Bioelectrics - Ultrashort High Voltage Pulses for Medical and Environmental Applications

Juergen F. Kolb

The application of pulsed electric fields with durations on the order of only nanoseconds and field strengths of several tens of kilovolts per centimeter has encouraged the development of novel medical therapies and environmental treatment possibilities. A straightforward application is the inactivation of microorganisms for water purification. However, arguably more interesting is the potential of pulsed electric fields to affect cell functions. Especially the induction of apoptotic cascades in cancer cells has brought the method to the attention of the medical community. In the meantime several studies in vivo could demonstrate that nanosecond pulsed electric field treatment is effective against melanoma tumors, pancreatic cancers and hepatocellular carcinomas. The technical challenge of the method is the application of short high voltage pulses across load-impedances that are on the order of a few Ohms. The much greater challenge is the diagnostic of the initial biophysical effects that are affecting cell functions and are eventually responsible for the biological response. The interaction of cells with electrics fields is determined by the dielectric characteristics of different cell types. To investigate respective parameters and changes induced by exposures, we used time domain dielectric spectroscopy together with fast imaging methods for the observation of changes in membrane potential and of other fast phenomena. The results allow us to draw conclusions on the fate of cells and treatments. To this end we have recently expanded basic studies that were so far mostly done on single cells towards tissue models and focused in particular on the communication between cells. In inactivation studies on bacteria we further found that the effect of pulsed electric fields can be enhanced when treatments are combined with exposures to non-thermal plasmas. This might open new venues for the related fields of Plasmamedicine and Bioelectrics.

Prof. Dr. Juergen F. Kolb received his doctorate degree in physics from the University of Erlangen-Nuremberg, Germany, in 1999. He was then a postdoctoral researcher at the Technical University of Darmstadt, Germany, and joined Old Dominion University, Norfolk VA in 2002. Here he was working on the pulsed breakdown of water and together with his colleagues on the development of the field of Bioelectrics. In 2011 he accepted a joint appointment as Leibniz Professor for Bioelectrics at the University of Rostock and the Leibniz Institute for Plasma Science and Technology Greifswald.