Functionalizations and biological applications of single-walled carbon nanotubes and graphite systems
Price, Brandi Katherine
Tour, James M.
Doctor of Philosophy
Environmentally friendly solvents including water and ionic liquids have been used as a medium to functionalize singe-walled carbon nanotubes (SWCNTs). Previously, in order to obtain individual functionalized SWCNTs, harsh chemicals or reaction conditions were necessary. The environmentally friendly solvents have now been demonstrated to yield individual and small bundles of SWCNTs by utilizing established diazonium chemistry in ionic liquids or water. The ionic liquid-based method has also been shown to be effective for functionalization of expanded graphite, which yields small stacks of graphite sheets only 7 nm in height, while dramatically increasing the dispersibility of the graphite in organic solvents. Aggressively oxidized and shortened, or ultra short SWCNTs (US-SWCNTs), have been used as the base material for many studies. US-SWCNTs were associated to polymers through acid/base interactions. The amine-based polymer was used to group together iron atoms and after subsequent processing, form a catalyst seed for SWCNT growth. The seeded US-SWCNTs were then shown to further grow in length under hydrocarbon feed conditions. US-SWCNTs have been used to produce a nanovector scaffold through PEGylation to produce PEG-US-SWCNTs. The PEG-US-SWCNT nanovector has been found to sequester fluorescent tags. The sequestered material was used in a multistage delivery system for therapeutics and imaging. The PEG-US-SWCNTs were discovered to also sequester proteins. The behavior of the proteins was analyzed and their activity in vitro was monitored. The proteins retained their activity and were shown to activate cell pathways.