Jurij Novickij

Pulsed Electromagnetic Field Assisted in vitro Electroporation: A Pilot Study

Electroporation is a phenomenon occurring due to exposure of cells to Pulsed Electric Fields (PEF) which leads to increase of membrane permeability. Electroporation is used in medicine, biotechnology, and food processing. Recently, as an alternative to electroporation by PEF, Pulsed ElectroMagnetic Fields (PEMF) application causing similar biological effects was suggested. Since induced electric field in PEMF however is 2–3 magnitudes lower than in PEF electroporation, the membrane permeabilization mechanism remains hypothetical. We have designed pilot experiments where Saccharomyces cerevisiae and Candida lusitaniae cells were subjected to single 100–250 μs electrical pulse of 800 V with and without concomitant delivery of magnetic pulse (3, 6 and 9 T). As expected, after the PEF pulses only the number of Propidium Iodide (PI) fluorescent cells has increased, indicative of membrane permeabilization. We further show that single sub-millisecond magnetic field pulse did not cause detectable poration of yeast. Concomitant exposure of cells to pulsed electric (PEF) and magnetic field (PMF) however resulted in the increased number PI fluorescent cells and reduced viability. Our results show increased membrane permeability by PEF when combined with magnetic field pulse, which can explain electroporation at considerably lower electric field strengths induced by PEMF compared to classical electroporation.

High-frequency submicrosecond electroporator

ABSTRACT In this work, we present a novel electroporator which is capable of generating single and bursts of high power (3 kV, 60 A) square wave pulses of variable duration (100 ns to 1 ms) with predefined repetition frequency (1 Hz to 3.5 MHz). The proposed synchronized crowbar implementation ensures a constant pulse rise and fall times, which are independent from the load, thus highly relevant in electroporation. The electroporator was successfully tested for the inactivation of the human pathogen Candida albicans. The device is compatible with standard commercial electroporation cuvettes.

Manganite Sensor for Measurements of Magnetic Field Disturbances of Pulsed Actuators

Magnetic field sensors based on polycrystalline La0.83Sr0.17MnO3 films were used to measure the magnetic field distribution and disturbances during the operation of an electromagnetic launcher. Hollow cylinders made from dural aluminum and iron were used as propelled objects inside the solenoidal coil. The obtained results revealed the ability of manganite sensors to rapidly measure changing high magnetic fields of arbitrary waveforms.

Irreversible magnetoporation of micro-organisms in high pulsed magnetic fields.

Electroporation is an appealing way of stimulating living cells, which causes permanent or temporary nanoporosities in the structure of the biological objects. However, the technique has a disadvantage such as a requirement of contact between the electrodes and the cell medium. In this review, a methodology of contactless treatment of the biological objects using pulsed magnetic fields is proposed. The eukaryotic micro-organisms Achlya americana and Saprolegnia diclina have been used in the study and magnetic fields up to 7 T were applied, which caused effects similar to irreversible electroporation resulting in the death of the species. The proposed technique is applicable for different types of the biological cells or micro-organisms and possibly can be used in the area of cancer, antifungal treatment and other biotechnological fields.

Programmable Pulsed Magnetic Field System for Biological Applications

In this paper, a pulsed magnetic field system developed for biological applications is presented. The proposed pulsed power setup generates repetitive controlled frequency and width square wave 0-4 kV electrical pulses and supports currents up to 1000 A. As a load, a solenoid-type inductor is used with integrated plastic cuvette for biological cells. Homogeneous repetitive microsecond range pulsed magnetic field up to 15 T inside the effective volume of the cuvette can be generated. The development process, the structure of the pulsed magnetic field setup, and the solutions implemented to achieve biomedical applicability are overviewed in this paper. The presented experimental results showing contactless permeabilization of biological cells in pulsed magnetic field have an excellent potential for the development of a new biomedical treatment technique and applicability of the setup.

Microsecond pulsed magnetic field improves efficacy of antifungal agents on pathogenic microorganisms

Control and treatment of the emerging filamentous and yeast fungal diseases are of high priority in the biomedical field. This study investigated the influence of the pulsed magnetic field combined with common antifungal agents on the viability of various pathogenic fungi such as Aspergillus fumigatus, Candida albicans, and Trychophyton rubrum. Repetitive microsecond pulsed magnetic fields up to 6.1 T were applied in the study. The synergistic effect of co-applying drugs and magnetic treatment to different fungi species causing various human mycoses showed the potential for more effective and less toxic therapy.

Compact Electro-Permeabilization System for Controlled Treatment of Biological Cells and Cell Medium Conductivity Change Measurement

Abstract Subjection of biological cells to high intensity pulsed electric field results in the permeabilization of the cell membrane. Measurement of the electrical conductivity change allows an analysis of the dynamics of the process, determination of the permeabilization thresholds, and ion efflux influence. In this work a compact electro-permeabilization system for controlled treatment of biological cells is presented. The system is capable of delivering 5 μs - 5 ms repetitive square wave electric field pulses with amplitude up to 1 kV. Evaluation of the cell medium conductivity change is implemented in the setup, allowing indirect measurement of the ion concentration changes occurring due to the cell membrane permeabilization. The simulation model using SPICE and the experimental data of the proposed system are presented in this work. Experimental data with biological cells is also overviewed

High-Frequency CMR-B-Scalar Sensor for Pulsed Magnetic Field Measurement

To extend the frequency range of recently developed Colossal Magnetoresistance (CMR)-B-scalar sensors and to decrease the influence of induced picked-up (loop effect) voltages on the measured signal, a compensation method is used. A B-dot sensor of the same geometry as the CMR-B-scalar sensors current leads is used for this purpose. This allowed the subtraction of the time derivative of the magnetic field signal from the total measurement signal obtained by the CMR-B-scalar sensor. This B-dot sensor is placed at a distance of only 0.25 mm from the CMR-B-scalar sensor. The signal from the B-dot sensor is measured directly using an oscilloscope and subtracted from the signal of the CMR-B-scalar sensor with an empirically determined weight factor. This allowed the investigation of the high-frequency behavior of the CMR-B-scalar sensor using an oscillating source of a magnetic field with a time-derivative equal to 1.7 T/μs. Using the compensation method described above, it is possible to measure the magnetic field pulses with amplitudes up to 10 T and rise times down to 3.5 μs with an overall accuracy of ~10%.

High power facilities for electroporation of biological cells in pulsed magnetic fields

High power pulsed generator for non-contact cell electroporation application in pulsed magnetic fields is presented. Finite element method analysis of the magnetic field and the analysis of the Jurkat T lymphoblasts electroporation experimental data are overviewed. The dependence of cell electroporation efficiency on the structure of the microcoil was acquired experimentally. Possible problems of the technique, further developments and result overview are discussed.

AGEING EFFECTS ON ELECTRICAL RESISTIVITY AND MAGNETORESISTANCE OF NANOSTRUCTURED MANGANITE FILMS

The long-term stability of electrical resistance and magnetoresistance in nanostructured La1-xSrxMnO3 (x = 0.17) manganite thin films grown on lucalox (Al2O3 + MgO) substrate by the MOCVD method was investigated. It was found that the storage of up to 3 months of the free surfaces of these films in normal atmosphere (air) conditions increases their resistivity by almost two times, while the annealing of the films in an Ar atmosphere at 450 °C decreases their resistivity only by 15%. It was concluded that the final increase of resistivity is determined by a long-term relaxation of the grain boundaries in the nanostructured films. The magnetoresistance of the films does not change significantly, which produces an advantage for magnetic field sensor applications. The passive protective coating of the free surfaces of the films stabilizes their electrical and magnetic properties. The results were analysed using various electron scattering mechanisms when the films were in a ferromagnetic state, and the Mott’s variable range hopping model when they were in a paramagnetic insulating state.