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Bioelectrocatalytic detection of theophylline at theophylline oxidase electrodes

Ferapontova, Elena E.; Shipovskov, Stepan and Gorton, Lo LU (2007) In Biosensors & Bioelectronics 22(11). p.2508-2515
Abstract
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... (More)
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. (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
graphite, gold, alkanethiols, theophylline oxidase, bioelectrocatalysis, osmium-complex redox polymer
in
Biosensors & Bioelectronics
volume
22
issue
11
pages
2508 - 2515
publisher
Elsevier
external identifiers
  • wos:000246382500017
  • scopus:33947596231
ISSN
1873-4235
DOI
10.1016/j.bios.2006.09.034
language
English
LU publication?
yes
id
3093a750-285e-4254-8f5e-0ec7120df3a9 (old id 660586)
date added to LUP
2007-12-11 14:15:42
date last changed
2017-11-12 03:51:15
@article{3093a750-285e-4254-8f5e-0ec7120df3a9,
  abstract     = {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.},
  author       = {Ferapontova, Elena E. and Shipovskov, Stepan and Gorton, Lo},
  issn         = {1873-4235},
  keyword      = {graphite,gold,alkanethiols,theophylline oxidase,bioelectrocatalysis,osmium-complex redox polymer},
  language     = {eng},
  number       = {11},
  pages        = {2508--2515},
  publisher    = {Elsevier},
  series       = {Biosensors & Bioelectronics},
  title        = {Bioelectrocatalytic detection of theophylline at theophylline oxidase electrodes},
  url          = {http://dx.doi.org/10.1016/j.bios.2006.09.034},
  volume       = {22},
  year         = {2007},
}