A novel separation strategy that has recently emerged for separating single-walled carbon nanotubes (SWCNTs) by chirality is the use of aqueous two-phase extraction (ATPE) in conjunction with single-stranded DNA (ssDNA) as a dispersant. It has been found experimentally that certain ssDNA sequences have greater binding affinity to specific SWCNT chiralities enabling efficient isolation of single species from the highly heterogeneous mixtures inherent to the synthesis process. The challenge in this has been the identification of ssDNA-SWCNT, sequence-chirality pairs that are optimal binders. This has led to a lot of immense amount of trial and error work on the experimental end to develop even a small library of matches.<br/><br/>In this talk, we describe a new protocol using molecular simulations and free energy perturbation (FEP) that can be used to quantify and rank the binding affinity of ssDNA-SWCNT pairs based on differences in their free energy of solvation. To test the method, we study the ssDNA-SWCNT binding process for both optimal and non-matching binding pairs and find that the ranking of ssDNA sequence binding affinity relative to specific SWCNT chiralities matches very well with experimental observations. We also study the effect of the relative concentration of ssDNA and use that information to quantify the effect of inter- and intra-strand ssDNA hybridization on the free-energy – this yields insight into the physics driving the stability of the binding process. Future work to use the new protocol to design optimal binding pairs will also be described.

Ranking binding affinity for ssDNA-wrapped single-walled carbon nanotube (SWCNTs) using free energy perturbation (FEP)

256th National Meeting (2018)

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.