Abstract
This report describes technical improvements to the manufacture of a carbon fibre electrode for the stable and sensitive detection of H2O2 (detection limit at 0.5 mu M). This electrode was also modified through the co-immobilisation of acetylcholinesterase (AChE) and/or choline oxidase (ChOx) in a bovine serum albumin (BSA) membrane for the development of a sensor for in vivo measurements of acetylcholine and choline. Amperometric measurements were performed using a conventional three-electrode system forming part of a flow-injection set-up at an applied potential of 800-1100 mV relative to an Ag/AgCl reference electrode. The optimised biosensor obtained was reproducible and stable, and exhibited a detection limit of 1 mu M for both acetylcholine and choline. However, due to the high operating potential used, the biosensor was prone to substantial interference from other electroactive compounds, such as ascorbic acid. Therefore, in a further step, a mediated electron transfer approach was used that incorporated horseradish peroxidase into an osmium-based redox hydrogel layered into the active surface of the electrode. Afterwards, a Nafion layer and a coating containing AChE and/or ChOx co-immobilised in a BSA membrane were successively deposited. This procedure further increased the selectivity of the biosensor, when operated in the same flow-injection system but at an applied potential of -50 mV relative to an Ag/AgCl reference electrode. The sensor exhibited good selectivity and a high sensitivity over a concentration range (0.3-100 mu M) suitable for the measurement of choline and acetylcholine in vivo. (c) 2004 Elsevier B.V. All rights reserved.
Original language | English |
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Pages (from-to) | 87-94 |
Journal | Biosensors & Bioelectronics |
Volume | 21 |
Issue number | 1 |
DOIs | |
Publication status | Published - 2005 |
Subject classification (UKÄ)
- Industrial Biotechnology
Free keywords
- selectivity
- sensitivity
- choline
- amperometric microbiosensor
- carbon fibre electrode
- mediated electron
- acetylcholine
- transfer