Long-Range Charge Transport In DNA

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.