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

Ocaña C, Pacios M, del Valle M - Sensors (Basel) (2012)

Bottom Line: 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.

View Article: PubMed Central - PubMed

Affiliation: 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.

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(a) Scheme of the manufacture of graphite-epoxy composite electrodes, (b) Steps of the biosensing procedure.
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f1-sensors-12-03037: (a) Scheme of the manufacture of graphite-epoxy composite electrodes, (b) Steps of the biosensing procedure.

Mentions: Graphite epoxy composite (GEC) electrodes used were prepared using a PVC tube body (6 mm i.d.) and a small copper disk soldered at the end of an electrical connector, as shown on Figure 1(a). The working surface is an epoxy-graphite conductive composite, formed by a mixture of graphite (20%) and epoxy resin (80%), deposited on the cavity of the plastic body [15,16]. The composite material was cured at 80 °C for 3 days. Before each use, the electrode surface was moistened with MilliQ water and then thoroughly smoothed with abrasive sandpaper and finally with alumina paper (polishing strips 301044-001, Orion) in order to obtain a reproducible electrochemical surface.


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

Ocaña C, Pacios M, del Valle M - Sensors (Basel) (2012)

(a) Scheme of the manufacture of graphite-epoxy composite electrodes, (b) Steps of the biosensing procedure.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3376577&req=5

f1-sensors-12-03037: (a) Scheme of the manufacture of graphite-epoxy composite electrodes, (b) Steps of the biosensing procedure.
Mentions: Graphite epoxy composite (GEC) electrodes used were prepared using a PVC tube body (6 mm i.d.) and a small copper disk soldered at the end of an electrical connector, as shown on Figure 1(a). The working surface is an epoxy-graphite conductive composite, formed by a mixture of graphite (20%) and epoxy resin (80%), deposited on the cavity of the plastic body [15,16]. The composite material was cured at 80 °C for 3 days. Before each use, the electrode surface was moistened with MilliQ water and then thoroughly smoothed with abrasive sandpaper and finally with alumina paper (polishing strips 301044-001, Orion) in order to obtain a reproducible electrochemical surface.

Bottom Line: 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.

View Article: PubMed Central - PubMed

Affiliation: 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.

Show MeSH
Related in: MedlinePlus