HF radiofrequency exposure partially restores the dynamics of model membranes containing carbon nanotubes

Abstract

HF radiofrequency exposure and/or the presence of carbon nanotubes (CNT) induce modifications to the structure and dynamics of model membranes. These modifications were investigated by multinuclear NMR methods in various phospholipid membrane systems. CNTs were found to spontaneously integrate into the superficial layer of membranes at low temperatures; they did not interact with the terminal methyl group of the chains. The local order was increased from C10 to the plateau region of the acyl chain, whereas the local order in the depth was not significantly modified. A specific implication of the choline headgroup was found, resulting in an overall rigidification when CNTs were present. While low-level, athermal radiofrequency exposure in the HF band alone had no significant effect on membrane structure or dynamics, it did partially reverse the consequences of CNT interactions with the membrane by producing a new membrane structure, possibly consistent with gel- or cubic-phase formation.