Nanoconfinement-enhanced conformational response of single DNA molecules to changes in ionic environment

Walter Reisner, J. P. Beech, Niels Bent Larsen, Henrik Flyvbjerg, Anders Kristensen, J. O. Tegenfeldt

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    Abstract

    We show that the ionic environment plays a critical role in determining the configurational properties of DNA confined in silica nanochannels. The extension of DNA in the nanochannels increases as the ionic strength is reduced, almost tripling over two decades in ionic strength for channels around 100×100 nm in dimension. Surprisingly, we find that the variation of the persistence length alone with ionic strength is not enough to explain our results. The effect is due mainly to increasing self-avoidance created by the reduced screening of electrostatic interactions at low ionic strength. To quantify the increase in self-avoidance, we introduce a new parameter into the de Gennes theory: an effective DNA width that gives the increase in the excluded volume due to electrostatic repulsion.
    Original languageEnglish
    JournalPhysical Review Letters
    Volume99
    Issue number5
    Pages (from-to)058302
    ISSN0031-9007
    DOIs
    Publication statusPublished - 2007

    Bibliographical note

    Copyright 2007 American Physical Society

    Keywords

    • CONDENSATION
    • CHANNELS
    • POLYMERS
    • DOUBLE-STRANDED DNA
    • EFFECTIVE DIAMETER
    • DYNAMICS

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