Methods of enhancing membrane permeabilization in a cell are provided. A method includes disposing the cell between a first electrode and a second electrode and applying a plurality of electrical pulses between the first electrode and the second electrode. In the method, the plurality of electrical pulses include at least two trains of pulses separated by an interval greater than about 10 s. Further, the amplitude of the electrical pulses is selected to be greater than about 0.2 kV/cm.