Nanoconfinement-enhanced conformational response of single DNA molecules to changes in ionic environment.
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 x 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.
Reisner
Walter
W
Danish Polymer Centre and Biosystems Department, Risø National Laboratory, Technical University of Denmark-DTU, DK-4000 Roskilde, Denmark.
Beech
Jason P
JP
Larsen
Niels B
NB
Flyvbjerg
Henrik
H
Kristensen
Anders
A
Tegenfeldt
Jonas O
JO
D004247:DNA; D007477:Ions; D008968:Molecular Conformation; D009994:Osmolar Concentration; D055672:Static Electricity
D007477:Ions; D004247:DNA