A new paradigm for charge transport in DNA
The work on "Backbone Mediated Electrical Transport in a Double-Stranded DNA" by Sourav Kundu and Siddhartha Lal got published in Physical Review E.
In the field of DNA nanotechnology, the prevailing understanding of charge transport in double- stranded DNA is that it occurs through pi-stacked nitrogen bases of the double helix. This has, however, been challenged in recent experiments by Zhuravel et. al. (Nat. Nanotech. 15, 836, 2020), suggesting instead that electronic transport obtains through the backbone channels. The striking experimental observation is that the presence of two local disconnections (labelled as “nicks” by the authors), one on either of the two backbones, causes the current passing through the DNA to vanish altogether.
To investigate this further, we studied the charge transport properties of three DNA sequences (periodic GC, periodic AT, and random ATGC) using a tight-binding model where backbones act as the main conduction channels. Our analysis, based on Green’s function method, focused on single- particle density of states and localization properties of DNA with nicks along the backbone channels. We also examined the impact of nicks on current-voltage response using the Landauer-Buttiker formalism in a two-terminal setup. Our results show that the periodic GC sequence exhibits metallic behaviour, while the periodic AT and random ATGC sequences are insulating. Interestingly, a single nick on the upper backbone of the periodic GC sequence has little effect on electronic transport, but adding a second nick on the lower backbone completely suppresses the current.
This behaviour is consistent regardless of nick positions or electrode arrangement. Analysis of the position-dependent probability distribution of the zero-energy electronic wave-function suggests that the insulation mechanism arises from a unique quantum interference of the electronic wave- function from the two nicks. Identical conclusions are obtained for the periodic AT and random ATGC sequences in their conducting regimes (obtained above a threshold voltage). In this way, our study opens the door towards further experimental and theoretical investigations of DNA nanotechnology that exploit the backbone conduction mechanism.
Journal Reference: Phys. Rev. E 112, 014401 (2025).
https://journals.aps.org/pre/abstract/10.1103/8xkb-rnzy
https://doi.org/10.1103/8xkb-rnzy
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Posted on: August 29th, 2025