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Katarína KUČEROVÁ, born Tarabová alumni student RG Scopus
PhD. study 2014 - 2021
Supervisor: Karol Hensel Consultant: -- Title: Cold plasma in a contact with liquid - Its chemical effects and selected biomedical and agriculture applications Abstract: The thesis deals with cold plasmas and plasma activated liquids and their applications in biomedicine and agriculture. Namely their use on various targets, such as biomolecules, bacteria, cells, seeds and plants. It consists of five scientific papers published in renowned journals preceded by a commentary including an introduction to all targets, associated plasma induced effects as reported in a literature, followed by our research objectives and a brief characteristic of achieved results. Various sources of cold plasmas of transient spark discharge, gliding arc discharge and He plasma jet are presented, and were used and operated in a contact with various water solutions. The plasma chemical effect and formation of gas phase species (NOX, N2O, HNO2, O3) and liquid phase species (•OH, H2O2, NO2‾, NO3‾) generated by these discharges were identified by absorption and fluorescence spectroscopy. The effect of various parameters, such as N2/O2 gas ratio or water activation time on reactive species formation and antibacterial efficiency of a model bacteria Escherichia coli are reported. Effects on bacterial inactivation by studied plasma sources was evaluated by standard plate count method. The strongest bactericidal effect was observed in non-buffered water solutions if discharge was generated in air-like mixture. The effect of the discharges on biomolecules, such as DNA or proteins as well as eukaryotic cells was also investigated. The results on HeLa and Vero mammalian cell viability, apoptosis and cell cycle indicate that cold plasma has a potential to selectively target cancerous cells. The effect of the plasma activated water on seed germination and plant growth stimulation was studied in in vitro and in vivo conditions. We observed improvement of wheat seed water uptake, germination, and early development of the seedlings. The increase of dry weight, photosynthetic pigments content, photosynthetic rate and suppress of antioxidant enzymes activity in wheat and lettuce plants were measured. The effect of plasma activated water was compared to H2O2 and/or NO3‾ solutions of various concentrations and were assessed their individual and combined role in the process of plants stimulation by the plasma activated water.
MSc. study 2012 - 2014
Supervisor: Karol Hensel Consultant: -- Title: Electrical discharge in contact with aqueous medium, their biological and chemical effects Abstract: We investigate chemical and biological effects of the transient spark discharge, generated by DC high voltage of positive polarity in atmospheric pressure air and applied to water solutions. We used water electrode system, where the liquid repetitively flow through the discharge zone. We analyzed changes induced by the discharge in two main solutions (sodium dihydrogen phosphate NaH2PO4 and saline solution NaCl) and their buffered counterparts (phosphate buffer and phosphate saline buffer). To explore biological effects of the discharge, Bacillus cereus, Escherichia coli and cancerous HeLa cells were used as model organisms. We monitored pH, conductivity and temperature of plasma treated solutions. We measured concentration of hydrogen peroxide H2O2 through its reaction with titanyl ions of titanium sulfate and formation of colored complex of pertitanic acid. By using indigo colorimetric method we evaluated the concentration of ozone O3 and by the colorimetric assay kit we measured the concentrations of nitrites NO2- and nitrates NO3-. Peroxynitrite ONOO concentration was determined by fluorescence probe DCF-DA. All the parameters were investigated in dependence on plasma treatment time. pH decrease, conductivity and temperature increase as well as the increase of concentration of all active species in time was observed. On the other hand, all these parameters were found independent of the flow rate of solution through the system. After the discharge we observed a decrease in concentrations of hydrogen peroxide, ozone, nitrites and the increase of nitrates. We refer to low selectivity of the indigo method toward ozone, and possibility of indigo solution being decolorized by hydroxyl radical, too. In the saline solution after 10 minutes of plasma treatment we achieved the decrease of bacterial population by 1.2 log reduction with B. cereus, 3 log reduction with E. coli and we inactivated 49 % of HeLa cells population. Finally, the effects induced by the transient spark in water electrode system were compared with the results achieved in the system of water electro-spray.
Bc. study 2011 - 2012
Supervisor: Karol Hensel Consultant: -- Title: Biodecontamination by pulsed electrical discharges Abstract: In the presented work we focus on biodecontamination by low-temperature nonequilibrium plasma produced by pulsed electric discharges in atmospheric pressure air. Pulsed discharges were generated by rotary spark gap high-voltage power supply. The objective was to examine the pulsed discharges and their use for bio-decontamination of gram-positive spore forming bacteria Bacillus cereus, evaluate their efficiency and dependence on various parameters (amplitude and frequency of applied voltage, exposure time) and compare it with the results obtained with direct current power supply. Two types of discharges were tested – spark discharge and corona discharge. The effect of the spark discharge was tested on bacteria in solution by utilizing electrostatic atomization, while spores deposited on the surfaces were subjected to the corona discharge. Bacterial samples were cultivated on Petri dishes and evaluated by plate count method. The results showed that the biocidal effect of pulsed spark discharge was lower compared with the effect of transient spark discharge generated by a direct current voltage. On the other hand, the efficiency of the corona discharge generated by pulsed power supply was found to be 20% higher than one obtained with direct current power, with negative polarity to be more efficicent than positive one. The results demonstrate the positive potential of the pulsed discharge toward the deconamination of bacteria. However, to unequivocally confirm our results and determine the relationship of the efficiency and the amplitude and frequency of the pulses and exposure time, further experiments are needed.
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Active
PhD students:
Jana KŠANOVÁ
Darina KUŽMOVÁ
Ramin MEHRABIFARD
Zuzana OKRUHLICOVÁ
Pankaj PAREEK
Gokul SELVARAJ
Sergei SMIRNOV
Peter TÓTH
MSc/Bc students:
Dominik DIŇA
Alumni
PhD students
MSc students
Bc students
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