Dependence of DNA Persistence Length on Ionic Strength of Solutions with Monovalent and Divalent Salts: A Joint Theory–Experiment Study

• DOI: 10.1021/acs.macromol.5b00735
• Publication Date: 2015-05-29T12:02:02Z
• Authors: Annaël Brunet; Catherine Tardin; Laurence Salomé; Philippe Rousseau; Nicolas Destainville; Manoel Manghi
• Keywords: Persistence length; Divalent; Counterion Condensation; Particle (ecology)

Using high-throughput tethered particle motion single-molecule experiments, the double-stranded DNA persistence length, Lp, is measured in solutions with Na+ and Mg2+ ions of various ionic strengths, I. Several theoretical equations for Lp(I) are fitted to experimental data, but no decisive theory found which fits all Lp values two ion valencies. Properly extracted from trajectory using simulations, varies 30 55 nm, comparable previous results. For Na+-only case, an increasing concave function I–1, well by Manning's electrostatic stretching approach, not classical Odjik–Skolnick–Fixman theories or without counterion condensation. With added ions, shows a marked decrease at low I, interpreted as ion–ion correlation effect, almost linear law proposed variational approach.