High Resolution Carbon Nanotube Enantiomer Separation By Specific DNA Sequences

Carbon nanotubes (CNTs) have remarkable electrical, thermal, mechanical, and optical properties making them uniquely suited as fundamental building blocks for electronics and biomedical applications. However, CNT polydispersity has been one of the major challenges limiting their fundamental research and technological development. Polymer aqueous two-phase (ATP) extraction has been recently demonstrated as an effective technique to sort polydisperse nanotube material. The spontaneous partition of single-stranded DNA-wrapped single-wall carbon nanotubes (ssDNA-SWCNTs) in a given ATP system is strongly sequence-dependent and can be further modulated by salt and polymer additives to efficiently isolate single nanotube structures. Additionally, circular dichroism (CD) spectroscopy shows that purified semiconducting and metallic nanotubes are also enantiomer enriched. Separating CNT enantiomers is of great scientific interest since it provides important information into the mode of DNA binding and molecular recognition towards specific nanotube structures. In this work, we have conducted an exhaustive screening of a 12-mer DNA library using a specific DNA sequence pattern. To our surprise, this new pattern enabled the identification of a super-sequence which can recognize and separate both enantiomers of a single chirality (6,5) species in record high purity and yield in an ATP system.