Synergy of micro and nanosecond electrical pulses with chemotherapeutics on human cancer cell viability

Conventionally, microsecond electric pulses have been used for electroporation (μsEP) and electrochemotherapy (ECT). Recently, various studies have used nanosecond electric pulses (nsEP), which have different membrane effects. In addition to the differences in membrane effects, nanosecond pulses can directly manipulate intracellular organelles. Thus, it is of practical interest to study these two phenomena. In this study, changes in MDA-MB-231 human breast cancer cell viability were explored under both μsEP and nsEP, using 100 μs, 240 μs, and 60 ns, with electric field strengths of 1.2, 0.5, and 35 kV/cm, respectively. With curcumin, eight, 0.5 kV/cm, 240 μs pulses the viability was 42%, compared to 75% at eight 0.5 kV/cm, 240μs pulses alone. These had an energy equivalent of 480J/cm
³
. In comparison, at 580 J/cm
³
, the nsEP, with curcumin and eight 35 kV/cm, 60 ns, the viability was 70%, and it was only 71% at eight 35 kV/cm, 60 ns pulses alone. This indicates that for the same energy, μs pulses reduce the viability more with curcumin, than with pulses only. In nsEP, without curcumin, the viability was inversely proportional to pulse energy, as viability reduced 2.5× with 2.5× increase in pulse number from 8 to 20 at 35 kV/cm, 60 ns. These results might be helpful in selecting more appropriate parameters for μsEP and nsEP for clinical applications.