## 1 Introduction  
Electroporation is a method in which short, direct high current square wave pulses induce transient permeation of cell membranes. Permeability is induced when the applied electric field leads to an increase in the transmembrane potential above the permeability threshold, leading to the formation of aqueous pores. With a high electric energy, the pores cannot be sealed, and cells undergo apoptosis, which is called irreversible electroporation (IRE). In addition, pores enable the delivery of foreign substances into cells [1; 2; 3]. Anticancer drugs and calcium have recently been used to increase the selectivity and efficiency of irreversible electroporation in tumor tissues [4; 5; 6]. These attempts have attracted attention due to fewer side effects and low cost compared to those of radiative cancer therapies.  
However, as IRE uses a high voltage in tissues, it has limitations regarding its clinical applications. Ablation of the IRE often has three regions due to the electric field distribution: the irreversible electroporation region, the reversible electroporation region, and the intact region. This results in incomplete resection of large tumors that are over 3 cm in diameter [7]. To overcome these disadvantages, a quite high voltage should be introduced, which cannot avoid electrolysis at the electrodes and sometimes causes muscle contraction [8; 9]. To address such limitations, some studies have explored more efficient ways to lower the required electric field strength. Dispersion of the ionic material around the target enhances electroporation. [PERSON] et al. showed that cationic peptides surrounding electroporated tissue can reduce the required applied electric field strength [10]. [PERSON] et al. showed that adding ionomycin to cells yields a higher probability of electroporation, as ionomycin induces hyperpolarization of the cell before electroporation [10; 11]. These chemicals used in electroporation are difficult to diffuse widely due to collagen fibers, and they can cause unexpected side effects.  
In contrast, unlike chemicals, light as an electromagnetic wave propagates relatively uniformly toward deep tissues. Light-tissue interactions include reflection and refraction, absorption of photon energy, and multiple scattering of photons when light encounters different tissue types. Absorption and multiple scattering of photons cause the light beam to broaden and attenuate as it passes through the tissue. In particular, near infrared (NIR) propagates into deeper tissues because it is less scattered and less absorbed by water molecules. The NIR-tissue interaction induces a transient temperature increase and triggers the activation of a transmembrane ion channel, which could initiate the generation of an action potential [12; 13]. The ability to change the cellular electrical properties suggests that NIR may affect cellular responses to IRE.  
In this study, we aimed to enhance the efficiency of IRE by using NIR irradiation. As we observed light-induced membrane potential changes from 810 nm NIR in previous studies, we utilized 810 nm NIR light to the human cervical cancer cell line, HeLa [14; 15]. HeLa cells are one of the most widely used cells for cancer research. Given that NIR effects have been reported to be dose dependent, we examined the cellular transmembrane potential and cellular reactive oxygen species (ROS) levels under different irradiation conditions [14]. We chose a NIR irradiation condition that induced hyperpolarization in the trans-membrane potential but reduced cytoplasmic ROS levels. Cellular viability was not affected by these irradiation conditions. Immediately after NIR irradiation, we applied high electric field pulses and analyzed membrane integrity and cell viability. We confirmed that pre-conditioning with 810 nm NIR irradiation of 3 \(\mathrm{J/cm^{2}}\) significantly enhanced IRE-induced apoptosis in HeLa cells. This result suggests the possibility of electrical modulation of cells by NIR and contributes to the clinical use of IRE at lower voltages.