Long-Range Charge Transport In DNA | Chemical & Engineering News
Volume 92 Issue 44 | p. 40 | Concentrates
Issue Date: November 3, 2014

Long-Range Charge Transport In DNA

Method measures charge transport in individual G-quadruplex molecules over distances longer than 100 nm
Department: Science & Technology
News Channels: Biological SCENE, Materials SCENE, Nano SCENE
Keywords: DNA, G-Quadruplex, charge transport

DNA molecules are attractive for molecular electronics because of their potential to self-assemble into programmed devices and circuits. But previous work on charge transport in DNA has yielded seemingly contradictory results, and long-range charge transport hasn’t been demonstrated—until now. Gideon I. Livshits, a graduate student with Danny Porath at the Hebrew University of Jerusalem, and coworkers have now measured long-range charge transport in single G-quadruplex DNA molecules, a type of DNA molecule that consists of stacked guanine tetrads (Nat. Nanotechnol. 2014, DOI: 10.1038/nnano.2014.246). The DNA was synthesized by Alexander B. Kotlyar’s research group at Tel Aviv University. The team deposits gold electrodes with sharp, well-defined edges on DNA molecules adsorbed on a flat mica surface. Then they bring a metal-coated atomic force microscope tip into contact at various points along the DNA to measure the current response to an applied voltage. Those currents range from tens of picoamperes to more than 100 pA over distances of 30 nm to more than 100 nm. Computational modeling suggests that charge transport occurs via hopping between multitetrad blocks.

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A circuit featuring gold electrodes can measure charge transport in G-quadruplex DNA molecules adsorbed on mica. In the AFM image, the wirelike structures are DNA molecules and the gold electrode is on the left.
Credit: Nat. Nanotechnol.
AFM image of G-quadruplex DNA and a gold electrode on a mica surface.
 
A circuit featuring gold electrodes can measure charge transport in G-quadruplex DNA molecules adsorbed on mica. In the AFM image, the wirelike structures are DNA molecules and the gold electrode is on the left.
Credit: Nat. Nanotechnol.
 
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