From the double-stranded helix to the chiral nematic phase of B-DNA: a molecular model

Abstract

B-DNA solutions of suitable concentration form left-handed chiral nematic phases (cholesterics). Such phases have also been observed in solutions of other stiff or semiflexible chiral polymers; magnitude and handedness of the cholesteric pitch are uniquely related to the molecular features. In this work we present a theoretical method and a numerical procedure which, starting from the structure of polyelectrolytes, lead to the prediction of the cholesteric pitch. Molecular expressions for the free energy of the system are obtained on the basis of steric and electrostatic interactions between polymers; the former are described in terms of excluded volume, while a mean field approximation is used for the latter. Calculations have been performed for 130 bp fragments of B-DNA. The theoretical predictions provide an explanation for the experimental behavior, by showing the counteracting role played by shape and charge chirality of the molecule.

arXiv comment42 pages, 6 figures

References in corpus (4)

• Molecular Chirality and Chiral Parameters
• Attraction between DNA molecules mediated by multivalent ions
• Electrostatic Interaction between Long, Rigid Helical Macromolecules at All Interaxial Angles
• Adsorption of mono- and multivalent cat- and anions on DNA molecules

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• Generalized van der Waals theory for the twist elastic modulus and helical pitch of cholesterics
• Density Functional Theory for Chiral Nematic Liquid Crystals
• From rods to helices: evidence of a screw-like nematic phase
• Chiral Self-Assembly of Helical Particles
• Left or right cholesterics? A matter of helix handedness and curliness
• Chiral shape fluctuations and the origin of chirality in cholesteric phases of DNA origamis
• Cholesteric order in systems of helical Yukawa rods
• Spontaneous sense inversion in helical mesophases
• Incorporating particle flexibility in a density functional description of nematics and cholesterics
• Perturbative density functional methods for cholesteric liquid crystals
• Hierarchical bounding structures for efficient virial computations: Towards a realistic molecular description of cholesterics