Spontaneous Penetration of Carbon Nanotubes through Lipid Bilayers: A Computational Perspective

Carbon nanotubes (CNTs) have been widely explored for
applications
ranging from drug delivery to energy conversion. To evaluate their
potential as drug-delivery agents, it is essential to understand the
molecular mechanisms governing their interactions with, and possible
transport across, cell membranes. Molecular dynamics (MD) simulations
provide a powerful framework for probing these processes at molecular
resolution. In this study, we investigate the spontaneous membrane
insertion and deep penetration of pristine CNTs (p-CNTs) using the weighted ensemble (WE) method combined with all-atom
MD simulations. Two p-CNTs with similar diameters
but different lengths were examined to elucidate how nanotube length
influences membrane-interaction behavior. Both p-CNTs
readily insert into the hydrophobic core of the membrane; however,
they exhibit distinct behaviors near the lower leaflet. Although neither p-CNT fully escapes into the opposite aqueous phase due
to strong hydrophobic interactions, the WE approach enables detailed
characterization of their penetration pathways and the associated
free-energy landscape within the bilayer.