To achieve high efficiency of electroporation and to minimize unwanted side effects, the electric field parameters must be optimized. Recently, it was suggested that biphasic high-frequency irreversible electroporation (H-FIRE) pulses reduce muscle contractions. However, it was also shown for sub-microsecond biphasic pulses that the opposite polarity phase of the pulse cancels the effect of the first phase if the interphase delay is short enough. We investigated the effect of interphase and interpulse delay (ranging from 0.5 to 10,000 µs) of 1 µs biphasic H-FIRE pulses on cell membrane permeabilization, on survival of four mammalian cell lines and determined metal release from aluminum, platinum and stainless steel electrodes. Biphasic H-FIRE pulses were compared to 8 × 100 µs monophasic pulses. We show that a longer interphase and interpulse delay results in lower cell survival, while the effects on cell membrane permeabilization are ambiguous. The cancellation effect was observed only for the survival of one cell line. Application of biphasic H-FIRE pulses results in lower metal release from electrodes but the interphase and interpulse delay does not have a large effect. The electrode material, however, importantly influences metal release - the lowest release was measured from platinum and the highest from aluminum electrodes.

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