have been used successfully, including metallocenes, quinones, ferrocyanide and tetrathiafulvalene (Di Gleria et al, 1986;Wang, 1993). The advantages of such devices are that the electrode may be operated at lower applied anodic potentials, and since molecular oxygen is not the final electron acceptor, these sensors might be expected to be relatively independent of changes in pO 2 .…”

Section: Introductionmentioning

confidence: 99%

Characterization in vitro and in vivo of the oxygen dependence of an enzyme/polymer biosensor for monitoring brain glucose

Dixon

Lowry

O’Neill

2002

Journal of Neuroscience Methods

108

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The oxygen dependence of a first generation amperometric biosensor was investigated in vitro and in vivo by monitoring its glucose response as a function of solution pO 2 . The biosensor was a glucose oxidase (GOx) modified poly(o -phenylenediamine) coated Pt cylinder electrode (Pt/PPD/GOx) that has been designed for neurochemical analysis in vivo. Two types of oxygen probes were used: a self-calibrating commercial macroelectrode in vitro; and a carbon paste microelectrode in vivo. Calibrations in vitro showed that oxygen interference in the operation of Pt/PPD/GOx electrodes was minimal for concentrations of glucose ( Â/0.5 mM) and oxygen ( Â/50 mM) found in brain ECF. This observation was confirmed by simultaneous monitoring in vivo of brain glucose and oxygen in the awake rat. However, at levels of glucose normally found in peripheral tissues ( Â/5 mM), the oxygen dependence was severe. We conclude that the oxygen sensitivity of Pt/PPD/GOx biosensors does not preclude their reliable use in media containing low glucose levels, such as brain ECF. #

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Section: Introductionmentioning

confidence: 99%

Characterization in vitro and in vivo of the oxygen dependence of an enzyme/polymer biosensor for monitoring brain glucose

Dixon

Lowry

O’Neill

2002

Journal of Neuroscience Methods

108

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“…The catalytic current produced in the system is therefore dependent upon the concentration of antigen in solution. The principle has been demonstrated in assays for lidocaine [78], theophylline [66] and thyroxine "791.…”

Section: Analytical Systems Based On Mediated Electron Transfermentioning

confidence: 99%

Direct and indirect electron transfer between electrodes and redox proteins

Frew¹,

Hill

1988

European Journal of Biochemistry

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298

118

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The direct electrochemistry of redox proteins has been achieved at a variety of electrodes, including modified gold, pyrolytic graphite and metal oxides. Careful design of electrode surfaces and electrolyte conditions are required for the attainment of rapid and reversible protein-electrode interaction. The electron transfer reactions of more complex systems, such as redox enzymes, are now being examined. The 'well-behaved' electrochemistry of redox proteins can be usefully exploited by coupling the electrode reaction to enzymes for which the redox proteins act as cofactors. In systems where direct electron transfer is very slow, small electron carriers, or mediators, may be employed to enhance the rate of electron exchange with the electrode. The organometallic compound ferrocene and its derivatives have proved particularly effective in this role. A new generation of electrochemical biosensors employs ferrocene derivatives as mediators.Many of the fundamental processes in Nature rely upon the redox processes of constituent biomolecules. Cell respiration involves the stepwise oxidation of organic substrates via a cascade of redox reactions. In photosynthetic organisms, chains of electron carriers, for example, flavoproteins, ironsulphur proteins and cytochromes, participate in light-induced photosynthetic electron transport. The intrinsic mechanisms of electron transfer reactions, and the detailed role of the protein in aiding the electron transfer between redox centres, have become foci for extensive physical and biochemical investigations [l].Electrochemistry provides a powerful tool for examining electron transfer properties. The molecules of particular interest are redox-active proteins and enzymes. Although there have been many investigations of the electrochemical behaviour of the isolated and 'free' prosthetic groups [2, 31, the properties of the latter in an intact protein are so perturbed that to gain an understanding of their biological role, it is essential to have information on the behaviour of the proteins themselves.Only relatively recently has the feasibility of studying the electron transfer reactions of redox proteins at an electrode surface been viewed with any real optimism. Indeed, for many years it was thought that reversible, direct electron transfer (i. e. without mediation by small electron carriers) between electrodes and redox proteins was not possible. Several reasons were given: the slow rates of diffusion of these species were presumed to lead to greatly diminished faradaic currents; the 'buried' nature of the redox groups would make interaction with an electrode prohibitive for all but a few orientations of the protein at the electrode surface and proteins appeared to denature at the electrode-electrolyte interface. In fact, the early studies of protein electrochemistry were unlikely to succeed simply due to the type of electrodes used [4-61. Mercury was the favoured electrode material and, in such systems, adsorption phenomena play a predominant role with the possibility of confor...

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“…Di Gleria et al (1986) described a mediated electrochemical biosensor using ferrocene instead of dioxygen to alleviate electroactive interfering species such as uric and ascorbic acids. This elegant procedure formed the basis for successful commercialization of a glucose pen by Medisense.…”

Section: Introductionmentioning

confidence: 99%