2010/10/04 by Tomislav Vuletić, Vuletic, Tomislav, Sanja Dolanski Babić +11
Biochemistry, Genetics and Molecular Biology · Chemistry · Engineering · #DNA and Nucleic Acid Chemistry #Electrostatics and Colloid Interactions #FOS: Physical sciences #Nanopore and Nanochannel Transport Studies #Soft Condensed Matter (cond-mat.soft)
paper · pdf · doi:10.48550/arxiv.1010.0730
openalex publication_date 2010/10/04 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
We quantified the Manning free (uncondensed) counterions fraction \θ\nfor dilute solutions of rod-like polyions - 150bp DNA fragments, in very low\nsalt <0.05mM. Conductivity measurements of aqueous DNA solutions in the\nconcentration range 0.015\≤ c \≤ 8~mM (bp) were complemented by\nfluorescence correlation spectroscopy (FCS) measurements of the DNA polyion\ndiffusion coefficient Dp(c). We observed a crossover in the normalized\nconductivity \σ(c)/c which nearly halved across c=0.05-1 mM range,\nwhile Dp(c) remained rather constant, as we established by FCS. Analyzing\nthese data we extracted \θ(c)=0.30 - 0.45, and taking the Manning\nasymmetry field effect on polyelectrolyte conductivity into account we got\n\θ(c)=0.40-0.60. We relate the \θ(c) variation to gradual DNA\ndenaturation occuring, in the very low salt environment, with the decrease in\nDNA concentration itself. The extremes of the experimental \θ(c) range\noccur towards the highest, above 1 mM and the lowest, below 0.05 mM, DNA\nconcentrations, and correspond to the theoretical \θ values for dsDNA and\nssDNA, respectively. Therefore, we confirmed Manning condensation and\nconductivity models to be valuable in description of dilute solutions of\nrod-like polyions.\n