The pathogenicity of carbon nanotubes has been linked in some studies to their one-dimensional geometry coupled to long fiber length, which hinders complete cellular internalization. Biophysical models have been proposed for the cell entry of spheres and elliptical nanostructures, but one-dimensional nanomaterials are a more complex case.  This work combines in vitro experiments with course-grained molecular dynamics simulations of complete lipid bilayer segments to study the molecular interactions that initiate nanotube internalization.   Uptake is shown to occur when the rounded end caps mimic particles and initiate endocytosis through receptor binding, membrane wrapping, and tip-first entry.  Asymmetric strain in the membrane causes tube rotation to a near-vertical state, in which the cells cannot sense or respond to the total tube length.  The implications of this tip-entry mechanism will be discussed for cell frustration, the activation of toxicity pathways, and the possible safe design of nanotubes through tip reformulation.

Tip entry mechanisms for carbon nanotube endocytosis and cellular frustration

243rd National Meeting (2012)

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