Frank Reidy Research Center for Bioelectrics, Old Dominion University, Norfolk, VA, USA.
Bioeffects Division, Airman System Directorate, 711th Human Performance Wing, Air Force Research Laboratory, JBSA Fort Sam Houston, TX, USA.
Bioelectrochemistry. 2023 Feb;149:108319. doi: 10.1016/j.bioelechem.2022.108319. Epub 2022 Nov 8.
The reversal of the electric field direction inhibits various biological effects of nanosecond electric pulses (nsEP). This feature, known as "bipolar cancellation," enables interference targeting of nsEP bioeffects remotely from stimulating electrodes, for prospective applications such as precise cancer ablation and non-invasive deep brain stimulation. This study was undertaken to achieve the maximum cancellation of electroporation, by quantifying the impact of the pulse shape, duration, number, and repetition rate across a broad range of electric field strengths. Monolayers of endothelial cells (BPAE) were electroporated in a non-uniform electric field. Cell membrane permeabilization was quantified by YO-PRO-1 (YP) dye uptake and correlated to local electric field strength. For most conditions tested, adding an opposite polarity phase reduced YP uptake by 50-80 %. The strongest cancellation, which reduced YP uptake by 95-97 %, was accomplished by adding a 50 % second phase to 600-ns pulses delivered at a high repetition rate of 833 kHz. Strobe photography of nanosecond kinetics of membrane potential in single CHO cells revealed the temporal summation of polarization by individual unipolar nsEP applied at sub-MHz rate, leading to enhanced electroporation. In contrast, there was no summation for bipolar pulses, and increasing their repetition rate suppressed electroporation. These new findings are discussed in the context of bipolar cancellation mechanisms and remote focusing applications.
电场方向的反转抑制了纳秒电脉冲（nsEP）的各种生物学效应。这种被称为“双极抵消”的特性，使 nsEP 生物效应能够在远离刺激电极的位置进行靶向干扰，有望应用于精确的癌症消融和非侵入性的深部脑刺激等领域。本研究旨在通过量化在广泛的电场强度范围内脉冲形状、持续时间、数量和重复率对电穿孔的影响，实现电穿孔的最大抵消。单层内皮细胞（BPAE）在非均匀电场中进行电穿孔。细胞膜通透性通过 YO-PRO-1（YP）染料摄取进行量化，并与局部电场强度相关联。对于大多数测试条件，添加相反极性的相位会将 YP 摄取减少 50-80%。通过在高重复率 833 kHz 下添加 50%的第二相位，对 600-ns 脉冲进行处理，可以达到最强的抵消效果，将 YP 摄取减少 95-97%。对单个 CHO 细胞膜电位纳秒动力学的频闪摄影显示，在亚 MHz 频率下应用单个单极 nsEP 会导致极化的时间总和，从而增强电穿孔。相比之下，双极脉冲没有总和，并且增加它们的重复率会抑制电穿孔。这些新发现将在双极抵消机制和远程聚焦应用的背景下进行讨论。
