Cell Fragmentation and Permeabilization by a 1 ns Pulse Driven Triple-Point Electrode

Abstract

Ultrashort electric pulses (ns-ps) are useful in gaining understanding as to how pulsed electric fields act upon biological cells, but the electric field intensity to induce biological responses is typically higher than longer pulses and therefore a high voltage ultrashort pulse generator is required. To deliver 1 ns pulses with sufficient electric field but at a relatively low voltage, we used a glass-encapsulated tungsten wire triple-point electrode (TPE) at the interface among glass, tungsten wire, and water when it is immersed in water. A high electric field (2 MV/cm) can be created when pulses are applied. However, such a high electric field was found to cause bubble emission and temperature rise in the water near the electrode. They can be attributed to Joule heating near the electrode. Adherent cells on a cover slip treated by the combination of these stimuli showed two major effects: (1) cells in a crater (<100 μm from electrode) were fragmented and the debris was blown away. The principal mechanism for the damage is presumed to be shear forces due to bubble collapse; and (2) cells in the periphery of the crater were permeabilized, which was due to the combination of bubble movement and microstreaming as well as pulsed electric fields. These results show that ultrashort electric fields assisted by microbubbles can cause significant cell response and therefore a triple-point electrode is a useful ablation tool for applications that require submillimeter precision.

Astrocyte Viability and Functionality in Spatially Confined Microcavitation Zone

“…These findings suggest that the astrocytes that were plated near the site of the collapse of microbubbles remained attached to the substrate but lost the cell functionality. These findings cannot be attributed to the primary shock waves but rather to the secondary pressure (55.8 ± 8.0 kPa) generated by the collapse of microbubbles that could have produced a short-lived shear stress or a microjet. , The four traces of intracellular calcium responses shown in Figure are meant to illustrate different calcium spiking profiles. Quantitative data analyses are provided below.…”

Diverse effects of pulsed electrical stimulation on cells - with a focus on chondrocytes and cartilage regeneration

“…PES has been reported to cause deleterious effects on cells, including cell death and cell fragmentation (Yang et al, 2018). PES with high field strength and long duration can result in thermal effects due to Joule heating (Yarmush et al, 2014), with consequent cell death, as proteins denature when the temperature reaches about 43-45 °C.…”