brain barrier, this protocol could solve the problem of poor delivery of medications to the central nervous system, and potentially treat Alzheimer's disease, Parkinson's disease, and brain cancer, among other conditions. Bacterial transformation is generally the easiest way to make large amounts of a particular protein needed for biotechnology purposes or in medicine. Since gene electrotransfer is very simple, rapid and highly effective technique it first became very convenient replacement for other transformation procedures. Recent research has shown that shock waves could be used for pre-treating the cell membrane prior to electroporation. This synergistic strategy has shown to reduce external voltage requirement and create larger pores. Also application of shock waves allow scope to target desired membrane site. This procedure allows to control the size of the pore. Physical mechanism Electroporation allows cellular introduction of large highly charged molecules such as DNA which would never passively diffuse across the hydrophobic bilayer core. This phenomenon indicates that the mechanism is the creation of nm-scale water-filled holes in the membrane. Electropores were optically imaged in lipid bilayer models like droplet interface bilayers and giant unilamellar vesicles, while addition of cytoskeletal proteins such as actin networks to the giant unilamellar vesicles seem to prevent the formation of visible electropores. Experimental evidences for actin networks in regulating the cell membrane permeability has also emerged. Although electroporation and dielectric breakdown both result from application of an electric field, the mechanisms involved are fundamentally different. In dielectric breakdown the barrier material is ionized, creating a conductive pathway. The material alteration is thus chemical in nature. In contrast, during electroporation the lipid molecules are not chemically altered but simply shift position, opening up a pore which acts as the conductive pathway through the bilayer as it is filled with water. Electroporation is a dynamic phenomenon that depends on the local transmembrane voltage at each point on the cell membrane. It is generally accepted that for a given pulse duration and shape, a specific transmembrane voltage threshold exists for the manifestation of the electroporation phenomenon (from 0.5 V to 1 V). This leads to the definition of an electric field magnitude threshold for electroporation (Eth). That is, only the cells within areas where E≧Eth are electroporated. If a second threshold (Eir) is reached or surpassed, electroporation will compromise the viability of the cells, i.e., irreversible electroporation (IRE). Electroporation is a multi-step process with several distinct phases. First, a