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Sensors 2012, 12(3), 3037-3048; doi:10.3390/s120303037
Article

A Reusable Impedimetric Aptasensor for Detection of Thrombin Employing a Graphite-Epoxy Composite Electrode

,
 and *
Sensors and Biosensors Group, Department of Chemistry, Universitat Autònoma de Barcelona, Bellaterra 08193, Spain
* Author to whom correspondence should be addressed.
Received: 13 January 2012 / Revised: 15 February 2012 / Accepted: 23 February 2012 / Published: 6 March 2012
(This article belongs to the Special Issue Sensors and Biosensors Using Label Free Chemistries)
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Abstract

Here, we report the application of a label-free electrochemical aptasensor based on a graphite-epoxy composite electrode for the detection of thrombin; in this work, aptamers were immobilized onto the electrodes surface using wet physical adsorption. The detection principle is based on the changes of the interfacial properties of the electrode; these were probed in the presence of the reversible redox couple [Fe(CN)6]3−/[Fe(CN)6]4− using impedance measurements. The electrode surface was partially blocked due to formation of aptamer-thrombin complex, resulting in an increase of the interfacial electron-transfer resistance detected by Electrochemical Impedance Spectroscopy (EIS). The aptasensor showed a linear response for thrombin in the range of 7.5 pM to 75 pM and a detection limit of 4.5 pM. The aptasensor was regenerated by breaking the complex formed between the aptamer and thrombin using 2.0 M NaCl solution at 42 °C, showing its operation for different cycles. The interference response caused by main proteins in serum has been characterized.
Keywords: aptamer; thrombin; electrochemical impedance spectroscopy; labeless; adsorption aptamer; thrombin; electrochemical impedance spectroscopy; labeless; adsorption
This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

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MDPI and ACS Style

Ocaña, C.; Pacios, M.; del Valle, M. A Reusable Impedimetric Aptasensor for Detection of Thrombin Employing a Graphite-Epoxy Composite Electrode. Sensors 2012, 12, 3037-3048.

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