Issue 12, 2018

Dynamic self-assembly of DNA minor groove-binding ligand DB921 into nanotubes triggered by an alkali halide

Abstract

We describe a novel self-assembling supramolecular nanotube system formed by a heterocyclic cationic molecule which was originally designed for its potential as an antiparasitic and DNA sequence recognition agent. Our structural characterisation work indicates that the nanotubes form via a hierarchical assembly mechanism that can be triggered and tuned by well-defined concentrations of simple alkali halide salts in water. The nanotubes assembled in NaCl have inner and outer diameters of ca. 22 nm and 26 nm respectively, with lengths that reach into several microns. Our results suggest the tubes consist of DB921 molecules stacked along the direction of the nanotube long axis. The tubes are stabilised by face-to-face π–π stacking and ionic interactions between the charged amidinium groups of the ligand and the negative halide ions. The assembly process of the nanotubes was followed using small-angle X-ray and neutron scattering, transmission electron microscopy and ultraviolet/visible spectroscopy. Our data demonstrate that assembly occurs through the formation of intermediate ribbon-like structures that in turn form helices that tighten and compact to form the final stable filament. This assembly process was tested using different alkali–metal salts, showing a strong preference for chloride or bromide anions and with little dependency on the type of cation. Our data further demonstrates the existence of a critical anion concentration above which the rate of self-assembly is greatly enhanced.

Graphical abstract: Dynamic self-assembly of DNA minor groove-binding ligand DB921 into nanotubes triggered by an alkali halide

Supplementary files

Article information

Article type
Paper
Submitted
01 Jun 2017
Accepted
31 Jan 2018
First published
08 Mar 2018
This article is Open Access
Creative Commons BY-NC license

Nanoscale, 2018,10, 5550-5558

Dynamic self-assembly of DNA minor groove-binding ligand DB921 into nanotubes triggered by an alkali halide

R. Mizuta, J. M. Devos, J. Webster, W. L. Ling, T. Narayanan, A. Round, D. Munnur, E. Mossou, A. A. Farahat, D. W. Boykin, W. D. Wilson, S. Neidle, R. Schweins, P. Rannou, M. Haertlein, V. T. Forsyth and E. P. Mitchell, Nanoscale, 2018, 10, 5550 DOI: 10.1039/C7NR03875E

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