Membrane electroporation and electromechanical deformation of vesicles and cells

Abstract

Analysis of the reduced turbidity and absorbance relaxations of (*T ~/T 0 ) ( *A~/A 0 ) unilamellar lipid vesicles, doped with the diphenylhexatrienyl [ phosphatidylcholine (b-DPH pPC) lipids in high-voltage rectangular electrical Ðeld pulses, demonstrates that the major part of the turbidity and absorbance dichroism is caused by vesicle elongation under electric Maxwell stress. The kinetics of this electrochemomechanical shape deformation (time constants 0.1 O q/ls O 3) is determined both by the entrance of water and ions into the bulk membrane phase to form local electropores, and by the faster processes of membrane stretching and smoothing of thermal undulations. Moreover, the absorbance dichroism indicates local displacements of the chromophore relative to the membrane normal in the Ðeld. The slightly slower relaxations of the chemical turbidity and absorbance modes are both associated with the entrance of (*T `/T 0 ) ( *A`/A 0 ) solvent into the interface membrane/medium, caused by the alignment of the dipolar lipid head groups in one of the leaÑets at the pole caps of the vesicle bilayer. In addition, indicates changes in vesicle shape and volume. The results for lipid vesicles (*T `/T 0 ) provide guidelines for the analysis of electroporative deformations of biological cells.

Effect of Low-Intensity Pulsed Electric Fields on the Respiratory Activity and Electrosurface Properties of Bacteria

“…The PEFs used in the technological processes for the inactivation of microorganisms in natural liquid media such as milk and fruit juices have, as a rule, a high strength up to 40-50 kV cm −1 . [7][8][9][10] The pulsed electric fields are widely used for the introduction of a genetic material and drugs into eukaryotic and prokaryotic cells (electroporation) 11,12 and also for the creation of hybrid cells (electrofusion). 13 Ordinary values of the electric fields applied are ∼15 kV.…”

Giant vesicles in electric fields

“…The frequency dependence of vesicle deformation has been studied in detail, 36,[39][40][41]44,45 but the influence of solution conductivities has not been well explored. Note that in contrast to cells, one may vary both the external and the internal conductivity for vesicles.…”

“…13,14 A few other experiments have been performed but mainly with small vesicles, which are hundreds of nanometres in size. 45,51,52 Poration of small vesicles induced by DC pulses has attracted stronger interest. [52][53][54][55] Because of the small size of the vesicles, direct observation of the deformation and poration is not feasible.…”

Nonthermal irreversible electroporation for intracranial surgical applications

“…10 The exact mechanism of electroporation is unknown. Measurements of changes in membrane electrical properties 25,27 and species transport across cellular membranes 37,38 reveal that electroporation allows otherwise impermeant molecules to diffuse more freely through membranes. Although the precise mechanism by which electrical pulses permeabilize membranes is not known, it is believed that the potential induced across the membrane leads to instability in the lipid bilayer, resulting in a localized alteration of membrane shape into aqueous pores through which molecules can pass.…”