Figure 4. Theoretical analysis of DNA accumulation at the cell membrane due to electrophoretic force.

The number of DNA molecules (N_DNA) available for contact with the permeabilized part of the cell membrane for different plasmid c_DNA for plated cells (A) and cells in a suspension (B) are shown for HV and HV+LV pulses (corresponding transfection efficiencies are shown in Fig 1). The schematic representation shows the calculation of N_DNA, where L is the distance traveled due to electrophoresis and r_p is the radius of the permeabilized membrane (dotted, yellow area) for plated cells (A) and cells in a suspension (B). The gray shaded region represents the volume V from which DNA molecules are brought in contact with the cell membrane. The strength and length of pulses determine the distance L from which DNA can access the cell membrane (gray) and E determines the area of the membrane which is electropermeabilized.