Altering dielectric properties of human cancer cells by varying electrical pulse durations

Summary form only given. Microsecond-duration pulsed electric fields (PEFs) above a certain voltage cause electroporation, or increased permeability of the cell membrane due to pore formation, while submicrosecond pulses induce intracellular effects. Models developed to describe and interpret these effects often depend on the electrical properties of the cells, which are altered by the PEF. We determined the complex permittivity of a cell suspension using time domain dielectric spectroscopy (TDDS). We used a two-shell model of the cell to calculate the conductivity and permittivity of the cell membrane, cytoplasm, nuclear envelope, and nucleoplasm from the complex permittivity. For long pulses (50 /spl mu/s), we found that cell membrane poration occurred within 10 s of the pulse, whereas poration was delayed by minutes for 10 ns pulses. These results indicate that membrane opening is the primary result for long pulses and a secondary result for ultrashort pulses, in agreement with other observations. Membrane recovery time is similar for both pulse durations. Our initial studies have focused on temporal changes in the cell membrane. TDDS will allow us to explore electrical pulse effects on the cell nucleus.