How long a functionalized carbon nanotube can passively penetrate a lipid membrane

We explore with Molecular Dynamics simulations and a statistical model, the ability of carbon nanotubes to be internalized into a model lipid bilayer as a function of their length. The hydrophobicity is one of the key factors responsible for the insertion process. The membrane asymmetry is also needed to drive a complete translocation. Our data demonstrates that shorter nanotubes have a stronger propensity to passively penetrate the bilayer and reach the cytoplasm. Carbon nanotubes excretion appears mostly impossible whatever their length. (C) 2012 Elsevier Ltd. All rights reserved.