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Bioelectrocatalytic...
Bioelectrocatalytic detection of theophylline at theophylline oxidase electrodes
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Ferapontova, Elena E. (author)
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Shipovskov, Stepan (author)
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- Gorton, Lo (author)
- Lund University,Lunds universitet,Centrum för analys och syntes,Kemiska institutionen,Institutioner vid LTH,Lunds Tekniska Högskola,Centre for Analysis and Synthesis,Department of Chemistry,Departments at LTH,Faculty of Engineering, LTH
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(creator_code:org_t)
- Elsevier BV, 2007
- 2007
- English.
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In: Biosensors & Bioelectronics. - : Elsevier BV. - 1873-4235 .- 0956-5663. ; 22:11, s. 2508-2515
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http://dx.doi.org/10...
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Abstract
Subject headings
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- Bioelectrocatalytic oxidation of theophylline was studied at gold and graphite electrodes modified with microbial theophylline oxidase (ThOx), a multi-cofactor redox enzyme capable of selective oxidation of theophylline. Gold electrodes were additionally modified with self-assembled monolayers (SAMs) of (-OH)- and (-NH2)-terminated alkanethiols of different chain lengths, to achieve compatibility between ThOx and the electrode surface. On graphite, ThOx was either physically co-adsorbed with a surfactant didodecyldimethylammonium bromide (DDAB), or entrapped within an Os-redox-polymer film. At all electrodes, ThOx was bioelectrocatalytically active; direct electrochemistry of ThOx in the absence of theophylline was followed only at the SAM-modified gold electrodes. Direct electrochemistry of ThOx correlated with redox transformations of the heme domain of ThOx, with a E-o/ of - 110 +/- 2 mV versus Ag vertical bar AgCl, at pH 7. Bioelectrocatalytic oxidation of theophylline was optimal at mixed (-OH)/(-NH2)-terminated SAMs; co-adsorption of ThOx with DDAB improved the bioelectrocatalytic performance of the ThOx-electrode. In both cases, the response to theophylline was within the mM range. Alternatively, a reagentless ThOx-electrode based on ThOx cross-linked within the Os-redox-polymer matrix demonstrated a linear response to theophylline within the physiologically important 0.02-0.6 mM (3.6-72 mg I-1) concentration range with a sensitivity of 52.1 +/- 7.8 mA cm(-2) m(-1). (c) 2006 Elsevier B.V. All rights reserved.
Subject headings
- NATURVETENSKAP -- Kemi -- Analytisk kemi (hsv//swe)
- NATURAL SCIENCES -- Chemical Sciences -- Analytical Chemistry (hsv//eng)
Keyword
- graphite
- gold
- alkanethiols
- theophylline oxidase
- bioelectrocatalysis
- osmium-complex redox polymer
Publication and Content Type
- art (subject category)
- ref (subject category)
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