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Huck C.,Institute of Nano and Biotechnologies INB | Backer M.,Institute of Nano and Biotechnologies INB | Muller F.,Experimental PhysicsSaarland University66123SaarbruckenGermany | Grandthyll S.,Experimental PhysicsSaarland University66123SaarbruckenGermany | And 3 more authors.
Physica Status Solidi (A) Applications and Materials Science | Year: 2015

In this work, we present a reduced graphene oxide-based impedimetric histamine biosensor. Histamine as a bioamine mediates immune-modulatory effects in acute inflammatory and allergic reactions. In a proof-of-principle approach, the low-cost sensor platform determines low concentrations of histamine in buffer solution with an impedimetric readout technique. As a sensor platform we used ultra-thin graphene oxide lines fabricated by a simple soft-lithographic approach. The lines of about 20μm width were characterised by atomic force microscopy and scanning electron microscopy. Reduction of graphene oxide to a conductive transducer material was performed by a rapid thermal protocol in inert atmosphere. The reduction process was monitored by impedance spectroscopy and X-ray photoelectron spectroscopy. For our biosensor experiments we adopted a commonly-used protocol for surface plasmon resonance (SPR) detection of histamine. With our reduced graphene oxide platform we detected antigen-antibody binding events of histamine with concentrations of 0.1-1μM via impedance changes in a low frequency range. The results from the rGO sensors were comparable to the SPR detection. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Backer M.,Institute of Nano and Biotechnologies INB | Kramer F.,Institute of Nano and Biotechnologies INB | Huck C.,Institute of Nano and Biotechnologies INB | Poghossian A.,Institute of Nano and Biotechnologies INB | And 4 more authors.
Physica Status Solidi (A) Applications and Materials Science | Year: 2014

Planar and three-dimensional (3D) interdigitated electrodes (IDE) with electrode digits separated by an insulating barrier of different heights were electrochemically characterized and compared in terms of their sensing properties. Due to the impact of the surface resistance, both types of IDE structures display a non-linear behavior in low-ionic strength solutions. The experimental data were fitted to an electrical equivalent circuit and interpreted taking into account the surface-charge-governed properties. The effect of a charged polyelectrolyte layer electrostatically assembled onto the sensor surface on the surface resistance in solutions with different KCl concentration is studied. In case of the same electrode footprint, 3D-IDEs show a larger cell constant and a higher sensitivity to molecular adsorption than that of planar IDEs. The obtained results demonstrate the potential of 3D-IDEs as a new transducer structure for a direct label-free sensing of charged molecules. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

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