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Int. J. Mol. Sci. 2017, 18(11), 2484; https://doi.org/10.3390/ijms18112484

Development of An Impedimetric Aptasensor for the Detection of Staphylococcus aureus

1
Institut für Bioprozess- und Analysenmesstechnik e.V., 37308 Heilbad Heiligenstadt, Germany
2
UFZ – Helmholtz Centre for Environmental Research, 06120 Halle, Germany
3
UFZ – Helmholtz Centre for Environmental Research, 04318 Leipzig, Germany
*
Author to whom correspondence should be addressed.
Received: 31 October 2017 / Revised: 13 November 2017 / Accepted: 15 November 2017 / Published: 21 November 2017
(This article belongs to the Special Issue Aptamers)
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Abstract

In combination with electrochemical impedance spectroscopy, aptamer-based biosensors are a powerful tool for fast analytical devices. Herein, we present an impedimetric aptasensor for the detection of the human pathogen Staphylococcus aureus. The used aptamer targets protein A, a surface bound virulence factor of S. aureus. The thiol-modified protein A-binding aptamer was co-immobilized with 6-mercapto-1-hexanol onto gold electrodes by self-assembly. Optimization of the ratio of aptamer to 6-mercapto-1-hexanol resulted in an average density of 1.01 ± 0.44 × 1013 aptamer molecules per cm2. As shown with quartz crystal microbalance experiments, the immobilized aptamer retained its functionality to bind recombinant protein A. Our impedimetric biosensor is based on the principle that binding of target molecules to the immobilized aptamer decreases the electron transfer between electrode and ferri-/ferrocyanide in solution, which is measured as an increase of impedance. Microscale thermophoresis measurements showed that addition of the redox probe ferri-/ferrocyanide has no influence on the binding of aptamer and its target. We demonstrated that upon incubation with various concentrations of S. aureus, the charge-transfer resistance increased proportionally. The developed biosensor showed a limit of detection of 10 CFU·mL−1 and results were available within 10 minutes. The biosensor is highly selective, distinguishing non-target bacteria such as Escherichia coli and Staphylococcus epidermidis. This work highlights the immense potential of impedimetric aptasensors for future biosensing applications. View Full-Text
Keywords: aptamer; staphylococcal protein A; label-free; biosensing techniques; rapid detection; self-assembly; limit of detection; protein binding; ferri-/ferrocyanide; gold electrode aptamer; staphylococcal protein A; label-free; biosensing techniques; rapid detection; self-assembly; limit of detection; protein binding; ferri-/ferrocyanide; gold electrode
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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 (CC BY 4.0).
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Reich, P.; Stoltenburg, R.; Strehlitz, B.; Frense, D.; Beckmann, D. Development of An Impedimetric Aptasensor for the Detection of Staphylococcus aureus. Int. J. Mol. Sci. 2017, 18, 2484.

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