Phase Association and Binding Energetics of Swcnts into Phospholipid Langmuir Monolayers

Single-walled carbon nanotubes (SWCNTs) have been identified as promising candidates for targeted drug delivery due to their low toxicity and ability to be functionalized using various bioactive groups. It is currently undetermined what mechanical and biological mechanism(s) are responsible for uptake into cells. We have used dispersed pristine SWCNTs to study mechanisms responsible for cellular uptake using cellular systems and in vitro model membrane systems. Fluorescence lifetime imaging microscopy (FLIM) of RhoB-GFP, a marker of endocytosis, shows functional spatial and temporal localization of endosomes with SWCNTs. Results demonstrate an increase in the number of endosomes after SWCNTs exposure indicating a stimulation of endocytosis. Measurements of SWCNT on artificial tethered bilayer membrane systems have shown no change in membrane capacitance indicating no penetration or disruption of membranes by SWCNTs. Preliminary results with Langmuir monolayers of lipids exposed to SWCNTs shows no significant increase in surface pressure from the control also indicating no significant uptake of SWCNTs. In sum, results support cellular mediated endocytosis of SWCNTs as the preferred mechanism for cellular uptake.