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    ABSTRACT: Here, theoretical relationships between the parameters of the electric pulse, which is necessary to porate the cell by electric pulse of various shapes, have been obtained. The theoretical curves were compared with the experimental relationships. Experiments were carried out with human erythrocytes and mouse hepatoma MH-22A cells. The fraction of electroporated MH-22A cells was determined from the extent of the release of intracellular potassium ions and erythrocytes – from the extent of their hemolysis after long (20–24 h) incubation in 0.63% NaCl solution at 4 oC. The dependence of the fraction of electroporated cells on the amplitude of the electric field pulse was determined for pulses with the duration from 95 ns to 2 ms. The shapes of theoretical dependencies are in agreement with experimental ones. The cell poration time depended on the intensity of the pulse: the shorter the pulse duration, the higher the electric field strength has to be. This dependence is much more pronounced for pulses shorter than 1 μs. For example, if the pulse amplitude required to electroporate 50% of human erythrocytes increased from 1.0 to 1.76 kV/cm, when the duration of a square-wave pulse was reduced from 2 ms to 20 μs, it increased from 3 to 12 kV/cm, when the pulse duration was reduced from 950 to 95 ns. The relationships between the electric field strength required for electroporation and the frequency of the applied ac field were calculated for different pulse lengths. It has been obtained that although the electric field strength is constant for frequencies less than 10 kHz but its value depends on the pulse length decreasing with increasing pulse duration. At higher frequencies electric field strength is dependent on the frequency of the ac field.
    IEEE Transactions on Plasma Science 10/2013; 41(10):2913-2919. · 0.87 Impact Factor
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    ABSTRACT: This nanosecond electric pulse generator is designed for the electroporation of biological cells suspended in a liquid media. It is based on a spark-gap switch, which is optically triggered by a 0.45-ns duration and 1-mJ energy laser pulse (wavelength 1062 nm). This system can also be triggered manually by changing the distance between the spark-gap electrodes. It is able to generate in a 75-Oms impedance transmission line near-perfect square-shaped electric pulses (rise and fall times < 0.5 ns) with durations of 10, 40, 60, or 92 ns. The maximal amplitude of such pulses is 12.5 kV. The main advantage of this system is its ability to generate single pulses, the amplitude and duration of which can be precisely set in advance. To treat the cells, a coaxial cuvette with a 0.03-mL active volume and a 1-mm distance between the 28.3-mm^2 circular-shaped electrodes was used. The system was tested on human erythrocytes. It was demonstrated that for the 92- and 40-ns duration pulse, the amplitude required to electroporate 50% of the cells was 20 and 65 kV/cm, respectively.
    IEEE Transactions on Plasma Science 10/2013; 41(10):2706-2711. · 0.87 Impact Factor
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    ABSTRACT: Electroporation-based therapies are powerful biotechnological tools for enhancing the delivery of exogeneous agents or killing tissue with pulsed electric fields (PEFs). Electrochemotherapy (ECT) and gene therapy based on gene electrotransfer (EGT) both use reversible electroporation to deliver chemotherapeutics or plasmid DNA into cells, respectively. In both ECT and EGT, the goal is to permeabilize the cell membrane while maintaining high cell viability in order to facilitate drug or gene transport into the cell cytoplasm and induce a therapeutic response. Irreversible electroporation (IRE) results in cell kill due to exposure to PEFs without drugs and is under clinical evaluation for treating otherwise unresectable tumors. These PEF therapies rely mainly on the electric field distributions and do not require changes in tissue temperature for their effectiveness. However, in immediate vicinity of the electrodes the treatment may results in cell kill due to thermal damage because of the inhomogeneous electric field distribution and high current density during the electroporation-based therapies. Therefore, the main objective of this numerical study is to evaluate the influence of pulse number and electrical conductivity in the predicted cell kill zone due to irreversible electroporation and thermal damage. Specifically, we simulated a typical IRE protocol that employs ninety 100-µs PEFs. Our results confirm that it is possible to achieve predominant cell kill due to electroporation if the PEF parameters are chosen carefully. However, if either the pulse number and/or the tissue conductivity are too high, there is also potential to achieve cell kill due to thermal damage in the immediate vicinity of the electrodes. Therefore, it is critical for physicians to be mindful of placement of electrodes with respect to critical tissue structures and treatment parameters in order to maintain the non-thermal benefits of electroporation and prevent unnecessary damage to surrounding healthy tissue, critical vascular structures, and/or adjacent organs.
    PLoS ONE 01/2014; 9(8):e103083. · 3.53 Impact Factor

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