Surface patterning of carbon nanotubes can enhance their penetration through a phospholipid bilayer

TL;DR

Surface patterning of carbon nanotubes with biomolecules can significantly lower the energy barrier for membrane penetration, potentially enhancing their ability to translocate through phospholipid bilayers.

Contribution

This study demonstrates that surface patterning of carbon nanotubes reduces free energy barriers during membrane crossing, a novel insight into nanotube-membrane interactions.

Findings

Patterned nanotubes exhibit lower and more constant free energy during bilayer penetration.

Surface patterning may facilitate nanotube transduction through cell membranes.

Self-assembly of biomolecules on nanotubes influences their membrane crossing ability.

Abstract

Nanotube patterning may occur naturally upon the spontaneous self-assembly of biomolecules onto the surface of single-walled carbon nanotubes (SWNTs). It results in periodically alternating bands of surface properties, ranging from relatively hydrophilic to hydrophobic, along the axis of the nanotube. Single Chain Mean Field (SCMF) theory has been used to estimate the free energy of systems in which a surface patterned nanotube penetrates a phospholipid bilayer. In contrast to un-patterned nanotubes with uniform surface properties, certain patterned nanotubes have been identified that display a relatively low and approximately constant system free energy (10 kT) as the nanotube traverses through the bilayer. These observations support the hypothesis that the spontaneous self-assembly of bio-molecules on the surface of SWNTs may facilitate nanotube transduction through cell membranes.