Molecular dynamics study of phospholipid membrane electroporation induced by bipolar pulses with different intervals

In this study, PM-EP induced by bipolar pulses with different intervals was investigated by all-atom molecular dynamics simulation. Firstly, PM-EP was formed during the positive pulse of 2ns and 0.5V/nm, then the effects of various intervals of 0, 1, 5, 10ns on PM-EP evolution were investigated, and the dynamic changes of different degrees of PM-EP induced by following negative pulses of 2ns and 0.5V/nm were analyzed. The elimination of the PM-EP during the interval of bipolar pulses were determined and it was related to the degrees of PM-EP and the time of intervals, then the degrees of PM-EP at the end of the intervals were classified and quantitatively defined, namely, Resealing, Destabilizing and Retaining state. These three states appeared due to the combined effect of both the preceding positive pulse and the interval. Furthermore, the evolution of PM-EP in resealing state under negative pulses was similar to that of positive pulses as evidenced by EP formation time and degree of PM-EP, the destabilizing state had the same trends as the resealing state except that the re-electroporation of phospholipid membrane appeared faster and larger degree of EP obtained with the same pulse exposure time. Regarding the retaining state, the negative pulses enhanced PM-EP with more profound water bridges, which can be considered as the effect of electric field superposition. These results can improve our understanding of the fundamental mechanism of bipolar pulse-induced PM-EP. Graphical Abstract Highlights Quantitative and qualitative definition of the three states of the phospholipid membrane electroporation at the end of the intervals. Clarification that the states of phospholipid membrane electroporation were generated due to the combined effect of positive pulses and intervals. Quantitative and qualitative comparison the evolution of the states of phospholipid membrane electroporation during the negative pulses.