Wrinkling and electroporation of giant vesicles in the gel phase†

Electric pulses applied to fluid phospholipid vesicles deform them and can induce the formation of pores, which reseal after the end of the pulse. The mechanical and rheological properties of membranes in the gel phase differ significantly from those of fluid membranes, thus a difference in the vesicle behavior in electric fields is expected. However, studies addressing this problem are scarce. Here, we investigate the response of giant gel-phase vesicles to electric pulses and resolve the dynamics of deformation with microsecond resolution. We find that the critical transmembrane potential leading to poration is several times higher as compared to that of fluid membranes. In addition, the resealing of the pores is arrested. Interestingly, the vesicle shapes change from ellipsoidal to spherocylindrical during the electric pulse and the membrane becomes periodically wrinkled with ridges aligned with the field direction and wavelengths in the micrometre range. Such membrane wrinkling has not been reported previously. The corrugations comply with universal laws of wrinkling of surfaces with lengthscale dimensions from nanometres to metres.