Browsing by Author "Kolb, Juergen F."
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- ItemAssessment of Phycocyanin Extraction from Cyanidium caldarium by Spark Discharges, Compared to Freeze-Thaw Cycles, Sonication, and Pulsed Electric Fields(Basel : MDPI, 2021) Sommer, Marie-Christine; Balazinski, Martina; Rataj, Raphael; Wenske, Sebastian; Kolb, Juergen F.; Zocher, KatjaPhycocyanin is a blue colored pigment, synthesized by several species of cyanobacteria and red algae. Besides the application as a food-colorant, the pigmented protein is of high interest as a pharmaceutically and nutritionally valuable compound. Since cyanobacteria-derived phycocyanin is thermolabile, red algae that are adapted to high temperatures are an interesting source for phycocyanin extraction. Still, the extraction of high quality phycocyanin from red algae is challenging due to the strong and rigid cell wall. Since standard techniques show low yields, alternative methods are needed. Recently, spark discharges have been shown to gently disintegrate microalgae and thereby enable the efficient extraction of susceptible proteins. In this study, the applicability of spark discharges for phycocyanin extraction from the red alga Cyanidium caldarium was investigated. The efficiency of 30 min spark discharges was compared with standard treatment protocols, such as three times repeated freeze-thaw cycles, sonication, and pulsed electric fields. Input energy for all physical methods were kept constant at 11,880 J to ensure comparability. The obtained extracts were evaluated by photometric and fluorescent spectroscopy. Highest extraction yields were achieved with sonication (53 mg/g dry weight (dw)) and disintegration by spark discharges (4 mg/g dw) while neither freeze-thawing nor pulsed electric field disintegration proved effective. The protein analysis via LC-MS of the former two extracts revealed a comparable composition of phycobiliproteins. Despite the lower total concentration of phycocyanin after application of spark discharges, the purity in the raw extract was higher in comparison to the extract attained by sonication.
- ItemCell stimulation versus cell death induced by sequential treatments with pulsed electric fields and cold atmospheric pressure plasma(San Francisco, California, US : PLOS, 2018) Steuer, Anna; Wolff, Christina M.; von Woedtke, Thomas; Weltmann, Klaus-Dieter; Kolb, Juergen F.Pulsed electric fields (PEFs) and cold atmospheric pressure plasma (CAP) are currently both investigated for medical applications. The exposure of cells to PEFs can induce the formation of pores in cell membranes and consequently facilitate the uptake of molecules. In contrast, CAP mainly acts through reactive species that are generated in the liquid environment. The objective of this study was to determine, if PEFs combined with plasma-treated cell culture medium can mutually reinforce effects on viability of mammalian cells. Experiments were conducted with rat liver epithelial WB-F344 cells and their tumorigenic counterpart WB-ras for a direct comparison of non-tumorigenic and tumorigenic cells from the same origin. Viability after treatments strongly depended on cell type and applied field strength. Notably, tumorigenic WB-ras cells responded more sensitive to the respective treatments than non-tumorigenic WB-F344 cells. More cells were killed when plasma-treated medium was applied first in combination with treatments with 100-μs PEFs. For the reversed treatment order, i.e. application of PEFs first, the combination with 100-ns PEFs resulted in a stimulating effect for non-tumorigenic but not for tumorigenic cells. The results suggest that other mechanisms, besides simple pore formation, contributed to the mutually reinforcing effects of the two methods.
- ItemCombination treatment with cold physical plasma and pulsed electric fields augments ros production and cytotoxicity in lymphoma(Basel : MDPI AG, 2020) Wolff, Christina M.; Kolb, Juergen F.; Weltmann, Klaus-Dieter; Woedtke, Thomas von; Bekeschus, SanderNew approaches in oncotherapy rely on the combination of different treatments to enhance the efficacy of established monotherapies. Pulsed electric fields (PEFs) are an established method (electrochemotherapy) for enhancing cellular drug uptake while cold physical plasma is an emerging and promising anticancer technology. This study aimed to combine both technologies to elucidate their cytotoxic potential as well as the underlying mechanisms of the effects observed. An electric field generator (0.9–1.0 kV/cm and 100-μs pulse duration) and an atmospheric pressure argon plasma jet were employed for the treatment of lymphoma cell lines as a model system. PEF but not plasma treatment induced cell membrane permeabilization. Additive cytotoxicity was observed for the metabolic activity and viability of the cells while the sequence of treatment in the combination played only a minor role. Intriguingly, a parallel combination was more effective compared to a 15-min pause between both treatment regimens. A combination effect was also found for lipid peroxidation; however, none could be observed in the cytosolic and mitochondrial reactive oxygen species (ROS) production. The supplementation with either antioxidant, a pan-caspase-inhibitor or a ferroptosis inhibitor, all partially rescued lymphoma cells from terminal cell death, which contributes to the mechanistic understanding of this combination treatment. © 2020 by the authors. Licensee MDPI, Basel, Switzerland.
- ItemCombined In Vitro Toxicity and Immunogenicity of Cold Plasma and Pulsed Electric Fields(Basel : MDPI, 2022) Wolff, Christina M.; Kolb, Juergen F.; Bekeschus, SanderIn modern oncology, therapies are based on combining monotherapies to overcome treatment resistance and increase therapy precision. The application of microsecond-pulsed electric fields (PEF) is approved to enhance local chemotherapeutic drug uptake within combination electrochemotherapy regimens. Reactive oxygen species (ROS) have been implicated in anticancer effects, and cold physical plasma produces vast amounts of ROS, which have recently been shown to benefit head and neck cancer patients. PEF and cold plasma technology have been linked to immunogenic cell death (ICD) induction, a regulated cell death accompanied by sterile inflammation that promotes antitumor immunity. To this end, we investigated the combined effect of both treatments regarding their intracellular ROS accumulation, toxicity, ICD-related marker expression, and optimal exposure sequence in a leukemia model cell line. The combination treatment substantially increased ROS and intracellular glutathione levels, leading to additive cytotoxic effects accompanied by a significantly increased expression of ICD markers, such as the eat-me signal calreticulin (CRT). Preconditioned treatment with cold plasma followed by PEF exposure was the most potent treatment sequence. The results indicate additive effects of cold plasma and PEF, motivating further studies in skin and breast tumor models for the future improvement of ECT in such patients.
- ItemComprehensive characterization of osseous tissues from impedance measurements by effective medium approximation(New York, NY : American Inst. of Physics, 2021) Wei, Wenzuo; Shi, Fukun; Zhuang, Jie; Kolb, Juergen F.A unified mixing (UM) model was developed to derive microstructural information of trabecular bone, i.e., bone volume fraction (BV/TV), from electrical impedance spectroscopy. A distinct advantage of the UM-model over traditional methods, such as equivalent circuit models and multivariate analysis, is that the influence of both the environment (hydroxyapatite) and different inclusions (water, fat, and air) can be taken into account simultaneously. In addition, interactions between the different components such as interfacial polarization can be addressed by a dedicated fitting parameter v. Accordingly, values of BV/TV for different bone samples, e.g., including or not including water, were determined in the higher frequency range of 1-5 MHz. Results showed good agreement with experimental data obtained by micro-computer tomography. In particular, predictions for dielectric parameters that were derived for 3 and 4 MHz were found most promising for the assessment and distinction of osteopathic conditions and differences. This was shown by a clear differentiation of osseous tissues, e.g., the greater trochanter, femoral head, and femoral neck.
- ItemCylindrospermopsin is effectively degraded in water by pulsed corona-like and dielectric barrier discharges(Amsterdam [u.a.] : Elsevier Science, 2020) Schneider, Marcel; Rataj, Raphael; Kolb, Juergen F.; Bláha, LuděkCylindrospermopsin (CYN) is an important cyanobacterial toxin posing a major threat to surface waters during cyanobacterial blooms. Hence, methods for cyanotoxin removal are required to confront seasonal or local incidences to sustain the safety of potable water reservoirs. Non-thermal plasmas provide the possibility for an environmentally benign treatment which can be adapted to specific concentrations and environmental conditions without the need of additional chemicals. We therefore investigated the potential of two different non-thermal plasma approaches for CYN degradation, operated either in a water mist, i.e. in air, or submerged in water. A degradation efficacy of 0.03 ± 0.00 g kWh−1 L−1 was found for a dielectric barrier discharge (DBD) operated in air, while a submerged pulsed corona-like discharge resulted in an efficacy of 0.24 ± 0.02 g kWh−1 L−1. CYN degradation followed a pseudo zeroth order or pseudo first order reaction kinetic, respectively. Treatment efficacy of the corona-like discharge submerged in water increased with pH values of the initial solution changing from 5.0 to 7.5. Notably, a pH-depending residual oxidative effect was observed for the submerged discharge, resulting in ongoing CYN degradation, even without further plasma treatment. In this case hydroxyl radicals were identified as the dominant oxidants of CYN at acidic pH values. In comparison, degradation by the DBD could be related primarily to the generation of ozone. © 2020 The AuthorsThe degradation of cylindrospermopsin by a pulsed corona-like discharge in water was more effective compared with a pulsed dielectric barrier discharge in air around a water mist. © 2020 The Authors
- ItemDegradation of glyphosate in water by the application of surface corona discharges(Bristol : IWA Publishing, 2021) Zocher, Katja; Gros, Peter; Werneburg, Matthias; Brüser, Volker; Kolb, Juergen F.; Leinweber, PeterGlyphosate (GLP) is one of the most widely applied herbicides, and is found ubiquitously in the environment. The removal of glyphosate from waste water and soil is challenging and can be achieved with chemical or biological methods, which, nevertheless, suffer from different disadvantages. The application of a physical plasma for the removal of GLP in water was examined by the application of surface corona discharges in a wire-to-cylinder setup filled with argon. The plasma was ignited at the liquid surface without any additives. By applying a photometric method, GLP was detected after derivatisation with fluorenyl methoxycarbonyl chloride, whereas phosphate was determined with ammonium molybdate. A GLP degradation rate of 90.8% could be achieved within a treatment time of 30 minutes with an estimated energy efficiency of 0.32 g/kWh.
- ItemDeposition of Antimicrobial Copper-Rich Coatings on Polymers by Atmospheric Pressure Jet Plasmas(Basel : MDPI, 2016) Kredl, Jana; Kolb, Juergen F.; Schnabel, Uta; Polak, Martin; Weltmann, Klaus-Dieter; Fricke, KatjaInanimate surfaces serve as a permanent reservoir for infectious microorganisms, which is a growing problem in areas in everyday life. Coating of surfaces with inorganic antimicrobials, such as copper, can contribute to reduce the adherence and growth of microorganisms. The use of a DC operated air plasma jet for the deposition of copper thin films on acrylonitrile butadiene styrene (ABS) substrates is reported. ABS is a widespread material used in consumer applications, including hospitals. The influence of gas flow rate and input current on thin film characteristics and its bactericidal effect have been studied. Results from X-ray photoelectron spectroscopy (XPS) and atomic force microscopy confirmed the presence of thin copper layers on plasma-exposed ABS and the formation of copper particles with a size in the range from 20 to 100 nm, respectively. The bactericidal properties of the copper-coated surfaces were tested against Staphylococcus aureus. A reduction in growth by 93% compared with the attachment of bacteria on untreated samples was observed for coverage of the surface with 7 at. % copper.
- ItemDiscrimination of different cell monolayers before and after exposure to nanosecond pulsed electric fields based on Cole-Cole and multivariate analysis(Bristol : IOP Publ., 2019) Shi, Fukun; Zhuang, Jie; Kolb, Juergen F.Normal and cancer cells, which were grown in monolayers, were investigated and discriminated by electrical bioimpedance spectroscopy (EBIS) before and after exposures to nanosecond pulsed electric fields (nsPEFs). Bioimpedance data were analysed with a Cole-Cole model and the principal component analysis (PCA). Normal and cancer cells could be clearly distinguished from each other either from Cole parameters (R 0, a, t) or from two dominant principal components. The trend of changes for Cole parameters indicated distinctively different post-nsPEF-effects between normal and cancer cells. PCA was also able to distinguish characteristic impedance spectra 30 min after exposures. The first principal component suggested that post-nsPEF-effects for normal cells were revealed especially at lower frequencies. The results indicated further that the extracellular resistance, which is dominated by cell-cell connections, might be an important factor with respect to selective nsPEF-effects on cancer cells that are organized in a monolayer or a tissue, respectively. Accordingly, the results support the application of EBIS as an early, non-invasive, label-free, and time-saving approach for the classification of cells to provide in particular predictive information on the success of cancer treatments with nsPEFs. © 2019 IOP Publishing Ltd.
- ItemHow activated carbon improves the performance of non-thermal plasma removing methyl ethyl ketone from a gas stream([Amsterdam] : Elsevier B.V., 2021) Schmidt, Michael; Kettlitz, Manfred; Kolb, Juergen F.The combination of non-thermal plasma (NTP), operated at room temperature and at atmospheric pressure in air and in combination with activated carbon filters offers a more efficient removal of VOCs from gas streams than each individual method alone. Efficiencies, synergies and mechanisms of this combination were investigated by means of comprehensive quantitative Fourier transform infrared spectroscopy analysis. Therefore, dry and wet synthetic air containing about 90 ppm of methyl ethyl ketone (MEK) were treated with non-thermal plasma (NTP) and an intentionally undersized activated carbon (AC) filter, separately and in combination. As a result, removal of about 50 % was achieved for NTP or AC alone but a removal close to 95 % was found for the combination. Ozone, generated by the NTP, was reduced by 55 % with the AC-filter. For the operation of the NTP with humid air, a decomposition of the pollutant on AC was observed even after the plasma was switched off.
- ItemHydrogen peroxide production of underwater nanosecond-pulsed streamer discharges with respect to pulse parameters and associated discharge characteristics(Bristol : IOP Publ., 2022) Rataj, Raphael; Werneburg, Matthias; Below, Harald; Kolb, Juergen F.Abstract Pulsed streamer discharges submerged in water have demonstrated potential in a number of applications. Especially the generation of discharges by short high-voltage pulses in the nanosecond range has been found to offer advantages with respect to efficacies and efficiencies. The exploited plasma chemistry generally relies on the initial production of short-lived species, e.g. hydroxyl radicals. Since the diagnostic of these transient species is not readily possible, a quantification of hydrogen peroxide provides an adequate assessment of underlying reactions. These conceivably depend on the characteristics of the high-voltage pulses, such as pulse duration, pulse amplitude, as well as pulse steepness. A novel electrochemical flow-injection system was used to relate these parameters to hydrogen peroxide concentrations. Accordingly, the accumulated hydrogen peroxide production for streamer discharges ignited in deionized water was investigated for pulse durations of 100 ns and 300 ns, pulse amplitudes between 54 kV and 64 kV, and pulse rise times from 16 ns to 31 ns. An independent control of the individual pulse parameters was enabled by providing the high-voltage pulses with a Blumlein line. Applied voltage, discharge current, optical light emission and time-integrated images were recorded for each individual discharge to determine dissipated energy, inception statistic, discharge expansion and the lifetime of a discharge. Pulse steepness did not affect the hydrogen peroxide production rate, but an increase in amplitude of 10 kV for 100 ns pulses nearly doubled the rate to (0.19 ± 0.01) mol l−1 s−1, which was overall the highest determined rate. The energy efficiency did not change with pulse amplitude, but was sensitive to pulse duration. Notably, production rate and efficiency doubled when the pulse duration decreased from 300 ns to 100 ns, resulting in the best peroxide production efficiency of (9.2 ± 0.9) g kWh−1. The detailed analysis revealed that the hydrogen peroxide production rate could be described by the energy dissipation in a representative single streamer. The production efficiency was affected by the corresponding discharge volume, which was comprised by the collective volume of all filaments. Hence, dissipating more energy in a filament resulted in an increased production rate, while increasing the relative volume of the discharge compared to its propagation time increased the energy efficiency.
- ItemImpedimetric Analysis of Trabecular Bone Based on Cole and Linear Discriminant Analysis(Lausanne : Frontiers Media, 2021) Wei, Wenzuo; Shi, Fukun; Kolb, Juergen F.A spatially unambiguous characterization of electrical properties of osseous tissues is important for the therapy of osteopathy via electrical stimulation. Accordingly, the study aimed to characterize the highly inhomogeneous composition and structures of different anatomical regions of trabecular bone based on their electrical properties. The electrical properties of 64 porcine trabecular bone samples were analyzed in a parallel plate electrode configuration and compared with published results. Therefore, a novel method, combining traditional Cole model with a linear discriminant analysis (LDA), was developed to discriminate the different regions, i.e., femur head, greater trochanter, and femur neck. Possible mechanisms behind the distinction for different regions could be interpreted from both methods. Respective adjacent regions with similar structure and composition could be distinguished from statistically significant differences of Cole parameters, i.e., α (p < 0.01) and R∞ (p < 0.05). The latter was correlated especially with water content, indicating an association of individual differences in microstructures in particular with conductivity. Conversely, different regions were unambiguously discriminated with LDA based on permittivity or conductivity. Contributions to the discrimination were explicitly reflected by the coefficients of the derived LDA features. A clear distinction was obtained especially for a frequency response at 950 kHz. Moreover, predictions for the classification of unspecified samples assigned them correctly to their origin with a success of 92.9%. The combination of both methods offers the possibility for a spatially resolved and eventually patient specific discrimination and evaluation of bone tissues and their response to therapies, notably electrical stimulation.
- ItemUncertainty Quantification and Sensitivity Analysis for the Electrical Impedance Spectroscopy of Changes to Intercellular Junctions Induced by Cold Atmospheric Plasma(Basel : MDPI, 2022) Zhuang, Jie; Zhu, Cheng; Han, Rui; Steuer, Anna; Kolb, Juergen F.; Shi, FukunThe influence of pertinent parameters of a Cole-Cole model in the impedimetric assessment of cell-monolayers was investigated with respect to the significance of their individual contribution. The analysis enables conclusions on characteristics, such as intercellular junctions. Especially cold atmospheric plasma (CAP) has been proven to influence intercellular junctions which may become a key factor in CAP-related biological effects. Therefore, the response of rat liver epithelial cells (WB-F344) and their malignant counterpart (WB-ras) was studied by electrical impedance spectroscopy (EIS). Cell monolayers before and after CAP treatment were analyzed. An uncertainty quantification (UQ) of Cole parameters revealed the frequency cut-off point between low and high frequency resistances. A sensitivity analysis (SA) showed that the Cole parameters, R0 and α were the most sensitive, while Rinf and τ were the least sensitive. The temporal development of major Cole parameters indicates that CAP induced reversible changes in intercellular junctions, but not significant changes in membrane permeability. Sustained changes of τ suggested that long-lived ROS, such as H2O2, might play an important role. The proposed analysis confirms that an inherent advantage of EIS is the real time observation for CAP-induced changes on intercellular junctions, with a label-free and in situ method manner.