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Attractive Interactions between DNA-Carbon Nanotube hybrids in Monovalent Salts



Ming Zheng, Xiangyun Qiu, Fuyou Ke, Raju Timsina, Constantine Y. Khripin


DNA-carbon nanotube (DNA-CNT) hybrids are nanometer-sized, highly-charged, rod-like molecules with complex surface chemistry, and their behaviors in aqueous solutions are governed by multifactorial interactions with both solvent and co-solutes. We have previously measured the force between DNA- CNTs as a function of their inter-axial distance in low monovalent salts where inter-hybrid electrostatic repulsion dominates. The characteristics of DNA-CNT forces were further shown to closely resemble that of double-stranded DNA (dsDNA) in low salts. However, contrasting behaviors emerge at elevated monovalent salts: DNA-CNT condenses spontaneously whereas dsDNA remains soluble. Here we report force-distance dependencies of DNA-CNT across wide-ranging monovalent salt concentrations. DNA-CNT force curves are observed to deviate from dsDNA curves above 300 mM NaCl, and the deviation grows with increasing salts. Most notably, DNA-CNT forces become net attractive above 1 M NaCl, whereas dsDNA forces are repulsive at all salt concentrations. We further discuss possible physical origins for the observed DNA-CNT attraction in monovalent salts, in consideration of the complex surface chemistry and unique polyelectrolyte property of DNA-CNT hybrids.
Journal of Physical Chemistry C


DNA-carbon nanotube hybrids, polyelectrolyte


Zheng, M. , Qiu, X. , Ke, F. , Timsina, R. and Khripin, C. (2016), Attractive Interactions between DNA-Carbon Nanotube hybrids in Monovalent Salts, Journal of Physical Chemistry C (Accessed April 23, 2024)
Created June 30, 2016, Updated March 17, 2017