Electromechanical effects on nanotube formation from lipid membranes

The formation of nanotubes from lipid membranes permits characterization of the resistance of the membrane to curvature changes, a fundamental material property. Current theoretical models of nanotube formation do not consider potential effects that could arise from an applied electric field. A finding, discovered using atomic force microscopy, that voltage induces membrane movement (Zhang et al., 2001) necessitates inclusion of an electromechanical energy in the thermodynamic description of nanotube formation. This energy is expressed as the product of the electric field, the curvature of the membrane and an electromechanical coupling coefficient. Inclusion of this term in the full thermodynamic potential results in constitutive equations applicable to tether experiments on lipid vesicles. These equations predict electric fields can have a significant and measurable effect on the behavior of nanotubes. The analysis motivates new experiments to measure the magnitude of the flexoelectric coefficient in giant liposomes.