Characterization of acoustic shockwaves generated by exposure to nanosecond electrical pulses

Abstract

Despite 30 years of research, the mechanism behind the induced breakdown of plasma membranes by electrical pulses, termed electroporation, remains unknown. Current theories treat the interaction between the electrical field and the membrane as an entirely electrical event pointing to multiple plausible mechanisms. By investigating the biophysical interaction between plasma membranes and nanosecond electrical pulses (nsEP), we may have identified a non-electric field driven mechanism, previously unstudied in nsEP, which could be responsible for nanoporation of plasma membranes. In this investigation, we use a non-contact optical technique, termed probe beam deflection technique (PBDT), to characterize acoustic shockwaves generated by nsEP traveling through tungsten wire electrodes. We conclude these acoustic shockwaves are the result of the nsEP exposure imparting electrohydraulic forces on the buffer solution. When these acoustic shockwaves occur in close proximity to lipid bilayer membranes, it is possible that they impart a sufficient amount of mechanical stress to cause poration of that membrane. This research establishes for the first time that nsEP discharged in an aqueous medium generate measureable pressure waves of a magnitude capable of mechanical deformation and possibly damage to plasma membranes. These findings provide a new insight into the longunanswered question of how electric fields cause the breakdown of plasma membranes.