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Abstract:
Increasing awareness of bioeffects and toxicity of nanomaterials interacting with cells puts in focus the mechanisms by which nanomaterials can cross lipid membranes. Apart from well-discussed energy-dependent endocytosis for large objects and passive diffusion through membranes by solute molecules, there can exist other translocation mechanisms based on physical principles. We show the importance of membrane tension on the translocation through lipid bilayers of ultra-short carbon nanotubes (USCNTs). By using a combination of a microfluidic setup and self-consistent mean field theory we observed that under membrane tension, USCNT inserted into a lipid bilayer may spontaneously nucleate an unstable local pore, allowing it to escape from the bilayer. We demonstrated that stretching of the membrane is essential for triggering this mechanism of translocation, and no translocation is observed at low membrane tension. For this purpose, a quantitative analysis of the kinetic pathway associated with USCNT translocation induced by tension was performed in a specially designed microfluidic device, simultaneously combining optical fluorescence microscopy and electrophysiological measurements. Important outcome of these findings is the identification of the way to control the nanomaterials translocation through lipid bilayer by membrane tension that can be useful in many practical applications.
