Chiral Sorting of Carbon Nanotubes using Tripeptides

Carbon nanotubes have many applications in different industries, but in order to utilize them efficiently they must be separated between their different types. Previous techniques such as chromatography, aqueous two-phase extraction, and DNA based sorting have been used as sorting modalities to either separate the individual chirality or to differentiate between the two primary types of carbon nanotubes, metallic and semiconducting. This project proposes a new sorting method using tripeptides to sort through the different types of single-walled carbon nanotubes. Based off of a previous study on molecular dynamics simulations, four tripeptides are identified for this study: Aspartic Acid-Glycine-Tyrosine (DGY0, Threonine-Glycine-Tyrosine (TGY), Threonine-Glycine-Lysine (TGK), and Asparagine-Glycine-Glutamic Acid (NGE). But first, in order to implement the use of tripeptides, the single-walled carbon nanotubes (SWCNTs) need to be properly dispersed without the use of a surfactant to avoid any interference from the surfactant molecules. Here we created a successful dispersion protocol without the use of a surfactant as well as the preliminary experiments and data from UV/ Vis spectra for the four tripeptide controls, carbon nanotubes control and tripeptide/ carbon nanotube dispersions. It is found that during the protocol testing, DGY was able to interact and pull the SWCNTs into the supernatant, but did not interact with them during the implementation phase. TGY had an interaction with ~11.8% and ~22.2% with the C3 peak in the supernatant with the vials held at room temperature and in an incubator, respectively. TGK also had an interaction with ~3.5% and .6% of the C1 peak, ~5.2% and ~8.6% of the C3 peak, as well as ~6.5% and ~9.8% of the C4

peak with the vials held at room temperature and in an incubator, respectively. Unfortunately, NGE didn’t show as promising results as the other tripeptides.