DNA under voltage: Molecules detach from surfaces at the push of a button
With its extremely fine pinpoint, an atomic force miscroscope (AFM) can pick up and analyze a single molecule. This feature was used by biophysicists of the excellence cluster Nanosystems Initiative Munich (NIM), at the chair of Professor Hermann Gaub at the Ludwig Maximilian University of Munich, in order to determine how firmly DNA molecules stick to certain surfaces. In doing so, the scientists realized that voltage can have an effect on whether a molecule sticks to a surface or is repelled. Thus the interaction between a surface and DNA molecules can be controlled by the push of a button, which is an interesting prospect for many methods used in bioanalytics. This voltage-dependent adhesion does not only apply to DNA molecules, but also to other biopolymers, such as proteins or polysaccharides. (Nature Nanotechnology online, December 20, 2009)
For the analysis, a DNA molecule sticking to an AFM pinpoint was brought into contact with a gold-coated electrode, to which voltages of different levels were applied successively. By doing so, the researchers were the first to determine by means of an AFM how much force is required to redetach a single molecule from the electrode. The inherently negatively charged DNA molecule stuck firmly to the surface, when the surface was positively charged by voltage. The molecule was not able to adhere to a negatively charged electrode.
The possible applications utilizing this effect by far exceed its use in analytics. The vision of the Munich research team is that of an electrically switchable adhesive. While most conventional adhesives create irreversible connections after curing, using the newly discovered method, the adhesive bond could be switched on and off.
The results of this research are presented in the current Nature Nanotechnology online edition. They were achieved by the excellence cluster team of the Nanosystems Initiative Munich (NIM), whose goal is to explore, develop, and deliver functional nanostructures for applications in medicine and information processing (NIM).
„Electrically controlled DNA adhesion“
Matthias Erdmann, Ralf David, Ann Fornof, Hermann E. Gaub
Nature Nanotechnology online, December 20, 2009
Professor Hermann Gaub
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