Understanding charge transport in DNA molecules is a long-standing problem of fundamental importance across disciplines1,2. It is also of great technological interest due to DNA’s ability to form versatile and complex programmable structures. Charge transport in DNA-based junctions has been reported using a wide variety of set-ups2–4, but experiments so far have yielded seemingly contradictory results that range from insulating5–8 or semiconducting9,10 to metallic-like behaviour11. As a result, the intrinsic charge transport mechanism in molecular junction set-ups is not well understood, which is mainly due to the lack of techniques to form reproducible and stable contacts with individual long DNA molecules. Here we report charge-transport measurements through single 30-nm-long double-stranded DNA (dsDNA) molecules with an experimental set-up that enables us to address individual molecules repeatedly and to measure the current–voltage characteristics from 5 K up to room temperature. Strikingly, we observed very high currents of tens of nanoamperes, which flowed through both homogeneous and non-homogeneous base-pair sequences. The currents are fairly temperature independent in the range 5–60 K and show a power-law decrease with temperature above 60 K, which is reminiscent of charge transport in organic crystals. Moreover, we show that the presence of even a single discontinuity (‘nick’) in both strands that compose the dsDNA leads to complete suppression of the current, which suggests that the backbones mediate the long-distance conduction in dsDNA, contrary to the common wisdom in DNA electronics2–4.
Bibliographical noteFunding Information:
This research was supported by the Israel Science Foundation (ISF grant nos. 1589/14 and 2556/17) and by the Minerva Centre for Bio-Hybrid Complex Systems. D.P. thanks the Etta and Paul Schankerman Chair of Molecular Biomedicine. G.P. and S.S.S. acknowledge financial support from the University of Cyprus PhD grants and J.C.C. from the Spanish MINECO (contract no. FIS2017-84057-P). V.G. acknowledges the support of Toyota Research Institute under the auspices of which some aspects of the DFT-FE package relevant to this work were developed. L.A.Z. thanks financial support from the University of Seville through the VI PPIT-US program. This paper and work are dedicated to the memory of Professor Joseph Sperling, who passed away during the performance of this research.
© 2020, The Author(s), under exclusive licence to Springer Nature Limited.