Electroporation Based Drug Delivery and Its Applications

Abstract

When a certain strong electrical pulse applied across a cell or tissue, the structures of the cell or tissue would be rearranged to cause the permeabilization of the cell membrane, named in early 1980’s “electroporation”[1]. The theoretical and experimental studies of electric field effects on living cells with their bilayer lipid membrane has been studies in 1960’s to 1970’s century [1-6]. During these years, the researches were primarily dealt with reversible and irreversible membrane breakdown in vitro. Based on these research, the first gene transfer by custom-built electroporation chamber on murine cells was performed by Neumann et al. in 1982 [7]. When electric field (E≈0.2V, Usually 0.5-1V) applied across the cell membrane, a significant amount of electrical conductivity can increase on the cell plasma membrane. As a result, this electric field can create primary membrane “nanopores” with minimum 1 nm radius, which can transport small amount of ions such as Na+ and Clthrough this mem‐ brane “nanopores”. The essential features of electroporation included (a) short electric pulse application (b) lipid bilayer charging (c) structural rearrangements within the cell mem‐ brane (d) water-filled membrane structures, which can perforate the membrane (“aqueous pathways” or pores) and (e) increment of molecular and ionic transportation [8]. In conven‐ tional electroporation (Bulk electroporation) technique, an external high electric field pulses were applied to millions of cells in suspension together in-between two large electrodes. When this electric field was above the critical breakdown potential of the cell, a strong polarization of the cell membrane occur due to the high external electric field. Applying a very high electric field could be resulted in the formation of millions of pores into the cell membrane simultaneously without reversibility [9]. Several methods other than electropora‐ tion can be used for gene transfer like microprecipitates, microinjection, sonoporation,