(166h) Molecular Dynamics Simulations Reveal Single-Stranded DNA (ssDNA) Forms Ordered Structures upon Adsorbing Onto Single-Walled Carbon Nanotubes (SWCNTs) | AIChE

(166h) Molecular Dynamics Simulations Reveal Single-Stranded DNA (ssDNA) Forms Ordered Structures upon Adsorbing Onto Single-Walled Carbon Nanotubes (SWCNTs)

Authors 

Hinkle, K. R. - Presenter, National Institute of Standards and Technology
The unique optical and electrical properties possessed by single walled-carbon nanotubes (SWCNTs) make them attractive for a number of applications. Separation and purification of SWCNTs into uniform populations is an ongoing challenge which must be solved before their widespread use is realized. Many separation techniques address this problem through use of surfactants in order to suspend the tubes in aqueous media and then apply other approaches such as aqueous two-phase extraction (ATPE) to sort the dispersed SWCNTs by their physiochemical properties. Single-stranded DNA (ssDNA) has proven to be an effective dispersant that shows sequence-specific behavior during separation. While the nature of this specificity is not well understood, we hypothesize that the partitioning of certain ssDNA-SWCNT complexes only occurs due to narrow, non-overlapping distributions of solvation energy between different pairs. Contrastingly, inseparable complexes are caused by overlapping solvation energy distributions which would partition in similar fractions. In this talk, we use replica exchange molecular dynamics (REMD) simulations to show how ordered ssDNA structures arise after surface adsorption which could lead to the narrow free energy distributions predicted. We also investigate the effect that SWCNT chirality plays in regards to the ssDNA structures and how these complexes may be stabilized by inter- and intra-strand ssDNA hybridization. An investigation into the wrapping structures presented by different sequence-chirality pairs may give further insight into this phenomenon and allow for the prediction of assemblies which would drive separation.