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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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Optimization of the concentration of the blocking agent, PEG. Uncertainty values corresponding to replicated experiments (n = 5).
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f4-sensors-12-03037: Optimization of the concentration of the blocking agent, PEG. Uncertainty values corresponding to replicated experiments (n = 5).

Mentions: To minimize any possible nonspecific adsorption onto the electrode surface, polyethylene glycol (PEG) was used as the blocking agent. As shown in Figure 4, and like the previous case, there was an increase in resistance until the value of 40 mM of PEG where the saturation value is reached. Therefore, the optimal concentration of blocking agent was chosen as 40 mM.


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

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

Optimization of the concentration of the blocking agent, PEG. Uncertainty values corresponding to replicated experiments (n = 5).
© Copyright Policy
Related In: Results  -  Collection

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

f4-sensors-12-03037: Optimization of the concentration of the blocking agent, PEG. Uncertainty values corresponding to replicated experiments (n = 5).
Mentions: To minimize any possible nonspecific adsorption onto the electrode surface, polyethylene glycol (PEG) was used as the blocking agent. As shown in Figure 4, and like the previous case, there was an increase in resistance until the value of 40 mM of PEG where the saturation value is reached. Therefore, the optimal concentration of blocking agent was chosen as 40 mM.

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