Article 24

Dielectrophoresis; Electropermeabilization; Cell dielectrical properties; Single shell model; Crossover frequency

Dielectrophoresis was employed to distinguish the electroporated from non-electroporated cells. It was
found that the electric field frequency at which cells change the direction of their movement (the crossover frequency fCO) is higher when cells are electroporated. The contribution to the cell dielectrophoretic behavior of four electric and geometrical cell parameters was analyzed using a single shell model. fCO measurements were performed in media with conductivities of 0.001–0.09 S/m, on B16F10 cells which were electroporated in a Mannitol solution (0.001 S/m), using rectangular or exponential pulses. The control cells’ fCO was found in a domain of 2 to 105 kHz, while the electroporated cells’ fCO was in a domain of 5 to 350 kHz, depending on the external media conductivities. At exterior conductivities above ~0.02 S/m, fCO of electroporated cells
became significantly higher compared to controls. Even though the possible contribution of membrane permittivity to explain the observed fCO shift toward higher values cannot be excluded, the computations highlight the fact that the variation of cytosol conductivity might be the major contributor to the dielectrophoretic behavior change. Our experimental observations can be described by considering a linear dependence of electroporated cells’ cytosol conductivity against external conductivity.