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Sensors (Basel). 2012;12(3):3037-48. doi: 10.3390/s120303037. Epub 2012 Mar 6.

A reusable impedimetric aptasensor for detection of thrombin employing a graphite-epoxy composite electrode.

Author information

1
Department of Chemistry, Universitat Autònoma de Barcelona, Bellaterra 08193, Spain. cristina.ocana@uab.es

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:

adsorption; aptamer; electrochemical impedance spectroscopy; labeless; thrombin

PMID:
22736991
PMCID:
PMC3376577
DOI:
10.3390/s120303037
[Indexed for MEDLINE]
Free PMC Article
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