A Dna That Conducts

Around 15 years ago, the idea of exploiting the self-repairing, self-organizing and selfreproduction properties of DNA to create nanoelectronic circuits was a dream of many researchers in the nanoscience community1,2. The vision triggered research activities all over the world3,4, but such devices never emerged. In fact, it proved difficult to deliver the most basic requirement: a reliable determination of the charge conduction capabilities of DNA over distances of at least several nanometres. As a result, the majority of researchers gave up, and, in the last decade, reports about successful charge transport in DNA have become sparse. Writing in Nature Nanotechnology, Alexander Kotlyar, Danny Porath and colleagues now provide a comprehensive study of one particular type of DNA molecule, and show that it can deliver reproducible long-range charge transport5. The results could revive interest in the field of DNA electronics and also spur development in polymer-based nanoelectronics more generally. Natural DNA consists of pairs of bases — guanine (G) and cytosine (C), and thymine (T) and adenosine (A) — that are stacked up to form a double-stranded helical structure. From theoretical and experimental studies, it is known that the charge conduction path in the molecule is formed by the electronic wavefunctions that extend perpendicular to the base planes and overlap with those of the neighbouring planes, forming what is known as a π-orbital system1–4. The overlap of the π orbitals depends sensitively on the relative orientation of the base planes and thus on the DNA structure6. However, the structure of DNA is extremely fragile and can undergo changes in response to its electrochemical environment and its interaction with an underlying substrate7. Such structural changes can alter the electronic properties of double-stranded DNA from a good conductor to an