(142g) Single-Walled Carbon Nanotube Dispersion in a Complex Biological Medium

This research aims to examine the ability of Tryptic Soy Broth (TSB), a bacterial culture medium, to disperse single-walled carbon nanotubes (SWNT).  There has been notable research into how specific proteins and biological macromolecules interact with SWNT; however, relatively little is known about SWNT’s interactions with complex biological media frequently used in bacteriology.  The dispersions examined in this study were prepared via probe ultrasonication of SWNT and TSB mixtures in the 0.05 wt% to 0.1 wt% range at 60W for 30 minutes or settings that delivered equivalent energy.  These dispersions were centrifuged for 3 hours at 17,000 x g.  The resulting supernatants were analyzed via various methods including ultraviolet-visible spectroscopy and circular dichroism spectroscopy in order to characterize the ability of TSB to disperse SWNT.  Dried samples were analyzed with atomic force microscopy, scanning electron microscopy, optical microscopy and infrared spectroscopy in order gain additional insight into TSB-SWNT interactions.  These results combined with earlier work on SWNT-Lysozyme interactions suggest that π-π stacking interactions between SWNT and the amino acid tryptophan are a key factor in polypeptide based dispersion. The ability to disperse SWNT in biologically relevant media provides a starting point for further research to assess possible SWNT interactions with pathogenic bacteria without concerns about antimicrobial properties of the dispersion medium.