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Nanoscale. 2018 Mar 28;10(12):5550-5558. doi: 10.1039/c7nr03875e. Epub 2018 Mar 8.

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

Author information

1
Institut Laue-Langevin, 71 Avenue des Martyrs, 38000 Grenoble, France and European Synchrotron Radiation Facility, 71 Avenue des Martyrs, 38000 Grenoble, France. mitchell@esrf.eu.
2
Institut Laue-Langevin, 71 Avenue des Martyrs, 38000 Grenoble, France.
3
Univ. Grenoble Alpes, CEA, CNRS, IBS, F-38000 Grenoble, France.
4
European Synchrotron Radiation Facility, 71 Avenue des Martyrs, 38000 Grenoble, France. mitchell@esrf.eu.
5
European Molecular Biology Laboratory, 71 Avenue des Martyrs, 38000 Grenoble, France and Faculty of Natural Sciences, Keele University, Staffordshire, ST5 5BG, UK.
6
Institut Laue-Langevin, 71 Avenue des Martyrs, 38000 Grenoble, France and European Synchrotron Radiation Facility, 71 Avenue des Martyrs, 38000 Grenoble, France. mitchell@esrf.eu and School of Pharmacy, University College London, Brunswick Square, London, WC1N 1AX, UK.
7
Institut Laue-Langevin, 71 Avenue des Martyrs, 38000 Grenoble, France and Faculty of Natural Sciences, Keele University, Staffordshire, ST5 5BG, UK.
8
Department of Chemistry, Georgia State University, Atlanta, GA 30303, USA and Department of Pharmaceutical Organic Chemistry, Faculty of Pharmacy, Mansoura University, Mansoura, Egypt.
9
Department of Chemistry, Georgia State University, Atlanta, GA 30303, USA.
10
School of Pharmacy, University College London, Brunswick Square, London, WC1N 1AX, UK.
11
Univ. Grenoble Alpes, CNRS, CEA, INAC-SyMMES, 38000 Grenoble, France.
12
European Synchrotron Radiation Facility, 71 Avenue des Martyrs, 38000 Grenoble, France. mitchell@esrf.eu and Faculty of Natural Sciences, Keele University, Staffordshire, ST5 5BG, UK.

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.

PMID:
29517086
PMCID:
PMC5885265
DOI:
10.1039/c7nr03875e
[Indexed for MEDLINE]
Free PMC Article

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