Digression on membrane electroporation for drug and gene delivery

Membrane electroporation (ME) defines an electrical technique to render lipid membranes porous and permeable, transiently and reversibly, by external voltage pulses. Although there are numerous applications of ME to manipulate cells, organelles and tissues in cell biology, biotechnology and medicine, yet the molecular mechanism of ME is only slowly being understood. A general chemical- thermodynamical approach for the quantitative description of cell membrane electroporation has been developed to provide the framework to quantitatively rationalize electroporative cell transformation and electroporative uptake of drug-like dyes into cells, as well as electrolyte efflux from salt-filled electroporated vesicles. Mechanistically, the electroporative transfer of gene and drug-like dyes involves the coupling between an interactive contact formation of the permeates with the cell surface membrane and the structural electroporation-resealing cycle C <--> (P) where C is the closed and (P) represents a number of different porated membrane states, respectively. The experimentally accessible concentration fraction f(p) = [(P)] / ([C] + [(P)]) of porous states is related to thermodynamic and electro-mechanic parameters such as temperature and the electric field strength, membrane rigidity or curvature. The results of the theoretical approach, mainly based on electrooptical data of lipid vesicles, have been successfully used to analyze single cells and to specify conditions for the practical purpose of direct electroporative gene transfer and drug delivery, in particular in the new medical disciplines of electroporative chemotherapy and electroporative gene vaccination.