Labelfree Detection of Biomolecular Interactions by Means of Field-Effect Transistor Devices

Sven Ingebrandt¹, Y. Han¹, M. Sakkari¹, M. Abouzar², A. Poghossian², M.J. Schöning², and Andreas Offenhäusser¹
¹Institute for Thin Films & Interfaces, Institute for Bio- and Chemosensors (ISG-2), Research Center Jülich, D-52425 Jülich, Germany, and
²Laboratory for Chemical Sensors and Biosensors, University of Applied Sciences Aachen, Division Jülich, D-52425 Jülich, Germany
e-mail: s.ingebrandt@fz-juelich.de
URL: http://www.ingebrandt.de

We are working on the development of a fully-electronic biomolecular sensor system. In all concepts biochemical sensing and perception reactions are used, which offer a high sensitivity and selectivity (e.g. DNA/DNA; DNA/RNA; protein/protein, antigen/antibody ...). A very prominent example is the DNA-chip. The so-called third generation of DNA-chips aims at a labelfree, fully electronic readout system. Binding events (e.g. DNA hybridisation, attachment of charged polyelectrolytes...) change the interface capacitance and the surface potential. Both effect are probed in parallel by our devices.

As first chip we developed a 16-channel field-effect transistor (FET) composed of fully encapsulated, microsized silicon chips and a costum-made, miniaturised amplifier system. To avoid signal alteration by side-effects a differential readout set-up should be used. For this purpose we developed an aligned microspotting system, using a high precision positioning and a commercial DNA spotting system. First tests to detect DNA hybridisation were successful with the chip. However, our FET system is not only limited to DNA detection. In future we will further miniaturise the sensitive spots towards nanodimensions to gain higher sensitivity of the sensors. Final goal will be the parallel detection from mixtures of various biomolecules to prove the possible application of the system in future bioanalysis.