Nanoscale Structure and Elasticity of Pillared DNA Nanotubes

Joshi, Himanshu and Kaushik, Atul and Seeman, Nadrian C and Maiti, Prabal K (2016) Nanoscale Structure and Elasticity of Pillared DNA Nanotubes. In: ACS NANO, 10 (8). pp. 7780-7791.

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Abstract

We present an atomistic model of pillared DNA nanotubes (DNTs) and their elastic properties which will facilitate further studies of these nanotubes in several important nano technological and biological applications. In particular, we introduce a computational design to create an atomistic model of a 6-helix DNT (6HB) along with its two variants, 6HB flanked symmetrically with two double helical DNA pillars (6HB+2) and 6HB flanked symmetrically by three double helical DNA pillars (6HB+3). Analysis of 200 ns all-atom simulation trajectories in the presence of explicit water and ions shows that these structures are stable and well behaved in all three geometries. Hydrogen bonding is well maintained for all variants of 6HB DNTs. From the equilibrium bending angle distribution, we calculate the persistence lengths of these tubes. The measured persistence lengths of these nanotubes are similar to 10 pm, which is 2 orders of magnitude larger than that of dsDNA. We also find a gradual increase of persistence length with an increasing number of pillars, in quantitative agreement with previous experimental findings. To have a quantitative understanding of the stretch modulus of these tubes, we carried out nonequilibrium steered molecular dynamics (SMD). The linear part of the force extension plot gives a stretch modulus in the range 6500 pN for 6HB without pillars, which increases to 11 000 pN for tubes with three pillars. The values of the stretch modulus calculated using contour length distribution obtained from equilibrium MD simulations are similar to those obtained from nonequilibrium SMD simulations. The addition of pillars makes these DNTs very rigid.

Item Type:	Journal Article
Publication:	ACS NANO
Additional Information:	Copy right for this article belongs to the AMER CHEMICAL SOC, 1155 16TH ST, NW, WASHINGTON, DC 20036 USA
Department/Centre:	Division of Physical & Mathematical Sciences > Physics
Date Deposited:	08 Oct 2016 07:20
Last Modified:	08 Oct 2016 07:20
URI:	http://eprints.iisc.ac.in/id/eprint/54941

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