Time-resolved measurement of the electric field induced by a plasma gun device in a conventional electroporation setup
Résumé
An organic tissue exposed to plasma experiences a highly reactive environment consisting of ions, electrons, free radicals, UV radiation, neutral molecules and electric field (EF). Of these active agents, EF is one of the least investigated up to these days [1]. Nevertheless, EF can potentially play a major role transiently increasing cell membrane permeability, a phenomenon commonly known as “electroporation” [2] and nowadays effectively used for several applications including gene transfection and electrochemotherapy [3]. Thus, in the present work, we report the time resolved measurement of the EF induced in a liquid medium within a typical electroporation setup by a plasma gun (PG) device. The results are compared with the values estimated for a conventional electroporation device (Cliniporator, IGEA SpA) in the perspective of a possible impact of plasma induced EF on biological targets. The comparison was done adopting a 4 well μ-slide (Ibidi®) armed with two plane parallel electrodes used for in-vitro electroporation test and filled with 500μl of the target liquid, being either SMEM culture medium or high purity water. Three different experimental cases were taken into account (Fig.1, left): 1) the plane electrodes powered by the Cliniporator; 2) the PG plume hitting on one plane electrode; 3) the PG plume hitting on the liquid with (3a) and without (3b) ground electrode. Despite the considerably higher voltage powering the plasma device, preliminary results show an EF on the target lower than the one applied by the electroporation system. This observation goes along with the recorded current that results in general one order of magnitude lower for the plasma system. Furthermore, results show a key role played by the grounding of the liquid medium which can hinder the induction of an EF by the plasma source. While still preliminary, presented results provide new insights on one of the less investigated aspects of plasma and liquid target interaction, the induced EF. Fig. 1: (left) Photos and schematics of the experimental set up; voltage, current and EF waveform for case 1 (center) and case 3b (right). This work and A.S. are supported by PLASCANCER project, INCa-PlanCancer-n°17CP087-00 References [1] E. Robert, T. Darny, S. Dozias, S. Iseni, J. M. Pouvesle, Physics of Plasma, 22, 122007 (2015). [2] D. Miklavćić; M. Puc, Wiley Encyclopedia of Biomedical Engineering, 1 (2006). [3] L. M. Mir, European J. of Cancer Supplement, 4, 38-44 (2006)