@article{trosan_walther_mclaughlin_salvi_mazzeo_stapelmann_2023, title={Analysis of the effects of complex electrode geometries on the energy deposition and temporally and spatially & nbsp;averaged electric field measurements of surface dielectric barrier discharges}, volume={9}, ISSN={["1612-8869"]}, url={https://doi.org/10.1002/ppap.202300133}, DOI={10.1002/ppap.202300133}, abstractNote={Surface dielectric barrier discharges (SDBDs) have been gaining interest in part due to their scalability and flexibility of materials used, allowing larger electrodes with more complex geometries. This paper seeks to elucidate the properties of SDBD geometries utilizing differing repeated lattice structures. Voltage and current traces, optical emission spectroscopy, digital imaging, and numerical analysis are used to analyze the electrodes. Temporally and spatially averaged reduced electric fields and the total power deposited into the plasma are presented. The averaged reduced electric field is not significantly affected by increasing applied voltage, but minor variations could be observed due to the geometry of the electrode lattice structures. Finally, plasma power does not track linearly with perimeter in these more complicated lattice structures.}, journal={PLASMA PROCESSES AND POLYMERS}, author={Trosan, Duncan and Walther, Patrick and Mclaughlin, Stephen and Salvi, Deepti and Mazzeo, Aaron and Stapelmann, Katharina}, year={2023}, month={Sep} }
 @article{sponsel_gershman_stapelmann_2023, title={Electrical breakdown dynamics in an argon bubble submerged in conductive liquid for nanosecond pulsed discharges}, volume={56}, ISSN={["1361-6463"]}, url={https://doi.org/10.1088/1361-6463/acfb1b}, DOI={10.1088/1361-6463/acfb1b}, abstractNote={This study delves into the dynamics of cold atmospheric plasma and their interaction within conductive solutions under the unique conditions of nanosecond pulsed discharges (22 kV peak voltage, 10 ns FWHM, 4.5 kV ns−1 rate-of-rise). The research focuses on the electrical response, breakdown, and discharge propagation in an argon bubble, submerged in a NaCl solution of varying conductivity. Full or partial discharges were observed at conductivities of 1.5 µS cm−1 (deionized water) to 1.6 mS cm−1, but no breakdown was observed at 11.0 mS cm−1 when reducing the electrode gap. It is demonstrated that at higher conductivity electric breakdown is observed only when the gas bubble comes into direct contact with the electrode and multiple emission nodes were observed at different timescales. These nodes expanded in the central region of the bubble over timescales longer than the initial high-voltage pulse. This work offers a temporal resolution of 2 ns exposure times over the first 30 ns of the initial voltage pulse, and insight into plasma formation over decaying reflected voltage oscillations over 200 ns.}, number={50}, journal={JOURNAL OF PHYSICS D-APPLIED PHYSICS}, author={Sponsel, Nicholas L. and Gershman, Sophia and Stapelmann, Katharina}, year={2023}, month={Dec} }
 @misc{alves_becker_dijk_gans_go_stapelmann_tennyson_turner_kushner_2023, title={Foundations of plasma standards}, volume={32}, ISSN={["1361-6595"]}, url={https://doi.org/10.1088/1361-6595/acb810}, DOI={10.1088/1361-6595/acb810}, abstractNote={The field of low-temperature plasmas (LTPs) excels by virtue of its broad intellectual diversity, interdisciplinarity and range of applications. This great diversity also challenges researchers in communicating the outcomes of their investigations, as common practices and expectations for reporting vary widely in the many disciplines that either fall under the LTP umbrella or interact closely with LTP topics. These challenges encompass comparing measurements made in different laboratories, exchanging and sharing computer models, enabling reproducibility in experiments and computations using traceable and transparent methods and data, establishing metrics for reliability, and in translating fundamental findings to practice. In this paper, we address these challenges from the perspective of LTP standards for measurements, diagnostics, computations, reporting and plasma sources. This discussion on standards, or recommended best practices, and in some cases suggestions for standards or best practices, has the goal of improving communication, reproducibility and transparency within the LTP field and fields allied with LTPs. This discussion also acknowledges that standards and best practices, either recommended or at some point enforced, are ultimately a matter of judgment. These standards and recommended practices should not limit innovation nor prevent research breakthroughs from having real-time impact. Ultimately, the goal of our research community is to advance the entire LTP field and the many applications it touches through a shared set of expectations.}, number={2}, journal={PLASMA SOURCES SCIENCE & TECHNOLOGY}, author={Alves, Luis L. and Becker, Markus M. and Dijk, Jan and Gans, Timo and Go, David B. and Stapelmann, Katharina and Tennyson, Jonathan and Turner, Miles M. and Kushner, Mark J.}, year={2023}, month={Feb} }
 @article{morsell_trosan_stapelmann_shannon_2023, title={Plasma surface ionization wave interactions with single channels}, volume={32}, ISSN={["1361-6595"]}, url={https://doi.org/10.1088/1361-6595/acf9c9}, DOI={10.1088/1361-6595/acf9c9}, abstractNote={The study of plasma surface ionization waves (SIWs) in recent years has primarily focused on planar surfaces and periodic two dimensional structures. In application, substrates are likely to have non-planar morphology such as cracks, pores, and steps. Additionally, targets for the applications of medicine or catalysis may have targets with heterogeneous composition. This classification of targets are brought under the umbrella of complex interfaces. In this work, plasma SIWs were incident on a complex target consisting of a single channel cut into glass slides. The SIW velocities for the in-channel portion of the wave and radially propagating portion of the wave were tracked. It was found that surface wave velocities are not significantly affected by channel geometry, but primarily increase with pulse energy. A third propagation direction for the SIW is characterized in the azimuthal direction relative to the radial portion of the wave. Channel geometry is found to greatly effect the area treated by the plasma but not the propagation velocity of the surface wave. Surface wave morphology and the impact on application is also discussed. A simple model was introduced to understand the mechanisms behind SIW escape from a channel. It was found that the ratio of pulse energy to a geometry dependent minimum energy can predict the escape angle of a SIW from single channels.}, number={9}, journal={PLASMA SOURCES SCIENCE & TECHNOLOGY}, author={Morsell, Joshua and Trosan, Duncan and Stapelmann, Katharina and Shannon, Steven}, year={2023}, month={Sep} }
 @article{polito_quesada_stapelmann_kushner_2023, title={Reaction mechanism for atmospheric pressure plasma treatment of cysteine in solution}, volume={56}, ISSN={["1361-6463"]}, url={https://doi.org/10.1088/1361-6463/ace196}, DOI={10.1088/1361-6463/ace196}, abstractNote={Mechanisms for the cold atmospheric plasma (CAP) treatment of cells in solution are needed for more optimum design of plasma devices for wound healing, cancer treatment, and bacterial inactivation. However, the complexity of organic molecules on cell membranes makes understanding mechanisms that result in modifications (i.e. oxidation) of such compounds difficult. As a surrogate to these systems, a reaction mechanism for the oxidation of cysteine in CAP activated water was developed and implemented in a 0-dimensional (plug-flow) global plasma chemistry model with the capability of addressing plasma-liquid interactions. Reaction rate coefficients for organic reactions in water were estimated based on available data in the literature or by analogy to gas-phase reactions. The mechanism was validated by comparison to experimental mass-spectrometry data for COST-jets sustained in He/O2, He/H2O and He/N2/O2 mixtures treating cysteine in water. Results from the model were used to determine the consequences of changing COST-jet operating parameters, such as distance from the substrate and inlet gas composition, on cysteine oxidation product formation. Results indicate that operating parameters can be adjusted to select for desired cysteine oxidation products, including nitrosylated products.}, number={39}, journal={JOURNAL OF PHYSICS D-APPLIED PHYSICS}, author={Polito, Jordyn and Quesada, Maria J. Herrera and Stapelmann, Katharina and Kushner, Mark J.}, year={2023}, month={Sep} }
 @article{pillai_sponsel_stapelmann_bolotnov_2022, title={Direct Numerical Simulation of Bubble Formation Through a Submerged "Flute" With Experimental Validation}, volume={144}, ISSN={["1528-901X"]}, DOI={10.1115/1.4052051}, abstractNote={Abstract Direct numerical simulation (DNS) is often used to uncover and highlight physical phenomena that are not properly resolved using other computational fluid dynamics methods due to shortcuts taken in the latter to cheapen computational cost. In this work, we use DNS along with interface tracking to take an in-depth look at bubble formation, departure, and ascent through water. To form the bubbles, air is injected through a novel orifice geometry not unlike that of a flute submerged underwater, which introduces phenomena that are not typically brought to light in conventional orifice studies. For example, our single-phase simulations show a significant leaning effect, wherein pressure accumulating at the trailing nozzle edges leads to asymmetric discharge through the nozzle hole and an upward bias in the flow in the rest of the pipe. In our two-phase simulations, this effect is masked by the surface tension of the bubble sitting on the nozzle, but it can still be seen following departure events. After bubble departure, we observe the bubbles converge toward an ellipsoidal shape, which has been validated by experiments. As the bubbles rise, we note that local variations in the vertical velocity cause the bubble edges to flap slightly, oscillating between relatively low and high velocities at the edges.}, number={2}, journal={JOURNAL OF FLUIDS ENGINEERING-TRANSACTIONS OF THE ASME}, author={Pillai, Naveen and Sponsel, Nicholas L. and Stapelmann, Katharina and Bolotnov, Igor A.}, year={2022}, month={Feb} }
 @article{sponsel_gershman_quesada_mast_stapelmann_2022, title={Electric discharge initiation in water with gas bubbles: A time scale approach}, volume={40}, ISSN={["1520-8559"]}, url={https://doi.org/10.1116/6.0001990}, DOI={10.1116/6.0001990}, abstractNote={High voltage nanosecond pulse driven electric discharges in de-ionized water with an argon bubble suspended between two electrodes were experimentally investigated. Two electrode configurations were used to temporally resolve the time scales of the discharge from the applied voltage rise time (7 ns), through the end of the first pulse ([Formula: see text]30 ns), and longer (>50 ns). We found that, in positive and negative applied voltage polarities, discharge initiates in the water at the tip of the anode. The discharge in the water rapidly extends ([Formula: see text] m/s) to the apex of the bubble and light emitted from inside the bubble begins to form. The steep rate of rise of the applied voltage ([Formula: see text] kV/ns) and the short time for the development of discharge in the water suggest that cavitation is a likely mechanism for discharge initiation and propagation in water. In addition, the short duration of the applied voltage pulse results in only a partial Townsend discharge inside the bubble.}, number={6}, journal={JOURNAL OF VACUUM SCIENCE & TECHNOLOGY A}, author={Sponsel, Nicholas L. and Gershman, Sophia and Quesada, Maria J. Herrera J. and Mast, Jacob T. and Stapelmann, Katharina}, year={2022}, month={Dec} }
 @article{laroussi_bekeschus_keidar_bogaerts_fridman_lu_ostrikov_hori_stapelmann_miller_et al._2022, title={Low-Temperature Plasma for Biology, Hygiene, and Medicine: Perspective and Roadmap}, volume={6}, ISSN={["2469-7303"]}, url={https://doi.org/10.1109/TRPMS.2021.3135118}, DOI={10.1109/TRPMS.2021.3135118}, abstractNote={Plasma, the fourth and most pervasive state of matter in the visible universe, is a fascinating medium that is connected to the beginning of our universe itself. Man-made plasmas are at the core of many technological advances that include the fabrication of semiconductor devices, which enabled the modern computer and communication revolutions. The introduction of low temperature, atmospheric pressure plasmas to the biomedical field has ushered a new revolution in the healthcare arena that promises to introduce plasma-based therapies to combat some thorny and long-standing medical challenges. This article presents an overview of where research is at today and discusses innovative concepts and approaches to overcome present challenges and take the field to the next level. It is written by a team of experts who took an in-depth look at the various applications of plasma in hygiene, decontamination, and medicine, made critical analysis, and proposed ideas and concepts that should help the research community focus their efforts on clear and practical steps necessary to keep the field advancing for decades to come.}, number={2}, journal={IEEE TRANSACTIONS ON RADIATION AND PLASMA MEDICAL SCIENCES}, publisher={Institute of Electrical and Electronics Engineers (IEEE)}, author={Laroussi, Mounir and Bekeschus, Sander and Keidar, Michael and Bogaerts, Annemie and Fridman, Alexander and Lu, Xinpei and Ostrikov, Kostya and Hori, Masaru and Stapelmann, Katharina and Miller, Vandana and et al.}, year={2022}, month={Feb}, pages={127–157} }
 @article{pillai_sponsel_mast_kushner_bolotnov_stapelmann_2022, title={Plasma breakdown in bubbles passing between two pin electrodes}, volume={55}, ISSN={["1361-6463"]}, url={https://doi.org/10.1088/1361-6463/ac9538}, DOI={10.1088/1361-6463/ac9538}, abstractNote={The ignition of plasmas in liquids has applications from medical instrumentation to manipulation of liquid chemistry. Formation of plasmas directly in a liquid often requires prohibitively large voltages to initiate breakdown. Producing plasma streamers in bubbles submerged in a liquid with higher permittivity can significantly lower the voltage needed to initiate a discharge by reducing the electric field required to produce breakdown. The proximity of the bubble to the electrodes and the shape of the bubbles play critical roles in the manner in which the plasma is produced in, and propagates through, the bubble. In this paper, we discuss results from a three-dimensional direct numerical simulation (DNS) used to investigate the shapes of bubbles formed by injection of air into water. Comparisons are made to results from a companion experiment. A two-dimensional plasma hydrodynamics model was then used to capture the plasma streamer propagation in the bubble using a static bubble geometry generated by the DNS The simulations showed two different modes for streamer formation depending on the bubble shape. In an elliptical bubble, a short electron avalanche triggered a surface ionization wave (SIWs) resulting in plasma propagating along the surface of the bubble. In a circular bubble, an electron avalanche first traveled through the middle of the bubble before two SIWs began to propagate from the point closest to the grounded electrode where a volumetric streamer intersected the surface. In an elliptical bubble approaching a powered electrode in a pin-to-pin configuration, we experimentally observed streamer behavior that qualitatively corresponds with computational results. Optical emission captured over the lifetime of the streamer curve along the path of deformed bubbles, suggesting propagation of the streamer along the liquid/gas boundary interface. Plasma generation supported by the local field enhancement of the deformed bubble surface boundaries is a mechanism that is likely responsible for initiating streamer formation.}, number={47}, journal={JOURNAL OF PHYSICS D-APPLIED PHYSICS}, author={Pillai, Naveen and Sponsel, Nicholas L. and Mast, J. T. and Kushner, Mark J. and Bolotnov, Igor A. and Stapelmann, Katharina}, year={2022}, month={Nov} }
 @article{wapshott-stehli_myers_quesada_grunden_stapelmann_2022, title={Plasma-driven biocatalysis: In situ hydrogen peroxide production with an atmospheric pressure plasma jet increases the performance of OleT(JE) when compared to adding the same molar amount of hydrogen peroxide in bolus}, volume={2}, ISSN={["1612-8869"]}, url={https://doi.org/10.1002/ppap.202100160}, DOI={10.1002/ppap.202100160}, abstractNote={Abstract Enzymes like fatty acid peroxygenase OleT JE are desirable enzymes for the industry. While they require inexpensive hydrogen peroxide for activity, the same hydrogen peroxide also causes overoxidation of their reactive heme center. Here, we generate hydrogen peroxide slowly in situ using the Cooperation in Science and Technology (COST)‐Jet, an atmospheric pressure plasma jet, to avoid overoxidizing OleT JE . The COST‐Jet was operated in helium with a water admixture to provide hydrogen peroxide for OleT JE activity. This helium/water admixture produced the highest enzyme turnover numbers after 2 min of treatment. These turnover numbers were even superior to using an equimolar amount of hydrogen peroxide to treat the enzymes exogenously, showing that this plasma source can provide a reliable amount of reaction mediator to support OleT JE activity.}, journal={PLASMA PROCESSES AND POLYMERS}, author={Wapshott-Stehli, Hannah L. and Myers, Brayden G. and Quesada, Maria J. Herrera and Grunden, Amy and Stapelmann, Katharina}, year={2022}, month={Feb} }
 @article{myers_barnat_stapelmann_2021, title={Atomic oxygen density determination in the effluent of the COST reference source using in situ effective lifetime measurements in the presence of a liquid interface}, volume={54}, ISSN={["1361-6463"]}, url={https://doi.org/10.1088/1361-6463/ac1cb5}, DOI={10.1088/1361-6463/ac1cb5}, abstractNote={Spatially resolved, absolute densities of atomic oxygen are measured for several helium-based admixtures in the effluent of the COST Reference Microplasma Jet using two-photon absorption laser induced fluorescence (TALIF). Admixtures investigated include a helium-only admixture, four helium/oxygen admixtures (0.1 % , 0.5 % , 0.6 % , and 1.0 % oxygen), and a helium/water admixture (2500 ppm water), chosen to coincide with previously published characterizations of plasma-treated liquid. The atomic oxygen TALIF signal is calibrated for density using the noble gas xenon, which possesses a very similar two-photon excitation and fluorescence scheme. Measurements are conducted for the jet operating in ambient air with both an open effluent and a liquid surface present, allowing for comparison with liquid phase measurements conducted under similar conditions. The presence of a water surface does not appear to alter the background chemistry in the effluent but reduces O densities close to the liquid interface when compared to a similar distance from the nozzle in an open effluent case. This may be the result of a reduction in flow velocity caused by the liquid obstructing the gas flow. Additionally, measurements near the liquid surface revealed a region of atomic oxygen well outside of where the core of the effluent impinges on the liquid. This is likely relevant for applications as it considerably expands the surface area subject to O absorption. Critically, in situ measurements of the effective lifetimes of the laser-excited 3p3PJ state of atomic oxygen were recorded in the effluent by employing a picosecond (ps) laser and a nanosecond (ns) ICCD. By experimentally determining the contribution from collisional quenching via the in situ effective lifetime measurements, significant improvements in the accuracy of the atomic oxygen density calibration were made, with differences of approximately 30 % from existing methods of estimating quenching rates at atmospheric pressure. Finally, spatially resolved atomic oxygen densities allow for an investigation of O formation and extinction pathways in the effluent and a comparison between admixtures.}, number={45}, journal={JOURNAL OF PHYSICS D-APPLIED PHYSICS}, publisher={IOP Publishing}, author={Myers, Brayden and Barnat, Edward and Stapelmann, Katharina}, year={2021}, month={Nov} }
 @article{bhatt_brier‐jones_trosan_brinkley_pecoraro_smallwood_crofton_hudson_kirsch_stapelmann_et al._2021, title={Depyrogenation using plasmas: A novel approach for endotoxin deactivation using a dielectric barrier discharge at atmospheric pressure}, url={https://doi.org/10.1002/ppap.202100089}, DOI={10.1002/ppap.202100089}, abstractNote={Developing a low-cost depyrogenation process is vital in extending medical applicability of polymers that can be used in medicine. We present an overview of the plasma-based depyrogenation literature and address the need to develop a non-thermal plasma-based depyrogenation process for delicate materials such as chitosan. We present a low-cost plasma apparatus to treat chitosan powder in hermetically sealed bags. We decouple the experiments into two; depyrogenation experiments for dried standard endotoxin on glass slides, and chitosan modifications analysis through FTIR spectroscopy. We demonstrate depyrogenation efficacy with up to a 4-log reduction in endotoxin levels and discuss minor changes observed in plasma-treated chitosan.}, journal={Plasma Processes and Polymers}, author={Bhatt, Naman and Brier‐Jones, Justin and Trosan, Duncan and Brinkley, Cade and Pecoraro, Joshua and Smallwood, Jann and Crofton, Andrew and Hudson, Samuel and Kirsch, Wolff and Stapelmann, Katharina and et al.}, year={2021}, month={Nov} }
 @article{mohamed_gebski_reyes_beane_wigdahl_krebs_stapelmann_miller_2021, title={Differential Effect of Non-Thermal Plasma RONS on Two Human Leukemic Cell Populations}, volume={13}, ISSN={["2072-6694"]}, url={https://doi.org/10.3390/cancers13102437}, DOI={10.3390/cancers13102437}, abstractNote={Simple Summary As the number of investigations into the use of non-thermal plasma (NTP) for cancer treatment expands, it is becoming apparent that susceptibility of different cancer cells to NTP varies. We hypothesized that such differences could be attributed to the cell type-dependent interactions between NTP-generated reactive oxygen and nitrogen species (RONS) and the target cells. To test this hypothesis, we examined how two different human leukemic cell lines—Jurkat T lymphocytes and THP-1 monocytes—influence hydrogen peroxide and nitrite content in media after NTP exposure. We also assessed the potential of NTP to enhance immunogenicity in these cells and assayed phagocytosis of NTP-exposed leukemic cells by macrophages. Our results highlight the significance of target-mediated modulation of plasma chemical species in the development and clinical use of protocols involving plasma sources for use in cancer therapeutic application. Abstract Non-thermal plasma application to cancer cells is known to induce oxidative stress, cytotoxicity and indirect immunostimulatory effects on antigen presenting cells (APCs). The purpose of this study was to evaluate the responses of two leukemic cell lines—Jurkat T lymphocytes and THP-1 monocytes—to NTP-generated reactive oxygen and nitrogen species (RONS). Both cell types depleted hydrogen peroxide, but THP-1 cells neutralized it almost immediately. Jurkat cells transiently blunted the frequency-dependent increase in nitrite concentrations in contrast to THP-1 cells, which exhibited no immediate effect. A direct relationship between frequency-dependent cytotoxicity and mitochondrial superoxide was observed only in Jurkat cells. Jurkat cells were very responsive to NTP in their display of calreticulin and heat shock proteins 70 and 90. In contrast, THP-1 cells were minimally responsive or unresponsive. Despite no NTP-dependent decrease in cell surface display of CD47 in either cell line, both cell types induced migration of and phagocytosis by APCs. Our results demonstrate that cells modulate the RONS-mediated changes in liquid chemistry, and, importantly, the resultant immunomodulatory effects of NTP can be independent of NTP-induced cytotoxicity.}, number={10}, journal={CANCERS}, publisher={MDPI AG}, author={Mohamed, Hager and Gebski, Eric and Reyes, Rufranshell and Beane, Samuel and Wigdahl, Brian and Krebs, Fred C. and Stapelmann, Katharina and Miller, Vandana}, year={2021}, month={May} }
 @article{stapelmann_myers_quesada_lenker_ranieri_2021, title={Following O and OH in He/O-2 and He/H2O gas mixtures-from the gas phase through the liquid phase to modifications on a biological sample}, volume={54}, ISSN={["1361-6463"]}, url={https://doi.org/10.1088/1361-6463/ac18ec}, DOI={10.1088/1361-6463/ac18ec}, abstractNote={Applied cold atmospheric plasma allows for the controlled delivery of reactive oxygen and nitrogen species tailored for specific applications. Through the manipulation of the plasma parameters, feed gases, and careful consideration of the environment surrounding the treatment target, selective chemistries that preferentially influence the target can be produced and delivered. To demonstrate this, the COST reference microscale atmospheric pressure plasma jet is used to study the generation and transport of O and ⋅ OH from the gas phase through the liquid to the biological model target cysteine. Relative and absolute species densities of ⋅ OH and O are measured in the gas phase through laser induced fluorescence (LIF) and two-photon absorption LIF respectively. The transport of these species is followed into the liquid phase by hydrogen peroxide quantification and visualized by a fluorescence assay. Modifications to the model biological sample cysteine exposed to ⋅ OH and H2O2 dominated chemistry (He/H2O (0.25%)) and O dominated chemistry (He/O2 (0.6%)) is measured by FTIR spectroscopy. The origin of these species that modify cysteine is considered through the use of heavy water (H 218 O) and mass spectrometry. It is found that the reaction pathways differ significantly for He/O2 and He/H2O. Hydrogen peroxide is formed mainly in the liquid phase in the presence of a substrate for He/O2 whereas for He/H2O it forms in the gas phase. The liquid chemistry resulting from the He/O2 admixture mainly targets the sulfur moiety of cysteine for oxidation up to irreversible oxidation states, while He/H2O treatment leads preferentially to reversible oxidation products. The more O or OH/H2O2 dominated chemistry produced by the two gas admixtures studied offers the possibility to select species for target modification.}, number={43}, journal={JOURNAL OF PHYSICS D-APPLIED PHYSICS}, publisher={IOP Publishing}, author={Stapelmann, Katharina and Myers, Brayden and Quesada, Maria Herrera and Lenker, Eleanor and Ranieri, Pietro J.}, year={2021}, month={Oct} }
 @article{myers_ranieri_smirnova_hewitt_peterson_quesada_lenker_stapelmann_2021, title={Measuring plasma-generated center dot OH and O atoms in liquid using EPR spectroscopy and the non-selectivity of the HTA assay}, volume={54}, ISSN={["1361-6463"]}, url={https://doi.org/10.1088/1361-6463/abd9a6}, DOI={10.1088/1361-6463/abd9a6}, abstractNote={Plasma-generated hydroxyl radicals (·OH) and oxygen atoms (O) produced by the COST reference plasma jet, a micro-scaled atmospheric pressure plasma jet, were investigated using a variety of experimental techniques. Several gas admixtures were studied to distinguish the contributions of the two reactive oxygen species. Large discrepancies between inferred aqueous ·OH densities were noted when using a 2-hydroxyterephthalic acid (HTA) fluorescence assay and electron paramagnetic resonance (EPR) measurements with the spin trap 5,5-dimethyl-1-pyrroline N-oxide—especially when oxygen was present in the feed gas. A series of follow-up experiments including optical emission spectroscopy, H2O2 quantification, and EPR measurements of atomic oxygen using the spin trap 2,2,6,6-tetramethylpiperidine, revealed that the inconsistencies between the measured aqueous ·OH were likely due to the propensity of atomic oxygen to hydroxylate TA in a manner indistinguishable from ·OH. This renders the HTA assay non-selective when both ·OH radicals and atomic oxygen are present, which we report for all three gas admixtures in our experiments. Additionally, considerable degradation of both HTA and the spin adducts measured using EPR spectroscopy was apparent, meaning actual radical densities in the plasma-treated liquid may be considerably higher than implied. Degradation rates compared favorably to previously measured gas phase densities of atomic oxygen in the predecessor of the COST jet and reported degradation of other chemical probes. These results show the prolific role of atomic oxygen in plasma-induced liquid chemistry and caution against diagnostic techniques that are unable to account for it.}, number={14}, journal={JOURNAL OF PHYSICS D-APPLIED PHYSICS}, publisher={IOP Publishing}, author={Myers, B. and Ranieri, P. and Smirnova, T. and Hewitt, P. and Peterson, D. and Quesada, M. Herrera and Lenker, E. and Stapelmann, K.}, year={2021}, month={Apr} }
 @article{ranieri_sponsel_kizer_rojas‐pierce_hernández_gatiboni_grunden_stapelmann_2021, title={Plasma agriculture: Review from the perspective of the plant and its ecosystem}, url={https://doi.org/10.1002/ppap.202000162}, DOI={10.1002/ppap.202000162}, abstractNote={Abstract Plasma agriculture details the role of nonthermal plasma in the development of plants from seeds to crops. Several publications reported enhanced plant growth, improved stress tolerance, and antimicrobial effects of plasma treatment and plasma‐treated water. In this review, we present an overview of the recent plasma agriculture literature and put it in the context of the plant needs and the effects on the plant ecosystem. We will discuss key developmental stages of plants and their needs, the different growth environments from hydroponics to soilless and soil substrates, and the plant microbiome. This review provides the context to design plasma‐based fertilization strategies to address the needs of plants and their ecosystem.}, journal={Plasma Processes and Polymers}, author={Ranieri, Pietro and Sponsel, Nicholas and Kizer, Jon and Rojas‐Pierce, Marcela and Hernández, Ricardo and Gatiboni, Luciano and Grunden, Amy and Stapelmann, Katharina}, year={2021}, month={Jan} }
 @article{lin_stapelmann_bogaerts_2020, title={Advances in Plasma Oncology toward Clinical Translation}, url={https://doi.org/10.3390/cancers12113283}, DOI={10.3390/cancers12113283}, abstractNote={This Special Issue on "Advances in Plasma Oncology Toward Clinical Translation" aims to bring together cutting-edge research papers within the field in the context of clinical translation and application [...].}, journal={Cancers}, author={Lin, Abraham and Stapelmann, Katharina and Bogaerts, Annemie}, year={2020}, month={Nov} }
 @article{smilowicz_kogelheide_schone_stapelmann_awakowicz_metzler-nolte_2020, title={Catalytic oxidation of small organic molecules by cold plasma in solution in the presence of molecular iron complexes}, volume={10}, ISSN={["2045-2322"]}, DOI={10.1038/s41598-020-78683-7}, abstractNote={Abstract The plasma-mediated decomposition of volatile organic compounds has previously been investigated in the gas phase with metal oxides as heterogeneous catalysts. While the reactive species in plasma itself are well investigated, very little is known about the influence of metal catalysts in solution. Here, we present initial investigations on the time-dependent plasma-supported oxidation of benzyl alcohol, benzaldehyde and phenol in the presence of molecular iron complexes in solution . Products were identified by HPLC, ESI-MS, FT-IR, and $$^{1}\hbox {H NMR}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:msup> <mml:mrow /> <mml:mn>1</mml:mn> </mml:msup> <mml:mtext>H NMR</mml:mtext> </mml:mrow> </mml:math> spectroscopy. Compared to metal-free oxidation of the substrates, which is caused by reactive oxygen species and leads to a mixture of products, the metal-mediated reactions lead to one product cleanly, and faster than in the metal-free reactions. Most noteworthy, even catalytic amounts of metal complexes induce these clean transformations. The findings described here bear important implications for plasma-supported industrial waste transformations, as well as for plasma-mediated applications in biomedicine, given the fact that iron is the most abundant redox-active metal in the human body.}, number={1}, journal={SCIENTIFIC REPORTS}, author={Smilowicz, Dariusz and Kogelheide, Friederike and Schone, Anna Lena and Stapelmann, Katharina and Awakowicz, Peter and Metzler-Nolte, Nils}, year={2020}, month={Dec} }
 @article{kogelheide_offerhaus_bibinov_krajinski_schücke_schulze_stapelmann_awakowicz_2020, title={Characterisation of volume and surface dielectric barrier discharges in N2–O2 mixtures using optical emission spectroscopy}, url={https://doi.org/10.1002/ppap.201900126}, DOI={10.1002/ppap.201900126}, abstractNote={Abstract A volume and a twin surface dielectric barrier discharge (VDBD and SDBD) are generated in different nitrogen–oxygen mixtures at atmospheric pressure by applying damped sinusoidal voltage waveforms with oscillation periods in the microsecond time scale. Both electrode configurations are located inside vacuum vessels and operated in a controlled atmosphere to exclude the influence of surrounding air. The discharges are characterised with different spatial and temporal resolution by applying absolutely calibrated optical emission spectroscopy in conjunction with numerical simulations and current–voltage measurements. Plasma parameters, namely the electron density and the reduced electric field, and the dissipated power are found to depend strongly on the oxygen content in the working gas mixture. Different spatial and temporal distributions of plasma parameters and dissipated power are explained by surface and residual volume charges for different O 2 admixtures due to their effects on the electron recombination rate. Thus, the oxygen admixture is found to strongly influence the breakdown process and plasma conditions of a VDBD and a SDBD.}, journal={Plasma Processes and Polymers}, author={Kogelheide, Friederike and Offerhaus, Björn and Bibinov, Nikita and Krajinski, Philip and Schücke, Lars and Schulze, Julian and Stapelmann, Katharina and Awakowicz, Peter}, year={2020}, month={Jun} }
 @article{ranieri_mohamed_myers_dobossy_beyries_trosan_krebs_miller_stapelmann_2020, title={GSH Modification as a Marker for Plasma Source and Biological Response Comparison to Plasma Treatment}, volume={10}, url={https://doi.org/10.3390/app10062025}, DOI={10.3390/app10062025}, abstractNote={This study investigated the use of glutathione as a marker to establish a correlation between plasma parameters and the resultant liquid chemistry from two distinct sources to predefined biological outcomes. Two different plasma sources were operated at parameters that resulted in similar biological responses: cell viability, mitochondrial activity, and the cell surface display of calreticulin. Specific glutathione modifications appeared to be associated with biological responses elicited by plasma. These modifications were more pronounced with increased treatment time for the European Cooperation in Science and Technology Reference Microplasma Jet (COST-Jet) and increased frequency for the dielectric barrier discharge and were correlated with more potent biological responses. No correlations were found when cells or glutathione were exposed to exogenously added long-lived species alone. This implied that short-lived species and other plasma components were required for the induction of cellular responses, as well as glutathione modifications. These results showed that comparisons of medical plasma sources could not rely on measurements of long-lived chemical species; rather, modifications of biomolecules (such as glutathione) might be better predictors of cellular responses to plasma exposure.}, number={6}, journal={Applied Sciences}, publisher={MDPI AG}, author={Ranieri, Pietro and Mohamed, Hager and Myers, Brayden and Dobossy, Leah and Beyries, Keely and Trosan, Duncan and Krebs, Fred C. and Miller, Vandana and Stapelmann, Katharina}, year={2020}, month={Mar}, pages={2025} }
 @article{kogelheide_voigt_hillebrand_moeller_fuchs_gibson_awakowicz_stapelmann_fiebrandt_2020, title={The role of humidity and UV-C emission in the inactivation of B. subtilis spores during atmospheric-pressure dielectric barrier discharge treatment}, volume={53}, url={https://doi.org/10.1088/1361-6463/ab77cc}, DOI={10.1088/1361-6463/ab77cc}, abstractNote={Experiments are performed to assess the inactivation of Bacillus subtilis spores using a non-thermal atmospheric-pressure dielectric barrier discharge. The plasma source used in this study is mounted inside a vacuum vessel and operated in controlled gas mixtures. In this context, spore inactivation is measured under varying nitrogen/oxygen and humidity content and compared to spore inactivation using ambient air. Operating the dielectric barrier discharge in a sealed vessel offers the ability to distinguish between possible spore inactivation mechanisms since different process gas mixtures lead to the formation of distinct reactive species. The UV irradiance and the ozone density within the plasma volume are determined applying spectroscopic diagnostics with neither found to fully correlate with spore inactivation. It is found that spore inactivation is most strongly correlated with the humidity content in the feed gas, implying that reactive species formed, either directly or indirectly, from water molecules are strong mediators of spore inactivation.}, number={29}, journal={Journal of Physics D: Applied Physics}, publisher={IOP Publishing}, author={Kogelheide, Friederike and Voigt, Farina and Hillebrand, Bastian and Moeller, Ralf and Fuchs, Felix and Gibson, Andrew R. and Awakowicz, Peter and Stapelmann, Katharina and Fiebrandt, Marcel}, year={2020}, month={Jul}, pages={295201} }
 @article{balzer_demir_kogelheide_fuchs_stapelmann_oplaender_2019, title={Cold atmospheric plasma (CAP) differently affects migration and differentiation of keratinocytes via hydrogen peroxide and nitric oxide-related products}, volume={13}, ISSN={["2212-8166"]}, url={https://doi.org/10.1016/j.cpme.2018.11.001}, DOI={10.1016/j.cpme.2018.11.001}, abstractNote={A promising approach to treat infected chronic wounds is the treatment with “cold” atmospheric plasma (CAP) that has a broad antibacterial spectrum and can enhance microcirculation. Dielectric barrier discharge (DBD) devices generate CAP containing reactive species, leading to acidification and the accumulation of hydrogen peroxide (H2O2), nitrite and nitrate within the treated tissue/liquids. Since CAP produced species may affect wound healing and cell behavior, we investigated the possible DBD/CAP-induced effects on human keratinocytes. Primary keratinocytes were treated by a DBD device (13.5 kV, 300 Hz; 0–300 s). DBD-induced changes (pH; nitrite, nitrate; H2O2) in treated media were evaluated. As control and to investigate the impact of the CAP-produced species, equivalents amounts of H2O2, HCL, nitrite and nitrate as obtained by CAP treatments (0, 60, 300 s) were added separately or combined to keratinocytes. Cell viability and proliferation were determined by live cell imaging and a resazurin-based assay. Gap closure rates were assessed by migration assays. Differentiation/proliferation states were determined by qRT-PCR analysis of KI67 and involucrin. We found that even longer CAP-treatment times (300 s) did not reduce cell viability. However, migration/proliferation was affected by longer treatments resulting in a delay of gap closure in migration assays. The mRNA expression of involucrin and KI67 showed a pro-differentiation effect induced by longer CAP treatment. Similar effects could be induced by adding H2O2 in amounts found after a 300 s CAP treatment. The effects were reversed by catalase. Shorter CAP treatment (60 s) did not reveal pro-differentiation effects, but significantly accelerated gap closure. Lower H2O2 concentrations, equivalent to a 60 s CAP treatment, induced also upregulation of involucrin, which in turn could be diminished by low concentrations of nitrite/nitrate, indicating a potential mediation of H2O2-induced effects by parallel CAP-induced accumulation of these nitric oxide derivatives. CAP treatment theoretically could kill several birds with one stone—overcome bacterial contamination, improve microcirculation and additionally compensate missing H2O2 and nitric oxide— facilitating wound healing. However, clinical CAP treatment must be well balanced to avoid possible unwanted side effects, such as a delayed healing process and tissue damage.}, journal={CLINICAL PLASMA MEDICINE}, publisher={Elsevier BV}, author={Balzer, Julian and Demir, Erhan and Kogelheide, Friederike and Fuchs, Paul C. and Stapelmann, Katharina and Oplaender, Christian}, year={2019}, month={Mar}, pages={1–8} }
 @article{offerhaus_kogelheide_jalat_bibinov_schulze_stapelmann_awakowicz_2019, title={Determination of NO densities in a surface dielectric barrier discharge using optical emission spectroscopy}, url={https://doi.org/10.1063/1.5094894}, DOI={10.1063/1.5094894}, abstractNote={A new computationally assisted diagnostic to measure NO densities in atmospheric-pressure microplasmas by Optical Emission Spectroscopy (OES) is developed and validated against absorption spectroscopy in a volume Dielectric Barrier Discharge (DBD). The OES method is then applied to a twin surface DBD operated in N 2 to measure the NO density as a function of the O 2 admixture ( 0.1%– 1%). The underlying rate equation model reveals that NO ( A 2 Σ + ) is primarily excited by reactions of the ground state NO ( X 2 Π ) with metastables N 2 ( A 3 Σ u + ).A new computationally assisted diagnostic to measure NO densities in atmospheric-pressure microplasmas by Optical Emission Spectroscopy (OES) is developed and validated against absorption spectroscopy in a volume Dielectric Barrier Discharge (DBD). The OES method is then applied to a twin surface DBD operated in N 2 to measure the NO density as a function of the O 2 admixture ( 0.1%– 1%). The underlying rate equation model reveals that NO ( A 2 Σ + ) is primarily excited by reactions of the ground state NO ( X 2 Π ) with metastables N 2 ( A 3 Σ u + ).}, journal={Journal of Applied Physics}, author={Offerhaus, B. and Kogelheide, F. and Jalat, D. and Bibinov, N. and Schulze, J. and Stapelmann, K. and Awakowicz, P.}, year={2019}, month={Nov} }
 @article{naumova_engel_kranz_schneider_tietze_dittmar_fiebrandt_stapelmann_piwowarczyk_kuczius_et al._2019, title={Low-Pressure Plasma Sterilization for Test Specimens to be Worn on Splints in the Oral Cavity}, volume={9}, ISSN={["2079-6412"]}, DOI={10.3390/coatings9020099}, abstractNote={Bacterial biofilms adhere to all oral surfaces and may alter or degrade them. For investigations of the oral biofilm, growing on new restorative dental biomaterials, sterilized dental enamel surfaces as natural, control, and reference materials are used. A novel method for disinfection and sterilization of surfaces is low-pressure plasma (LPP) sterilization, which is a nondestructive and nontoxic technology. The roughness of the dental enamel surface was determined before and after LPP sterilization. Enamel discs were placed in dental splints and worn for five days in vivo. Oral biofilm was fixed for scanning electron microscopy (SEM). Biofilms growing in vitro were characterized microbiologically before and after sterilization and examined by confocal laser scanning microscopy (CLSM). Microbiology demonstrated that various bacterial strains were present in the biofilms. SEM showed multiple layers of densely packed bacteria, and CLSM demonstrated that the biofilm contained live and dead bacteria. After LPP sterilization, no biofilm could be detected, and the enamel surface remained unaltered. It may be concluded that LPP sterilization is an effective, nondestructive method for disinfection of enamel before application in the oral cavity. LPP sterilization may be suitable for sterilization of dental materials without altering their surfaces.}, number={2}, journal={COATINGS}, author={Naumova, Ella A. and Engel, Alexander-Simon and Kranz, Hagen Tizian and Schneider, Marvin and Tietze, Jan and Dittmar, Thomas and Fiebrandt, Marcel and Stapelmann, Katharina and Piwowarczyk, Andree and Kuczius, Thorsten and et al.}, year={2019}, month={Feb} }
 @article{lackmann_bruno_jablonowski_kogelheide_offerhaus_held_gathen_stapelmann_woedtke_wende_2019, title={Nitrosylation vs. oxidation – How to modulate cold physical plasmas for biological applications}, volume={14}, url={https://doi.org/10.1371/journal.pone.0216606}, DOI={10.1371/journal.pone.0216606}, abstractNote={Thiol moieties are major targets for cold plasma-derived nitrogen and oxygen species, making CAPs convenient tools to modulate redox-signaling pathways in cells and tissues. The underlying biochemical pathways are currently under investigation but especially the role of CAP derived RNS is barely understood. Their potential role in protein thiol nitrosylation would be relevant in inflammatory processes such as wound healing and improving their specific production by CAP would allow for enhanced treatment options beyond the current application. The impact of a modified kINPen 09 argon plasma jet with nitrogen shielding on cysteine as a thiol-carrying model substance was investigated by FTIR spectroscopy and high-resolution mass spectrometry. The deposition of short-lived radical species was measured by electron paramagnetic resonance spectroscopy, long-lived species were quantified by ion chromatography (NO2-, NO3-) and xylenol orange assay (H2O2). Product profiles were compared to samples treated with the so-called COST jet, being introduced by a European COST initiative as a reference device, using both reference conditions as well as conditions adjusted to kINPen gas mixtures. While thiol oxidation was dominant under all tested conditions, an Ar + N2/O2 gas compositions combined with a nitrogen curtain fostered nitric oxide deposition and the desired generation of S-nitrosocysteine. Interestingly, the COST-jet revealed significant differences in its chemical properties in comparison to the kINPen by showing a more stable production of RNS with different gas admixtures, indicating a different •NO production pathway. Taken together, results indicate various chemical properties of kINPen and COST-jet as well as highlight the potential of plasma tuning not only by gas admixtures alone but by adjusting the surrounding atmosphere as well.}, number={5}, journal={PLOS ONE}, author={Lackmann, Jan-Wilm and Bruno, Giuliana and Jablonowski, Helena and Kogelheide, Friederike and Offerhaus, Björn and Held, Julian and Gathen, Volker Schulz-von and Stapelmann, Katharina and Woedtke, Thomas and Wende, Kristian}, editor={Yousfi, MohammedEditor}, year={2019}, month={May}, pages={1–25} }
 @article{śmiłowicz_kogelheide_stapelmann_awakowicz_metzler-nolte_2019, title={Study on Chemical Modifications of Glutathione by Cold Atmospheric Pressure Plasma (Cap) Operated in Air in the Presence of Fe(II) and Fe(III) Complexes}, volume={9}, DOI={10.1038/s41598-019-53538-y}, abstractNote={Abstract Cold atmospheric pressure plasma is an attractive new research area in clinical trials to treat skin diseases. However, the principles of plasma modification of biomolecules in aqueous solutions remain elusive. It is intriguing how reactive oxygen and nitrogen species (RONS) produced by plasma interact on a molecular level in a biological environment. Previously, we identified the chemical effects of dielectric barrier discharges (DBD) on the glutathione (GSH) and glutathione disulphide (GSSG) molecules as the most important redox pair in organisms responsible for detoxification of intracellular reactive species. However, in the human body there are also present redox-active metals such as iron, which is the most abundant transition metal in healthy humans. In the present study, the time-dependent chemical modifications on GSH and GSSG in the presence of iron(II) and iron(III) complexes caused by a dielectric barrier discharge (DBD) under ambient conditions were investigated by IR spectroscopy, mass spectrometry and High Performance Liquid Chromatography (HPLC). HPLC chromatograms revealed one clean peak after treatment of both GSH and GSSH with the dielectric barrier discharge (DBD) plasma, which corresponded to glutathione sulfonic acid GSO 3 H. The ESI-MS measurements confirmed the presence of glutathione sulfonic acid. In our experiments, involving either iron(II) or iron(III) complexes, glutathione sulfonic acid GSO 3 H appeared as the main oxidation product. This is in sharp contrast to GSH/GSSG treatment with DBD plasma in the absence of metal ions, which gave a wild mixture of products. Also interesting, no nitrosylation of GSH/GSSG was oberved in the presence of iron complexes, which seems to indicate a preferential oxygen activation chemistry by this transition metal ion.}, number={1}, journal={Scientific Reports}, publisher={Springer Science and Business Media LLC}, author={Śmiłowicz, Dariusz and Kogelheide, Friederike and Stapelmann, Katharina and Awakowicz, Peter and Metzler-Nolte, Nils}, year={2019} }
 @article{wende_lackmann_jablonowski_stapelmann_woedtke_bekeschus_2018, title={Can We Achieve Selectivity In Plasma Medicine?}, volume={9}, DOI={10.1016/j.cpme.2017.12.067}, abstractNote={Cold physical plasmas have made a remarkable progress over the last few years and are increasingly established in clinics. Especially in chronic wound care and in palliative cancer treatment plasma has a firm foothold [1, 2]. However, the underlying mechanisms have not been completely understood [3, 4]. In the gas phase of cold plasmas, various chemical entities (electrons, ions, metastables, radicals) can be quantified which subsequently interact with an aqueous or biomolecule dominated interfacial layer. The prevailing secondary species of such encounter are matter of debate, with proposed short lived OH, 1O2, O, e-, H, medium lived NO, OCl-, O3, ONOO-, NO2-, and +/- persistent candidates NO3- or H2O2 for aqueous systems [5]. In the case of separate plasma treatment (creating plasma treated liquids) only a few species are stable enough to finally interact clinically or experimentally with a desired target [6, 7]. Similarly, in the case of the direct treatment, the resulting (or remaining) active species and their propagation in gel-like biomolecule matrices, seems to be limited to stable species. Contrasting these experimental results and conclusions, cold plasma has been deployed successfully in a number of completely different conditions. In all cases research points towards an interference with the cellular redox signaling cascade [8]. Accordingly, it must be asked if 1) a common biological denominator exist in all successful applications, if 2) the composition of the plasma treated liquid or the biomolecule matrix in direct treatment determines the effect of the plasma, if 3) the treated tissue itself determines the impact and effectivity of the treatment, or if all aspects add proportionately to the plasmas clinical effectivity. If one (or all) statements are true, it appears that i) plasma source design is subordinate, ii) selectivity is determined by the target and not the treatment, and iii) cold plasma delivers an impulse rather than a substantial dose. To respond to these theses satisfactorily, our research applying multicellular organoid/animal models and complex biochemical models in order to seek for primary or secondary signs of redox signaling and its potential precursors or conditions [9]. Standardized protocols are used to determine the biochemical equivalence of different plasma sources and to infer on their clinical impact. It can be stated so far, that a cells or tissues properties, e.g. origin, protein content, or membrane composition, massively renders the biological impact of a plasma treatment. On the other hand, different chemical fingerprints have been obtained for various plasma sources, fueling engineering approaches to tailor selective plasma sources.}, journal={Clinical Plasma Medicine}, publisher={Elsevier BV}, author={Wende, Kristian and Lackmann, Jan-Wilm and Jablonowski, Helena and Stapelmann, Katharina and Woedtke, Thomas and Bekeschus, Sander}, year={2018}, month={Feb}, pages={43} }
 @article{lackmann_wende_verlackt_golda_volzke_kogelheide_held_bekeschus_bogaerts_gathen_et al._2018, title={Chemical fingerprints of cold physical plasmas - an experimental and computational study using cysteine as tracer compound}, volume={8}, ISSN={["2045-2322"]}, url={https://publons.com/wos-op/publon/2381126/}, DOI={10.1038/s41598-018-25937-0}, abstractNote={Abstract Reactive oxygen and nitrogen species released by cold physical plasma are being proposed as effectors in various clinical conditions connected to inflammatory processes. As these plasmas can be tailored in a wide range, models to compare and control their biochemical footprint are desired to infer on the molecular mechanisms underlying the observed effects and to enable the discrimination between different plasma sources. Here, an improved model to trace short-lived reactive species is presented. Using FTIR, high-resolution mass spectrometry, and molecular dynamics computational simulation, covalent modifications of cysteine treated with different plasmas were deciphered and the respective product pattern used to generate a fingerprint of each plasma source. Such, our experimental model allows a fast and reliable grading of the chemical potential of plasmas used for medical purposes. Major reaction products were identified to be cysteine sulfonic acid, cystine, and cysteine fragments. Less-abundant products, such as oxidized cystine derivatives or S-nitrosylated cysteines, were unique to different plasma sources or operating conditions. The data collected point at hydroxyl radicals, atomic O, and singlet oxygen as major contributing species that enable an impact on cellular thiol groups when applying cold plasma in vitro or in vivo .}, number={1}, journal={SCIENTIFIC REPORTS}, publisher={Springer Nature}, author={Lackmann, J. -W. and Wende, K. and Verlackt, C. and Golda, J. and Volzke, J. and Kogelheide, F. and Held, J. and Bekeschus, S. and Bogaerts, A. and Gathen, V. and et al.}, year={2018}, month={May} }
 @article{zammuto_fuchs_fiebrandt_stapelmann_ulrich_maugeri_pukall_gugliandolo_moeller_2018, title={Comparing Spore Resistance of Bacillus Strains Isolated from Hydrothermal Vents and Spacecraft Assembly Facilities to Environmental Stressors and Decontamination Treatments}, volume={10}, url={https://publons.com/wos-op/publon/10782977/}, DOI={10.1089/ast.2017.1715}, abstractNote={Submarine hydrothermal vents are inhabited by a variety of microorganisms capable of tolerating environmental extremes, making them ideal candidates to further expand our knowledge of the limitations for terrestrial life, including their ability to survive the exposure of spaceflight-relevant conditions. The spore resistance of two Bacillus spp. strains, APA and SBP3, isolated from two shallow vents off Panarea Island (Aeolian Islands, Italy), to artificial and environmental stressors (i.e., UVC radiation, X-rays, heat, space vacuum, hydrogen peroxide [H2O2], and low-pressure plasma), was compared with that of two close phylogenetic relatives (Bacillus horneckiae and Bacillus oceanisediminis). Additional comparisons were made with Bacillus sp. isolated from spacecraft assembly facilities (B. horneckiae, Bacillus pumilus SAFR-032, and Bacillus nealsonii) and the biodosimetry strain and space microbiology model organism Bacillus subtilis. Overall, a high degree of spore resistance to stressors was observed for the strains isolated from spacecraft assembly facilities, with an exceptional level of resistance seen by B. pumilus SAFR-032. The environmental isolate SBP3 showed a more robust spore resistance to UVC, X-rays, H2O2, dry heat, and space vacuum than the closely related B. horneckiae. Both strains (SBP3 and APA) were more thermotolerant than their relatives, B. horneckiae and B. oceanisediminis, respectively. SBP3 may have a novel use as a bacterial model organism for future interrogations into the potential of forward contamination in extraterrestrial environments (e.g., icy moons of Jupiter or Saturn), spacecraft sterilization and, broadly, microbial responses to spaceflight-relevant environmental stressors.}, number={11}, journal={Astrobiology}, publisher={Mary Ann Liebert Inc}, author={Zammuto, Vincenzo and Fuchs, Felix M. and Fiebrandt, Marcel and Stapelmann, Katharina and Ulrich, Nikea J. and Maugeri, Teresa L. and Pukall, Rüdiger and Gugliandolo, Concetta and Moeller, Ralf}, year={2018}, month={Oct}, pages={1425–1434} }
 @article{stapelmann_yusopov_razzokov_bogaerts_lackmann_2018, title={Computational And Experimental Study Of The Impact Of Plasma On The Human Epidermal Growth Factor And Its Implications For Wound Healing And Cancer Treatment}, volume={9}, DOI={10.1016/j.cpme.2017.12.018}, abstractNote={The human epidermal growth factor (hEGF) plays an important role in wound healing as well as in cancer treatment. It is known to trigger chemotaxis, mitogenesis, motogenesis, and cytoprotection, allowing the promotion of cancer growth [1]. On the other hand, exactly these triggers are beneficial for wound healing [2]. Previous studies have shown that cold atmospheric pressure plasma (CAP) treatment of proteins can lead to oxidation, causing structural and conformational changes [3]. In this study, we perform computer simulations and experiments to investigate the impact of plasma treatment on hEGF. Conformational changes with different degrees of oxidation, corresponding to short or longer CAP treatment times, are studied by combining simulation results with Fourier transform infrared spectroscopy. Additional experiments are performed with circular dichroism spectroscopy to verify the simulated conformational changes. The results, being qualitatively in good agreement, indicate a more flexible structure after oxidization, due to conformational changes and breakage of disulfide bonds. Docking simulations reveal that a low oxidation degree does not have a significant influence on the binding affinity of hEGF to its receptor. However, a highly oxidized hEGF exhibits less interaction, probably ultimately affecting cell proliferation by either assisting or inhibiting the process. The results indicate that a low amount of oxidation, comparable to the medical CAP treatment times used for wound healing, does not cause significant changes of the structure of the hEGF protein and thus has only little impact on the interaction of hEGF with its receptor. A significant effect on the structural conformation of hEGF and the binding energy with EGFR can be achieved by higher oxidation degrees, which might ultimately lead to inhibition of cell growth or proliferation. This might be important in cancer treatment by means of CAP, as higher doses of oxidation arrest the cell growth, leading to apoptosis or even necrosis [4,5,6].}, journal={Clinical Plasma Medicine}, publisher={Elsevier BV}, author={Stapelmann, Katharina and Yusopov, Maksudbek and Razzokov, Jamoliddin and Bogaerts, Annemie and Lackmann, Jan-Wilm}, year={2018}, month={Feb}, pages={12} }
 @article{fiebrandt_lackmann_stapelmann_2018, title={From patent to product? 50 years of low-pressure plasma sterilization}, volume={10}, DOI={10.1002/ppap.201800139}, abstractNote={The development of new sterilization methods is still a major topic. The need for new techniques arises from the development of new instruments and the usage of different materials. Especially in the case of plastics with their beneficial properties, for example, in the field of implantology, plasma sterilization is seen as a promising alternative to the standard methods. However, 50 years after the first patent and although low‐pressure plasmas show excellent inactivation performance (>log 6 reduction), only one commercial system is available on the market for a distinct application. We will give a short review about known plasma sterilization mechanisms, the different plasma sterilization systems in use, analyze possible challenges for an industrial process and comment on possible solutions for a broader acceptance and utilization of low‐pressure plasma sterilization.}, journal={Plasma Processes and Polymers}, publisher={Wiley}, author={Fiebrandt, Marcel and Lackmann, Jan-Wilm and Stapelmann, Katharina}, year={2018}, month={Oct}, pages={e1800139} }
 @article{yusupov_lackmann_razzokov_kumar_stapelmann_bogaerts_2018, title={Impact of plasma oxidation on structural features of human epidermal growth factor}, volume={5}, url={https://publons.com/wos-op/publon/1413042/}, DOI={10.1002/ppap.201800022}, abstractNote={Funding information Fonds Wetenschappelijk Onderzoek, Grant number: 1200216N; Bundesministerium für Bildung und Forschung, Grant number: 03Z22DN12 We perform computer simulations supported by experiments to investigate the oxidation of an important signaling protein, that is, human epidermal growth factor (hEGF), caused by cold atmospheric plasma (CAP) treatment. Specifically, we study the conformational changes of hEGF with different degrees of oxidation, to mimic short and long CAP treatment times. Our results indicate that the oxidized structures become more flexible, due to their conformational changes and breakage of the disulfide bonds, especially at higher oxidation degrees. MM/GBSA calculations reveal that an increasing oxidation level leads to a lower binding free energy of hEGF with its receptor. These results help to understand the fundamentals of the use of CAP for wound healing versus cancer treatment at short and longer treatment times.}, number={8}, journal={Plasma Processes and Polymers}, publisher={Wiley}, author={Yusupov, Maksudbek and Lackmann, Jan-Wilm and Razzokov, Jamoliddin and Kumar, Surendra and Stapelmann, Katharina and Bogaerts, Annemie}, year={2018}, month={May}, pages={e1800022} }
 @article{fiebrandt_hillebrand_lackmann_raguse_moeller_awakowicz_stapelmann_2018, title={Inactivation of B. subtilis spores by low pressure plasma-influence of optical filters and photon/particle fluxes on the inactivation efficiency}, volume={51}, ISSN={["1361-6463"]}, url={https://doi.org/10.1088/1361-6463/aa9f0a}, DOI={10.1088/1361-6463/aa9f0a}, abstractNote={Inactivation experiments were performed with Bacillus subtilis spores in a low pressure double inductively coupled plasma (DICP) system. Argon, nitrogen and oxygen at 5 Pa were used as feed gas to change the emission spectrum in the range of 100 nm to 400 nm, as well as between radical and metastable densities. Optical filters were applied, to block particles and selected wavelengths from the spores. By determining absolute photon fluxes, the sporicidal efficiency of various wavelength ranges was evaluated. The results showed good agreement with other plasma experiments, as well as with monochromatic light inactivation experiments from a synchrotron. The findings indicated that the inactivation rate constants of broadband plasma emission and monochromatic light were identical, and that no synergistic effect exists. Furthermore, the influence of radicals, ions and metastables on the inactivation efficiency was of minor importance in the set-up used, and radiation was the main reason for spore inactivation.}, number={4}, journal={JOURNAL OF PHYSICS D-APPLIED PHYSICS}, publisher={IOP Publishing}, author={Fiebrandt, Marcel and Hillebrand, Bastian and Lackmann, Jan-Wilm and Raguse, Marina and Moeller, Ralf and Awakowicz, Peter and Stapelmann, Katharina}, year={2018}, month={Jan} }
 @article{lackmann_klinkhammer_verlackt_jabloniwski_kogelheide_stapelmann_bogaerts_havenith_weltmann_wende_2018, title={Modulating Plasma-Induced Thiol Chemistry In Liquids}, volume={9}, DOI={10.1016/j.cpme.2017.12.060}, abstractNote={Cold physical plasmas are currently under investigation in various fields of industry and medicine. Clinical trials using plasma for wound healing are well under way. In addition, investigations of plasmas for cancer treatment offer promising findings, too. However, the chemical interactions between plasmas and their biological targets are only partly understood. The complex chemical cocktails generated by plasma can affect various biological structures [1]. A better understanding of these reactions would allow tuning and modulating plasmas for specific tasks, e.g. triggering wound healing or apoptosis cascades. One prevalent impact of plasma on biological targets is the chemical modification of thiol groups, which carry out various critical functions in the human body, such as cell signaling and protein structure formation. As thiols are involved in many regulatory and functional processes in tissues, an in-depth understanding of the impact of plasma treatment on thiols is highly relevant to optimize plasmas for medical applications. To shed light onto these interactions, various thiol-containing model substrates were investigated with different plasma sources [2,3]. Using a normalized target substrate, the impact of the different plasma sources can be compared not by means of a physical characterization but by their chemical impact [4]. Stepwise increase of sample complexity allows monitoring how thiols are affected by plasma treatment in an ever more complex environment. The combination of experimental evidence and MD simulations permit a comprehensive overview of chemical processes induced by plasma treatment. This combined approach allows for a more throughout investigation of modifications on a molecular level and helps to understand fundamental plasma chemistry processes. Knowledge how different targets, ranging from small molecules to various proteins are affected by plasma treatment helps to understand how subsequent cellular responses can be triggered and what cross-reactions might be expected by plasma treatment.}, journal={Clinical Plasma Medicine}, publisher={Elsevier BV}, author={Lackmann, Jan-Wilm and Klinkhammer, Christina and Verlackt, Christof and Jabloniwski, Helena and Kogelheide, Friederike and Stapelmann, Katharina and Bogaerts, Annemie and Havenith, Martina and Weltmann, Klaus-Dieter and Wende, Kristian}, year={2018}, month={Feb}, pages={38–39} }
 @article{raguse_fuchs_fiebrandt_stapelmann_awakowicz_laue_madela_möller_2017, title={"Killing them softly" ...}, url={https://elib.dlr.de/118083/1/ME-SBA-2017-Raguse-Moeller-Biotechnology-WMB2017.pdf}, author={Raguse, Marina and Fuchs, Felix Matthias and Fiebrandt, Marcel and Stapelmann, Katharina and Awakowicz, Peter and Laue, Michael and Madela, Kazimierz and Möller, Ralf}, year={2017} }
 @article{stapelmann_fiebrandt_raguse_lackmann_postema_moeller_awakowicz_2017, title={A combined low-pressure hydrogen peroxide evaporation plus hydrogen plasma treatment method for sterilization - Part 1: Characterization of the condensation process and proof-of-concept}, volume={14}, ISSN={["1612-8869"]}, url={https://publons.com/wos-op/publon/571115/}, DOI={10.1002/ppap.201600198}, abstractNote={A combined hydrogen peroxide evaporation and hydrogen low-pressure plasma treatment process for sterilization is introduced and investigated. The combination of hydrogen peroxide evaporation followed by hydrogen plasma treatment offers an advantage regarding sterilization in complex metal geometries or in sealed sterile bags, where plasma treatment alone faces challenges. Within this contribution, the droplet size and film homogeneity after condensation is investigated by optical diagnostics. Sterilization tests with common challenge organisms show the sterilization capabilities of the combined process in a process challenge device, mimicking the worst-case-scenario for plasma treatment in a small metal box. Furthermore, sterilization in sealed sterile bags clearly demonstrates the advantage of the combined process, showing full spore inactivation solely for the combined process.}, number={8}, journal={PLASMA PROCESSES AND POLYMERS}, publisher={Wiley-Blackwell}, author={Stapelmann, Katharina and Fiebrandt, Marcel and Raguse, Marina and Lackmann, Jan-Wilm and Postema, Michiel and Moeller, Ralf and Awakowicz, Peter}, year={2017}, month={Aug} }
 @article{lackmann_fiebrandt_raguse_kartaschew_havenith_bandow_moeller_awakowicz_stapelmann_2017, title={A combined low-pressure hydrogen peroxide evaporation plus hydrogen plasma treatment method for sterilization - Part 2: An intercomparison study of different biological systems}, volume={14}, ISSN={["1612-8869"]}, url={https://publons.com/wos-op/publon/993828/}, DOI={10.1002/ppap.201600199}, abstractNote={Low-pressure plasmas are a promising alternative to modern sterilization processes. As plasma is a surface process, multilayered stacks of spores are a crucial challenge to overcome. Here, a combined process of condensed hydrogen peroxide and hydrogen plasma is analyzed for its efficacy against various spore concentrations showing a clear increase in efficacy using a combined process compared to the two steps used separately. Besides spores, protein contaminations are a major issue in clinics and the combined process is investigated for protein removal efficiency using the well-established BSA model. Furthermore, RNase A serves as a difficult-to-inactivate protein model to investigate protein inactivation efficiency. Finally, inactivation mechanisms of RNase A with a special focus on sulfur-based modifications are investigated using Raman spectroscopy.}, number={8}, journal={PLASMA PROCESSES AND POLYMERS}, publisher={Wiley-Blackwell}, author={Lackmann, Jan-Wilm and Fiebrandt, Marcel and Raguse, Marina and Kartaschew, Konstantin and Havenith, Martina and Bandow, Julia E. and Moeller, Ralf and Awakowicz, Peter and Stapelmann, Katharina}, year={2017}, month={Aug} }
 @inproceedings{smith_kemaneci_offerhaus_kogelheide_bibinov_awakowicz_brinkmann_stapelmann_2017, title={Comparison of zero dimensional plasma chemistry model with ozone absorption spectroscopy measurements}, url={https://meetings.aps.org/Meeting/GEC17/Session/NW1.24}, booktitle={70th Annual Gaseous Electronics Conference}, author={Smith, Ryan and Kemaneci, Efe and Offerhaus, Björn and Kogelheide, Friederike and Bibinov, Nikita and Awakowicz, Peter and Brinkmann, Ralf Peter and Stapelmann, Katharina}, year={2017} }
 @article{klinkhammer_verlackt_smilowicz_kogelheide_bogaerts_metzler-nolte_stapelmann_havenith_lackmann_2017, title={Elucidation of Plasma-induced Chemical Modifications on Glutathione and Glutathione Disulphide}, volume={7}, ISSN={["2045-2322"]}, url={https://publons.com/wos-op/publon/10782978/}, DOI={10.1038/s41598-017-13041-8}, abstractNote={Cold atmospheric pressure plasmas are gaining increased interest in the medical sector and clinical trials to treat skin diseases are underway. Plasmas are capable of producing several reactive oxygen and nitrogen species (RONS). However, there are open questions how plasma-generated RONS interact on a molecular level in a biological environment, e.g. cells or cell components. The redox pair glutathione (GSH) and glutathione disulphide (GSSG) forms the most important redox buffer in organisms responsible for detoxification of intracellular reactive species. We apply Raman spectroscopy, mass spectrometry, and molecular dynamics simulations to identify the time-dependent chemical modifications on GSH and GSSG that are caused by dielectric barrier discharge under ambient conditions. We find GSSG, S-oxidised glutathione species, and S-nitrosoglutathione as oxidation products with the latter two being the final products, while glutathione sulphenic acid, glutathione sulphinic acid, and GSSG are rather reaction intermediates. Experiments using stabilized pH conditions revealed the same main oxidation products as were found in unbuffered solution, indicating that the dominant oxidative or nitrosative reactions are not influenced by acidic pH. For more complex systems these results indicate that too long treatment times can cause difficult-to-handle modifications to the cellular redox buffer which can impair proper cellular function.}, number={1}, journal={SCIENTIFIC REPORTS}, publisher={Springer Nature}, author={Klinkhammer, Christina and Verlackt, Christof and Smilowicz, Dariusz and Kogelheide, Friederike and Bogaerts, Annemie and Metzler-Nolte, Nils and Stapelmann, Katharina and Havenith, Martina and Lackmann, Jan-Wilm}, year={2017}, month={Oct} }
 @article{fuchs_raguse_fiebrandt_madela_awakowicz_laue_stapelmann_moeller_2017, title={Investigating the Detrimental Effects of Low Pressure Plasma Sterilization on the Survival of Bacillus subtilis Spores Using Live Cell Microscopy}, volume={11}, ISSN={["1940-087X"]}, url={https://publons.com/wos-op/publon/10782979/}, DOI={10.3791/56666}, abstractNote={Plasma sterilization is a promising alternative to conventional sterilization methods for industrial, clinical, and spaceflight purposes. Low pressure plasma (LPP) discharges contain a broad spectrum of active species, which lead to rapid microbial inactivation. To study the efficiency and mechanisms of sterilization by LPP, we use spores of the test organism Bacillus subtilis because of their extraordinary resistance against conventional sterilization procedures. We describe the production of B. subtilis spore monolayers, the sterilization process by low pressure plasma in a double inductively coupled plasma reactor, the characterization of spore morphology using scanning electron microscopy (SEM), and the analysis of germination and outgrowth of spores by live cell microscopy. A major target of plasma species is genomic material (DNA) and repair of plasma-induced DNA lesions upon spore revival is crucial for survival of the organism. Here, we study the germination capacity of spores and the role of DNA repair during spore germination and outgrowth after treatment with LPP by tracking fluorescently-labelled DNA repair proteins (RecA) with time-resolved confocal fluorescence microscopy. Treated and untreated spore monolayers are activated for germination and visualized with an inverted confocal live cell microscope over time to follow the reaction of individual spores. Our observations reveal that the fraction of germinating and outgrowing spores is dependent on the duration of LPP-treatment reaching a minimum after 120 s. RecA-YFP (yellow fluorescence protein) fluorescence was detected only in few spores and developed in all outgrowing cells with a slight elevation in LPP-treated spores. Moreover, some of the vegetative bacteria derived from LPP-treated spores showed an increase in cytoplasm and tended to lyse. The described methods for analysis of individual spores could be exemplary for the study of other aspects of spore germination and outgrowth.}, number={129}, journal={JOVE-JOURNAL OF VISUALIZED EXPERIMENTS}, publisher={MyJove Corporation}, author={Fuchs, Felix M. and Raguse, Marina and Fiebrandt, Marcel and Madela, Kazimierz and Awakowicz, Peter and Laue, Michael and Stapelmann, Katharina and Moeller, Ralf}, year={2017}, month={Nov} }
 @article{engelhardt_kogelheide_stapelmann_bibinov_awakowicz_2017, title={Micro-plasmoids in self organized filamentary dielectric barrier discharges}, volume={14}, ISSN={["1612-8869"]}, url={https://publons.com/wos-op/publon/627175/}, DOI={10.1002/ppap.201600095}, abstractNote={A filamentary dielectric barrier discharge (DBD) is ignited on a silicon wafer under atmospheric pressure conditions in a mixture of argon and air (0.5/0.5) in two different modes, namely a stochastically ignited filamentary discharge and a self-organized filamentary discharge by the application of high voltage (HV) pulses at two repetition frequencies, 0.5 and 5 kHz. The discharge conditions are characterized by optical emission spectroscopy and current–voltage measurements. The silicon wafer surface treated with the DBD is studied with an electron microscope. The formation of a homogeneous silicon oxide layer is observed after treatment under a stochastically filamentary DBD. Whereas, in the self-organized filamentary DBD, etching tracks (thin channels) and blisters are produced on the silicon wafer surface, which are interpreted as tracks of plasmoids, namely plasma objects without any direct contact to a power supply. The transition between the different filamentary modes of the DBD plasma occurs in the presented study through an increase of the repetition frequency of HV pulses, but it can also be caused by small silicon splinters on the wafer surface. The splinters cause ignitions in stable positions, and therefore induce a combination of discharge modes, namely stochastically and self-organized DBD mode. In close proximity to the splinters, tracks of plasmoids are observed, even in the DBD at low frequency.}, number={7}, journal={PLASMA PROCESSES AND POLYMERS}, publisher={Wiley-Blackwell}, author={Engelhardt, Max and Kogelheide, Friederike and Stapelmann, Katharina and Bibinov, Nikita and Awakowicz, Peter}, year={2017}, month={Jul} }
 @article{offerhaus_lackmann_kogelheide_bracht_smith_bibinov_stapelmann_awakowicz_2017, title={Spatially resolved measurements of the physical plasma parameters and the chemical modifications in a twin surface dielectric barrier discharge for gas flow purification}, volume={14}, ISSN={["1612-8869"]}, url={https://doi.org/10.1002/ppap.201600255}, DOI={10.1002/ppap.201600255}, abstractNote={A twin surface dielectric barrier discharge consisting of an aluminium oxide plate with grid-structured copper traces on both sides is presented. Due to the size of the electrode configuration spatially resolved optical emission spectroscopy for characterisation of the discharge is performed on two different length scales in order to show its homogeneous behaviour. A broadband echelle spectrometer is employed for a comparison of the plasma parameters at different sites along the copper traces with a spatial resolution on a scale of millimetres. In addition, an ICCD camera with bandpass filters yields homogeneity of the plasma parameters on a scale of micrometres at a given node of the grid-structured copper traces. The discharge is shown to be homogeneous all along the electrode. However, due to the changing composition of the gas stream, it cannot be concluded that the gas phase chemistry follows the same trend. Therefore, FTIR spectroscopy of cysteine is used to monitor the spatial dependence of the gas phase chemistry, showing a transition from purely oxygen-related modifications at the front of the electrode to a mixture of oxygen-related and nitrogen-related modifications at the rear.}, number={10}, journal={PLASMA PROCESSES AND POLYMERS}, publisher={Wiley-Blackwell}, author={Offerhaus, Bjoern and Lackmann, Jan-Wilm and Kogelheide, Friederike and Bracht, Vera and Smith, Ryan and Bibinov, Nikita and Stapelmann, Katharina and Awakowicz, Peter}, year={2017}, month={Oct} }
 @article{fiebrandt_lackmann_raguse_moeller_awakowicz_stapelmann_2017, title={VUV absorption spectroscopy of bacterial spores and DNA components}, volume={59}, ISSN={["1361-6587"]}, url={https://publons.com/wos-op/publon/627174/}, DOI={10.1088/0741-3335/59/1/014010}, abstractNote={Low-pressure plasmas can be used to inactivate bacterial spores and sterilize goods for medical and pharmaceutical applications. A crucial factor are damages induced by UV and VUV radiation emitted by the plasma. To analyze inactivation processes and protection strategies of spores, absorption spectra of two B. subtilis strains are measured. The results indicate, that the inner and outer coat of the spore significantly contribute to the absorption of UV-C and also of the VUV, protecting the spore against radiation based damages. As the sample preparation can significantly influence the absorption spectra due to salt residues, the cleaning procedure and sample deposition is tested for its reproducibility by measuring DNA oligomers and pUC18 plasmid DNA. The measurements are compared and discussed with results from the literature, showing a strong decrease of the salt content enabling the detection of absorption structures in the samples.}, number={1}, journal={PLASMA PHYSICS AND CONTROLLED FUSION}, publisher={IOP Publishing}, author={Fiebrandt, Marcel and Lackmann, Jan-Wilm and Raguse, Marina and Moeller, Ralf and Awakowicz, Peter and Stapelmann, Katharina}, year={2017}, month={Jan} }
 @inproceedings{offerhaus_kogelheide_lackmann_bibinov_stapelmann_awakowicz_smith_bracht_2016, title={Characterisation of a dielectric barrier surface twin discharge using defined gas mixtures}, url={http://meetings.aps.org/Meeting/GEC16/Session/MW6.64}, booktitle={69th Annual Gaseous Electronics Conference}, author={Offerhaus, Björn and Kogelheide, Friederike and Lackmann, Jan-Wilm and Bibinov, Nikita and Stapelmann, Katharina and Awakowicz, Peter and Smith, Ryan and Bracht, Vera}, year={2016} }
 @inproceedings{kogelheide_offerhaus_bibinov_lackmann_awakowicz_stapelmann_bracht_smith_2016, title={Characterization of a dielectric barrier discharge in controlled atmosphere}, url={http://meetings.aps.org/Meeting/GEC16/Session/MW6.65}, booktitle={69th Annual Gaseous Electronics Conference}, author={Kogelheide, Friederike and Offerhaus, Björn and Bibinov, Nikita and Lackmann, Jan-Wilm and Awakowicz, Peter and Stapelmann, Katharina and Bracht, Vera and Smith, Ryan}, year={2016} }
 @article{schirmack_fiebrandt_stapelmann_schulze-makuch_2016, title={Effects of Low-Temperature Plasma-Sterilization on Mars Analog Soil Samples Mixed with Deinococcus radiodurans}, volume={6}, url={https://publons.com/wos-op/publon/627172/}, DOI={10.3390/life6020022}, abstractNote={We used Ar plasma-sterilization at a temperature below 80 °C to examine its effects on the viability of microorganisms when intermixed with tested soil. Due to a relatively low temperature, this method is not thought to affect the properties of a soil, particularly its organic component, to a significant degree. The method has previously been shown to work well on spacecraft parts. The selected microorganism for this test was Deinococcus radiodurans R1, which is known for its remarkable resistance to radiation effects. Our results showed a reduction in microbial counts after applying a low temperature plasma, but not to a degree suitable for a sterilization of the soil. Even an increase of the treatment duration from 1.5 to 45 min did not achieve satisfying results, but only resulted in in a mean cell reduction rate of 75% compared to the untreated control samples.}, number={2}, journal={Life}, publisher={MDPI AG}, author={Schirmack, Janosch and Fiebrandt, Marcel and Stapelmann, Katharina and Schulze-Makuch, Dirk}, year={2016}, month={May}, pages={22} }
 @article{kogelheide_kartaschew_strack_baldus_metzler-nolte_havenith_awakowicz_stapelmann_lackmann_2016, title={FTIR spectroscopy of cysteine as a ready-to-use method for the investigation of plasma-induced chemical modifications of macromolecules}, volume={49}, ISSN={["1361-6463"]}, url={https://publons.com/wos-op/publon/627180/}, DOI={10.1088/0022-3727/49/8/084004}, abstractNote={A rapid screening method for the investigation of plasma-induced chemical modifications was developed by analyzing cysteine using Fourier Transform Infrared (FTIR) spectroscopy. Cysteine is a key amino acid in proteins due to the presence of a thiol group which provides unique structural features by offering the possibility to form disulfide bonds. Its chemical composition makes cysteine a well-suited model for the investigation of plasma-induced modifications at three functional groups—the amino, the carboxyl and the thiol group—all highly abundant in proteins. FTIR spectroscopy is present in most physical laboratories and offers a fast way to assess changes in the chemical composition of cysteine substrates due to plasma treatment and to compare different treatment conditions or plasma sources with each other. Significant changes in the fingerprint spectra of cysteine samples treated with a dielectric barrier discharge (DBD) compared to untreated controls were observed using a FTIR spectrometer. The loss of the thiol signal and the simultaneous increase of bands originating from oxidized sulfur and nitrogen species indicate that the thiol group of cysteine is modified by reactive oxygen and nitrogen species during DBD treatment. Furthermore, other plasma-induced modifications, such as changes of the amino and carbonyl groups, could be observed. Complementary mass spectrometry measurements confirmed these results.}, number={8}, journal={JOURNAL OF PHYSICS D-APPLIED PHYSICS}, publisher={IOP Publishing}, author={Kogelheide, Friederike and Kartaschew, Konstantin and Strack, Martin and Baldus, Sabrina and Metzler-Nolte, Nils and Havenith, Martina and Awakowicz, Peter and Stapelmann, Katharina and Lackmann, Jan-Wilm}, year={2016}, month={Mar} }
 @article{raguse_fiebrandt_stapelmann_madela_laue_lackmann_thwaite_setlow_awakowicz_moeller_et al._2016, title={Improvement of Biological Indicators by Uniformly Distributing Bacillus subtilis Spores in Monolayers To Evaluate Enhanced Spore Decontamination Technologies}, volume={82}, ISSN={["1098-5336"]}, url={https://publons.com/wos-op/publon/627177/}, DOI={10.1128/aem.03934-15}, abstractNote={ABSTRACT Novel decontamination technologies, including cold low-pressure plasma and blue light (400 nm), are promising alternatives to conventional surface decontamination methods. However, the standardization of the assessment of such sterilization processes remains to be accomplished. Bacterial endospores of the genera Bacillus and Geobacillus are frequently used as biological indicators (BIs) of sterility. Ensuring standardized and reproducible BIs for reliable testing procedures is a significant problem in industrial settings. In this study, an electrically driven spray deposition device was developed, allowing fast, reproducible, and homogeneous preparation of Bacillus subtilis 168 spore monolayers on glass surfaces. A detailed description of the structural design as well as the operating principle of the spraying device is given. The reproducible formation of spore monolayers of up to 5 × 107 spores per sample was verified by scanning electron microscopy. Surface inactivation studies revealed that monolayered spores were inactivated by UV-C (254 nm), low-pressure argon plasma (500 W, 10 Pa, 100 standard cubic cm per min), and blue light (400 nm) significantly faster than multilayered spores were. We have thus succeeded in the uniform preparation of reproducible, highly concentrated spore monolayers with the potential to generate BIs for a variety of nonpenetrating surface decontamination techniques.}, number={7}, journal={APPLIED AND ENVIRONMENTAL MICROBIOLOGY}, publisher={American Society for Microbiology}, author={Raguse, Marina and Fiebrandt, Marcel and Stapelmann, Katharina and Madela, Kazimierz and Laue, Michael and Lackmann, Jan-Wilm and Thwaite, Joanne E. and Setlow, Peter and Awakowicz, Peter and Moeller, Ralf and et al.}, editor={Schaffner, D. W.Editor}, year={2016}, month={Apr}, pages={2031–2038} }
 @inproceedings{stapelmann_kogelheide_baldus_lackmann_awakowicz_kartaschew_havenith_schröder_gathen_suschek_et al._2016, title={It's all about NO?}, url={http://meetings.aps.org/Meeting/GEC16/Session/SR3.5}, booktitle={69th Annual Gaseous Electronics Conference}, author={Stapelmann, Katharina and Kogelheide, Friederike and Baldus, Sabrina and Lackmann, Jan-Wilm and Awakowicz, Peter and Kartaschew, Konstantin and Havenith, Martina and Schröder, Daniel and Gathen, Volker Schulz-von and Suschek, Christoph V. and et al.}, year={2016} }
 @article{raguse_fiebrandt_denis_stapelmann_eichenberger_driks_eaton_awakowicz_moeller_2016, title={Understanding of the importance of the spore coat structure and pigmentation in the Bacillus subtilis spore resistance to low-pressure plasma sterilization}, volume={49}, ISSN={["1361-6463"]}, url={https://publons.com/wos-op/publon/627173/}, DOI={10.1088/0022-3727/49/28/285401}, abstractNote={Low-pressure plasmas have been evaluated for their potential in biomedical and defense purposes. The sterilizing effect of plasma can be attributed to several active agents, including (V)UV radiation, charged particles, radical species, neutral and excited atoms and molecules, and the electric field. Spores of Bacillus subtilis were used as a bioindicator and a genetic model system to study the sporicidal effects of low-pressure plasma decontamination. Wild-type spores, spores lacking the major protective coat layers (inner, outer, and crust), pigmentation-deficient spores or spore impaired in encasement (a late step in coat assembly) were systematically tested for their resistance to low-pressure argon, hydrogen, and oxygen plasmas with and without admixtures. We demonstrate that low-pressure plasma discharges of argon and oxygen discharges cause significant physical damage to spore surface structures as visualized by atomic force microscopy. Spore resistance to low-pressure plasma was primarily dependent on the presence of the inner, and outer spore coat layers as well as spore encasement, with minor or less importance of the crust and spore pigmentation, whereas spore inactivation itself was strongly influenced by the gas composition and operational settings.}, number={28}, journal={JOURNAL OF PHYSICS D-APPLIED PHYSICS}, publisher={IOP Publishing}, author={Raguse, Marina and Fiebrandt, Marcel and Denis, Benjamin and Stapelmann, Katharina and Eichenberger, Patrick and Driks, Adam and Eaton, Peter and Awakowicz, Peter and Moeller, Ralf}, year={2016}, month={Jul} }
 @inproceedings{smith_kemaneci_offerhaus_stapelmann_brinkmann_2016, title={Zero dimensional model of atmospheric SMD discharge and afterglow in humid air}, url={https://publons.com/wos-op/publon/10782980/}, DOI={10.1109/plasma.2016.7534332}, abstractNote={Summary form only given. Multiple time-scaled zero-dimensional models are used to simulate the time resolved number densities of multiple reactive oxygen and nitrogen species(RONs), including O3, NO2, NO3, N2O, N2O5, H2O2, HNO2 and HNO3, in a humid air plasma process at atmospheric pressure. Simulated is a total of 26 ionic species, electrons and 26 neutral species including multiple excited states. From the local Electron Energy Distribution Function (EEDF) the mean electron energy is determined and used in various reaction rate coefficients. A total of 624 reactions between the 53 species are simulated in two interdependent zero-dimensional models that differ in nine orders magnitude in temporal resolution, thereby reducing the computational load that is traditionally required in a complex system. A single homogenous volumetric discharge generated by a Surface Micro Discharge(SMD) setup is simulated. Through control variables, parameters such as: ignition frequency, deposited power density, duty cycle, discharge size, and humidity level will be varied in order to predict ideal operating conditions for appropriate SMD devices. The described model has been verified by matching simulation parameters and comparing results to that of previous works1 as well as matching current operating conditions and comparing to the measurements of an experimental mesh-like SMD.}, booktitle={2016 IEEE International Conference on Plasma Science (ICOPS)}, publisher={Institute of Electrical and Electronics Engineers (IEEE)}, author={Smith, Ryan T. and Kemaneci, Efe and Offerhaus, Bjorn and Stapelmann, Katharina and Brinkmann, Ralf-Peter}, year={2016}, month={Jun}, pages={395} }
 @article{stapelmann_fiebrandt_styrnoll_baldus_bibinov_awakowicz_2015, title={Implications of electron heating and non-uniformities in a VHF-CCP for sterilization of medical instruments}, volume={24}, ISSN={["1361-6595"]}, url={https://publons.com/wos-op/publon/627179/}, DOI={10.1088/0963-0252/24/3/034014}, abstractNote={A capacitively coupled plasma driven at a frequency of 81.36 MHz from the VHF-band is investigated by means of optical emission spectroscopy (OES) and multipole resonance probe (MRP). The discharge is operated with hydrogen, yielding an electropositive discharge, as well as oxygen, yielding an electronegative discharge, and mixtures of both. Pressure is varied from p=5 ?> Pa to p=25 ?> Pa. Homogeneity of the discharge is investigated by CCD camera recordings as well as spatially resolved multipole resonance probe measurements. The results indicate the presence of electromagnetic edge effects as well as standing wave effects. Furthermore, a largely homogeneous discharge can be achieved with hydrogen as process gas at a pressure of p=5 ?>–10 Pa. With increasing pressure as well as with increasing oxygen content, the discharge appears less homogeneously. The transition from an electropositive to an electronegative discharge leads to a change in electron heating mechanisms, with pronounced local maxima of electron density at the sheath edges. A comparison of OES and MRP results reveal a significant difference in electron density, which can be explained by a non-Maxwellian distribution function of electrons.}, number={3}, journal={PLASMA SOURCES SCIENCE & TECHNOLOGY}, publisher={IOP Publishing}, author={Stapelmann, Katharina and Fiebrandt, Marcel and Styrnoll, Tim and Baldus, Sabrina and Bibinov, Nikita and Awakowicz, Peter}, year={2015}, month={May} }
 @article{baldus_kogelheide_bibinov_stapelmann_awakowicz_2015, title={Phase resolved analysis of the homogeneity of a diffuse dielectric barrier discharge}, volume={48}, ISSN={["1361-6463"]}, url={https://publons.com/wos-op/publon/627176/}, DOI={10.1088/0022-3727/48/37/375202}, abstractNote={Cold atmospheric pressure plasmas have already proven their ability of supporting the healing process of chronic wounds. Especially simple configurations like a dielectric barrier discharge (DBD), comprising of one driven electrode which is coated with a dielectric layer, are of interest, because they are cost-effective and easy to handle. The homogeneity of such plasmas during treatment is necessary since the whole wound should be treated evenly. In this investigation phase resolved optical emission spectroscopy is used to investigate the homogeneity of a DBD. Electron densities and reduced electric field distributions are determined with temporal and spatial resolution and the differences for applied positive and negative voltage pulses are studied.}, number={37}, journal={JOURNAL OF PHYSICS D-APPLIED PHYSICS}, publisher={IOP Publishing}, author={Baldus, Sabrina and Kogelheide, Friederike and Bibinov, Nikita and Stapelmann, Katharina and Awakowicz, Peter}, year={2015}, month={Sep} }
 @article{stapelmann_lackmann_buerger_bandow_awakowicz_2014, title={A H-2 very high frequency capacitively coupled plasma inactivates glyceraldehyde 3-phosphate dehydrogenase(GapDH) more efficiently than UV photons and heat combined}, volume={47}, ISSN={["1361-6463"]}, url={http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=ORCID&SrcApp=OrcidOrg&DestLinkType=FullRecord&DestApp=WOS_CPL&KeyUT=WOS:000331902900018&KeyUID=WOS:000331902900018}, DOI={10.1088/0022-3727/47/8/085402}, abstractNote={Plasma sterilization is a promising alternative to commonly used sterilization techniques, because the conventional methods suffer from certain limitations, e.g. incompatibility with heat-sensitive materials, or use of toxic agents. However, plasma-based sterilization mechanisms are not fully understood yet. A low-pressure very high frequency capacitively coupled plasma is used to investigate the impact of a hydrogen discharge on the protein glyceraldehyde 3-phosphate dehydrogenase (GapDH). GapDH is an enzyme of glycolysis. As a part of the central metabolism, it occurs in nearly all organisms from bacteria to humans. The plasma is investigated with absolutely calibrated optical emission spectroscopy in order to identify and to quantify plasma components that can contribute to enzyme inactivation. The contribution of UV photons and heat to GapDH inactivation is investigated separately, and neither seems to be a major factor. In order to investigate the mechanisms of GapDH inactivation by the hydrogen discharge, samples are investigated for etching, induction of amino acid backbone breaks, and chemical modifications. While neither etching nor strand breaks are observed, chemical modifications occur at different amino acid residues of GapDH. Deamidations of asparagines as well as methionine and cysteine oxidations are detected after VHF-CCP treatment. In particular, oxidation of the cysteine in the active centre is known to lead to GapDH inactivation.}, number={8}, journal={JOURNAL OF PHYSICS D-APPLIED PHYSICS}, publisher={IOP Publishing}, author={Stapelmann, Katharina and Lackmann, Jan-Wilm and Buerger, Ines and Bandow, Julia Elisabeth and Awakowicz, Peter}, year={2014}, month={Feb} }
 @inproceedings{fiebrandt_stapelmann_bibinov_awakowicz_2013, title={Characterization of a low-pressure VHF-CCP for sterilization pros and cons of a polymer discharge chamber}, url={https://publons.com/wos-op/publon/15867441/}, DOI={10.1109/plasma.2013.6634821}, abstractNote={Summary form only given. As Plasma is known to be very effective against bacteria, spores, fungi and macromolecules, a setup was developed to meet commercial needs. In order to keep sterilized goods sterile after plasma treatment, the discharge chamber can serve as sterile container. This required using a polymer discharge chamber. Since polymer and plasma interact, the plasma composition is strongly influenced by contaminated chamber walls. To study the effects and characterize the plasma, absolutely calibrated optical emission spectroscopy, Langmuir probe measurements, multipole resonance probe measurements and mass spectrometry were performed. The results were linked to biological experiments proving the effectiveness of the setup and improving understanding of sterilization and decontamination mechanisms. The experiments revealed some drawbacks due to plasma-wall interaction, but also possibilities to use the contamination for optimization of the sterilization process.}, booktitle={2013 Abstracts IEEE International Conference on Plasma Science (ICOPS)}, publisher={Institute of Electrical & Electronics Engineers (IEEE)}, author={Fiebrandt, Marcel and Stapelmann, Katharina and Bibinov, Nikita and Awakowicz, Peter}, year={2013}, month={Jun} }
 @inproceedings{stoltz_fiebrandt_stapelmann_awakowicz_2013, title={Improved understanding of electron density and temperature in a low pressure VHF-CCP from kinetic simulation}, url={https://publons.com/wos-op/publon/15867442/}, DOI={10.1109/plasma.2013.6633234}, abstractNote={Summary form only given. Low pressure capacitively coupled plasma discharges are a promising plasma for biomedical applications. However, in recent experiments using a hydrogen gas, electron densities and temperatures from two measurements (multipole resonance probe and optical emission spectroscopy) disagree. Possible explanations for this disagreement include negative ion formation and non-thermal velocity distributions. We use kinetic plasma modeling to help understand this disagreement. In particular we show the effect of the rate of negative ion formation on the overall plasma density, and we estimate the effect of non-thermal electrons on the temperature diagnostics.}, booktitle={2013 Abstracts IEEE International Conference on Plasma Science (ICOPS)}, publisher={Institute of Electrical & Electronics Engineers (IEEE)}, author={Stoltz, Peter H. and Fiebrandt, Marcel and Stapelmann, Katharina and Awakowicz, Peter}, year={2013}, month={Jun} }
 @inproceedings{stapelmann_fiebrandt_burger_awakowicz_lackmann_steinborn_bandow_2013, title={On our way to understand sterilization mechanisms &#x2014; Inactivation and modification of bio-macromolecules by H<inf>2</inf> and O<inf>2</inf> plasma}, DOI={10.1109/plasma.2013.6633303}, abstractNote={A low-pressure VHF-CCP is used to investigate the impact of H2 and O2 plasma on bio-macromolecules. Since both, plasma and cells, are very complex systems, bio-macromolecules are used to identify possible inactivation mechanisms. With the ubiquitous enzyme GAPDH, enzyme activity tests were carried out before and after plasma treatment, revealing that oxygen plasma leads to a higher inactivation than hydrogen plasma. SDS PAGE indicates that neither fragmentation nor unfolding occurs. With mass spectrometry we could identify mainly oxidation of cysteine in case of oxygen plasma as possible inactivation mechanism, whereas in case of hydrogen plasma deamidation takes place. The inactivation results are correlated with plasma parameters, obtained with optical emission spectroscopy.}, booktitle={2013 Abstracts IEEE International Conference on Plasma Science (ICOPS)}, publisher={Institute of Electrical & Electronics Engineers (IEEE)}, author={Stapelmann, Katharina and Fiebrandt, Marcel and Burger, Ines and Awakowicz, Peter and Lackmann, Jan-Wilm and Steinborn, Elena and Bandow, Julia E.}, year={2013}, month={Jun} }
 @phdthesis{informationstechnik_2013, title={Plasma technical and microbiological characterization of newly developed VHF plasmas}, url={http://www-brs.ub.ruhr-uni-bochum.de/netahtml/HSS/Diss/StapelmannKatharina/diss.pdf}, author={Informationstechnik, Fakultät}, year={2013}, month={Dec} }
 @article{stapelmann_fiebrandt_raguse_awakowicz_reitz_moeller_2013, title={Utilization of Low-Pressure Plasma to Inactivate Bacterial Spores on Stainless Steel Screws}, volume={13}, ISSN={["1557-8070"]}, url={http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=ORCID&SrcApp=OrcidOrg&DestLinkType=FullRecord&DestApp=WOS_CPL&KeyUT=WOS:000321896100001&KeyUID=WOS:000321896100001}, DOI={10.1089/ast.2012.0949}, abstractNote={A special focus area of planetary protection is the monitoring, control, and reduction of microbial contaminations that are detected on spacecraft components and hardware during and after assembly. In this study, wild-type spores of Bacillus pumilus SAFR-032 (a persistent spacecraft assembly facility isolate) and the laboratory model organism B. subtilis 168 were used to study the effects of low-pressure plasma, with hydrogen alone and in combination with oxygen and evaporated hydrogen peroxide as a process gas, on spore survival, which was determined by a colony formation assay. Spores of B. pumilus SAFR-032 and B. subtilis 168 were deposited with an aseptic technique onto the surface of stainless steel screws to simulate a spore-contaminated spacecraft hardware component, and were subsequently exposed to different plasmas and hydrogen peroxide conditions in a very high frequency capacitively coupled plasma reactor (VHF-CCP) to reduce the spore burden. Spores of the spacecraft isolate B. pumilus SAFR-032 were significantly more resistant to plasma treatment than spores of B. subtilis 168. The use of low-pressure plasma with an additional treatment of evaporated hydrogen peroxide also led to an enhanced spore inactivation that surpassed either single treatment when applied alone, which indicates the potential application of this method as a fast and suitable way to reduce spore-contaminated spacecraft hardware components for planetary protection purposes.}, number={7}, journal={ASTROBIOLOGY}, publisher={Mary Ann Liebert Inc}, author={Stapelmann, Katharina and Fiebrandt, Marcel and Raguse, Marina and Awakowicz, Peter and Reitz, Guenther and Moeller, Ralf}, year={2013}, month={Jul}, pages={597–606} }
 @inproceedings{stapelmann_bibinov_awakowicz_lackmann_bandow_2012, title={From research to application: Introducing a plasma sterilization prototype}, url={https://publons.com/wos-op/publon/15867443/}, DOI={10.1109/plasma.2012.6383779}, abstractNote={Summary form only given. Plasma sterilization is known to be a promising alternative to common sterilization methods. Although lots of effort has been taken to investigate low-pressure plasma sterilization systems, only little effort has been taken to bring plasma sterilization to market. In this contribution we will present a plasma sterilization prototype for use in medical practice.}, booktitle={2012 Abstracts IEEE International Conference on Plasma Science}, publisher={Institute of Electrical & Electronics Engineers (IEEE)}, author={Stapelmann, K. and Bibinov, N. and Awakowicz, P. and Lackmann, J. and Bandow, J.}, year={2012}, month={Jul}, pages={274} }
 @article{awakowicz_baldus_stapelmann_engelhardt_bibinov_denis_2012, title={Optical Emission Spectroscopy as a Tool for Characterization of Technical Plasmas in Medical Applications}, volume={2}, url={https://publons.com/wos-op/publon/627184/}, DOI={10.1615/plasmamed.2013006849}, abstractNote={Understanding the interactions of technical plasma discharges with biological systems is a key aspect to developing and optimizing plasma devices for use in medical practice. In this article, the characterization of 3 different plasma devices with absolutely and relatively calibrated optical emission spectroscopy is presented. Two low-pressure setups are described: a double inductively coupled plasma that serves as laboratory setup for basic research of sterilization of spores and germs and a very high frequency capacitively coupled plasma designed to meet commercial needs. An atmospheric pressure dielectric barrier discharge is designed for wound and skin treatment. Sterilization tests for each setup demonstrate the capability to inactivate bacteria and bacterial spores efficiently. In case of the double inductively coupled plasma, wavelength-dependent photo sterilization efficiency is investigated. As a result, Aspergillus brasiliensis spores are efficiently inactivated by irradiation below 235 nm, whereas Bacillus atrophaeus spores are sensitive to irradiation between 235 and 300 nm. The very high frequency capacitively coupled plasma demonstrates a reduction greater than log 6 of B. Atrophaeus endospores in a process challenge device, a metal box with 3 small slits (3 mm). With direct DBD treatment, a full inactivation of Escherichia coli is achieved within 10 seconds of treatment time. From measurements, data can be extracted only at certain positions. Simulations deliver spatially resolved data from whole-discharge volume.}, number={1-3}, journal={Plasma Med}, publisher={Begell House}, author={Awakowicz, Peter and Baldus, Sabrina and Stapelmann, Katharina and Engelhardt, Max and Bibinov, Nikita and Denis, Benjamin}, year={2012}, pages={151–168} }
 @article{kylian_denis_stapelmann_ruiz_rauscher_rossi_2011, title={Characterization of a Low-pressure Inductively Coupled Plasma Discharge Sustained in Ar/O2/N2 Ternary Mixtures and Evaluation of its Effect on Erosion of Biological Samples}, volume={8}, ISSN={["1612-8850"]}, url={http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=ORCID&SrcApp=OrcidOrg&DestLinkType=FullRecord&DestApp=WOS_CPL&KeyUT=WOS:000298354000005&KeyUID=WOS:000298354000005}, DOI={10.1002/ppap.201100086}, abstractNote={Abstract Detailed characterization of a low‐pressure inductively coupled plasma discharge sustained in an Ar/O 2 /N 2 ternary mixture is performed in this study. The main attention is devoted to the evaluation of the dependence of parameters important for treatment of biological samples (emission of UV radiation, plasma density, energy of charged particles, O atoms density, and substrate heating) on the working gas mixture composition. Subsequently, the capability of plasma sustained in ternary gas mixture to effectively etch biological contaminants is tested on examples of bacterial spores and poly‐ L ‐histidine. magnified image}, number={12}, journal={PLASMA PROCESSES AND POLYMERS}, publisher={Wiley-Blackwell}, author={Kylian, Ondrej and Denis, Benjamin and Stapelmann, Katharina and Ruiz, Ana and Rauscher, Hubert and Rossi, Francois}, year={2011}, month={Dec}, pages={1137–1145} }
 @inproceedings{stapelmann_lackmann_bibinov_bandow_postema_awakowicz_2011, title={Characterization of a novel VHF-CCP for sterilization and decontamination of medical instruments}, url={http://www.ispc-conference.org/ispcproc/ispc20/368.pdf}, booktitle={20nd International Symposium on Plasma Chemistry (ISPC-20), Philadelphia, Pennsylvania, USA, 2011}, author={Stapelmann, Katharina and Lackmann, Jan-Wilm and Bibinov, Nikita and Bandow, Julia E and Postema, Michiel and Awakowicz, Peter}, year={2011} }
 @inproceedings{lackmann_stapelmann_narberhaus_awakowicz_bandow_2011, title={In vitro characterization of bacterial macromolecule damage induced by low-pressure VHF-CCP plasma}, url={http://www.ispc-conference.org/ispcproc/ispc20/532.pdf}, booktitle={20nd International Symposium on Plasma Chemistry (ISPC-20), Philadelphia, Pennsylvania, USA, 2011}, author={Lackmann, Jan-Wilm and Stapelmann, Katharina and Narberhaus, Franz and Awakowicz, Peter and Bandow, Julia E}, year={2011} }
 @article{kylián_rauscher_ruiz_denis_stapelmann_rossi_2010, title={Elimination of Pathogenic Biological Residuals by Means of Low-Pressure Inductively Coupled Plasma Discharge}, volume={3}, ISBN={9783527325443}, url={https://publons.com/wos-op/publon/15867444/}, DOI={10.1002/9783527629749.ch15}, abstractNote={This chapter contains sections titled: Introduction Experimental Results Conclusions Acknowledgments References}, journal={Industrial Plasma Technology}, publisher={Wiley-Blackwell}, author={Kylián, Ondřej and Rauscher, Hubert and Ruiz, Ana and Denis, Benjamin and Stapelmann, Katharina and Rossi, François}, editor={Y. Kawai, H. Ikegami and N. Sato, A. Matsuda and K. Uchino, M. Kuzuya and Mizuno, A.Editors}, year={2010}, month={Mar}, pages={193–199} }
 @article{keudell_awakowicz_benedikt_raballand_yanguas-gil_opretzka_floetgen_reuter_byelykh_halfmann_et al._2010, title={Inactivation of Bacteria and Biomolecules by Low-Pressure Plasma Discharges}, volume={7}, ISSN={["1612-8869"]}, url={http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=ORCID&SrcApp=OrcidOrg&DestLinkType=FullRecord&DestApp=WOS_CPL&KeyUT=WOS:000276547700018&KeyUID=WOS:000276547700018}, DOI={10.1002/ppap.200900121}, abstractNote={The inactivation of bacteria and biomolecules using plasma discharges were investigated within the European project BIODECON. The goal of the project was to identify and isolate inactivation mechanisms by combining dedicated beam experiments with especially designed plasma reactors. The plasma reactors are based on a fully computer-controlled, low-pressure inductively-coupled plasma (ICP). Four of these reactors were built and distributed among the consortium, thereby ensuring comparability of the results between the teams. Based on this combinedeffort,theroleofUVlight,ofchemicalsputtering(i.e.thecombinedimpactofneutrals and ions), and of thermal effects on bacteria such as Bacillus atrophaeus, Aspergillus niger ,a s well as on biomolecules such as LPS, Lipid A, BSA and prions have been evaluated. The particle fluxes emerging from the plasmas are quantified by using mass spectrometry, Langmuir probe measurements, retarding field measurements and optical emission spectroscopy. The effects of the plasma onthe biologicalsystems are evaluatedusingatomic force microscopy, ellipsometry, electrophoresis, specially-designed western blot tests, and animal models. A quantitative analysis of the plasma discharges and the thorough study of their effect on biological systems led to the identification of the different mechanisms operating during the decontamination process.OurresultsconfirmtheroleofUVinthe200‐250nmrangefortheinactivationofmicroorganisms and a large variability of results observed between different strains of the same species. Moreover, we also demonstrate the role of chemical sputtering corresponding to the synergism between ion bombardment of a surface with the simultaneous reaction of active species such as O, O2 or H. Finally, we show that plasma processes can be efficient against different micro-organisms, bacteria and fungi, pyrogens, model proteins and prions. The effect of matrices is described, and consequences for any future industrial implementation are discussed.}, number={3-4}, journal={PLASMA PROCESSES AND POLYMERS}, publisher={Wiley-Blackwell}, author={Keudell, A. and Awakowicz, P. and Benedikt, J. and Raballand, V. and Yanguas-Gil, A. and Opretzka, J. and Floetgen, C. and Reuter, R. and Byelykh, L. and Halfmann, H. and et al.}, year={2010}, month={Mar}, pages={327–352} }
 @inproceedings{stapelmann_bibinov_denis_semmler_awakowicz_2010, title={Sterilization and surface decontamination by a novel VHF-CCP}, url={http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=ORCID&SrcApp=OrcidOrg&DestLinkType=FullRecord&DestApp=INSPEC&KeyUT=INSPEC:11486060&KeyUID=INSPEC:11486060}, DOI={10.1109/plasma.2010.5534056}, abstractNote={Summary form only given. The application of low pressure plasma discharges for sterilization of medical instruments is an upcoming alternative to common sterilization methods, due to the variety of drawbacks, e.g. high temperature, toxic chemical agents, or the inability to sterilize and remove pathogenic material, commonly used methods are associated with. Plasma sterilization offers a highly effective, low temperature sterilization and decontamination process with a reduced process time.The capabilities of plasma treatment have been demonstrated in several laboratory setups1"3. Based on these experiences, a novel setup has been developed. It is realized as capacitively coupled plasma discharge powered by an oscillator power source in the variable frequency range between 76 and 80 MHz. The setup is designed to meet industrial needs. The discharge chamber is shaped like a drawer and composed of PEEK, a high-performance plastic. This leads to an easy handling sterilization process uncomplicated for application. Optical emission spectroscopy was performed to obtain detailed information about the plasma parameters and to optimize the plasma for sterilization purpose. Microbiological tests as well as protein removal tests are going to be presented.}, booktitle={2010 Abstracts IEEE International Conference on Plasma Science}, publisher={Institute of Electrical & Electronics Engineers (IEEE)}, author={Stapelmann, Katharina and Bibinov, Nikita and Denis, Benjamin and Semmler, Egmont and Awakowicz, Peter}, year={2010}, month={Jun}, pages={1 pp.} }
 @inproceedings{stapelmann_bibinov_awakowicz_wunderlich_2009, title={Characterization of a new VHF-CCP for sterilization}, url={https://meetings.aps.org/Meeting/GEC09/Session/SR1.4}, booktitle={62nd Annual Gaseous Electronics Conference}, author={Stapelmann, Katharina and Bibinov, Nikita and Awakowicz, Peter and Wunderlich, Joachim}, year={2009} }
 @article{stapelmann_bibinov_awakowicz_2009, title={Development and characterization of a new VHF-CCP for sterilization}, journal={ISPC 19 Proceedings}, author={Stapelmann, Katharina and Bibinov, Nikita and Awakowicz, Peter}, year={2009} }
 @article{rauscher_stapelmann_kylian_denis_rossi_2009, title={Monitoring plasma etching of biomolecules by imaging ellipsometry}, volume={84}, ISSN={["0042-207X"]}, url={http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=ORCID&SrcApp=OrcidOrg&DestLinkType=FullRecord&DestApp=WOS_CPL&KeyUT=WOS:000270625900018&KeyUID=WOS:000270625900018}, DOI={10.1016/j.vacuum.2009.05.012}, abstractNote={Low-pressure plasma discharges can be applied to remove various biomolecules from surfaces. However, the knowledge on the interaction between plasma and biomolecules and the kinetics of their removal is still rather poor, which is a major limiting factor for the optimization of this type of plasma treatment. This is, among other reasons, because of the restrictions of currently used techniques for the evaluation of the rates of biomolecule removal during plasma treatment. Therefore, an alternative method based on imaging ellipsometry is applied in this study. It is shown that this method allows reliable semi-quantitative comparison of the treatment efficiency of plasma discharges sustained in different gas mixtures.}, number={1}, journal={VACUUM}, publisher={Elsevier BV}, author={Rauscher, H. and Stapelmann, K. and Kylian, O. and Denis, B. and Rossi, F.}, year={2009}, month={Aug}, pages={75–78} }
 @article{stapelmann_kylian_denis_rossi_2008, title={On the application of inductively coupled plasma discharges sustained in Ar/O(2)/N(2) ternary mixture for sterilization and decontamination of medical instruments}, volume={41}, ISSN={["0022-3727"]}, url={http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=ORCID&SrcApp=OrcidOrg&DestLinkType=FullRecord&DestApp=WOS_CPL&KeyUT=WOS:000259441800006&KeyUID=WOS:000259441800006}, DOI={10.1088/0022-3727/41/19/192005}, abstractNote={Non-equilibrium low pressure-plasma discharges are extensively studied for their high potential in the field of sterilization and decontamination of medical devices. This increased interest in plasma discharges arises from, among other reasons, their capability not only to inactivate bacterial spores but also to eliminate, destroy or remove pathogenic biomolecules and thus to provide a one-step process assuring safety of treated instruments. However, recent studies have shown that optimal conditions leading to inactivation of spores and physical removal of pathogens differ significantly—the efficiency of spores sterilization is above all dependent on the UV radiation intensity, whereas high etching rates are connected with the presence of the etching agent, typically atomic oxygen. The aim of this contribution is to discuss and demonstrate the feasibility of Ar/N2/O2 low-pressure inductively coupled plasma discharges as an option to provide intense UV radiation while maintaining the high etching rates of biomolecules.}, number={19}, journal={JOURNAL OF PHYSICS D-APPLIED PHYSICS}, publisher={IOP Publishing}, author={Stapelmann, K. and Kylian, O. and Denis, B. and Rossi, F.}, year={2008}, month={Oct} }
 @inproceedings{kylian_stapelmann_rauscher_rossi_2008, title={On the use of imaging ellipsometry for the monitoring of protein removal by means of low-pressure inductively coupled plasma discharges}, url={http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=ORCID&SrcApp=OrcidOrg&DestLinkType=FullRecord&DestApp=INSPEC&KeyUT=INSPEC:10154328&KeyUID=INSPEC:10154328}, DOI={10.1109/plasma.2008.4590743}, abstractNote={Summary form only given. Non-equilibrium plasma discharges have been recently proposed to be an effective tool for the removal of protein residues from the surfaces of medical instruments and devices. However, the knowledge regarding plasma-protein interactions is still relatively poor, which consequently represents a serious drawback for the validation of this technique as well as for the optimization of the treatment. This is, among other reasons, caused by the limitations of currently used techniques for the determination of the rates of protein removal during plasma treatment. The methods used are either restricted to a narrow range of substrate materials (e.g. in the cases of quartz crystal microbalance or surface plasmon resonance) or due to their high surface sensitivities (e.g. in the case of XPS or ToF-SIMS) the thickness of the deposit is limited to few tens of nm. The objective of this contribution is therefore to present an alternative method to evaluate the efficiency of protein removal. This technique is based on imaging ellipsometry, namely on the monitoring of the temporal evolution of a 2D representation of the values of the Delta and psi angles. As it will be shown this approach allows fast and semi-quantitative monitoring of the process and thus it enables to compare capabilities of plasma discharges sustained under different experimental conditions to remove protein coatings. This will be demonstrated on deposits of a model protein (bovine serum albumin) treated by low-pressure inductively coupled plasma discharges sustained in argon based mixtures. Moreover, the results are going to be compared with the results of other diagnostics techniques.}, booktitle={2008 IEEE 35th International Conference on Plasma Science}, publisher={Institute of Electrical & Electronics Engineers (IEEE)}, author={Kylian, Ondrej and Stapelmann, Katharina and Rauscher, Hubert and Rossi, Francois}, year={2008}, month={Jun}, pages={1 pp.} }
 @inproceedings{kylian_stapelmann_rossi_2008, title={Sterilization and decontamination of medical instruments by low pressure plasma discharges: Application of ternary mixtures}, url={https://publons.com/wos-op/publon/15867445/}, DOI={10.1109/plasma.2008.4590770}, abstractNote={Summary form only given. Application of non-equilibrium plasma discharges for sterilization of medical instruments appeared to be promising alternative to commonly used sterilization techniques. This is due to advantageous and unique properties of plasma discharges allowing highly effective treatment without necessity to use toxic substances and maintaining low temperature conditions favorable for treatment of heat degradable articles. Moreover, it was already demonstrated among others by our group that the low-pressure plasma discharges are capable not only to kill bacteria and bacterial spores, but also to remove or inactivate various pathogenic biomolecules such as bacterial endotoxins1'2 or proteins2. However, optimal conditions leading to surface sterilization and decontamination differ significantly, owing to the different pathways leading to the desired effect. According to the results obtained using low pressure plasma discharges, the efficiency of sterilization of bacterial spores is typically linked with the intensity of UV radiation emitted by the plasma discharge. The intense UV emission in the spectral range optimal for the spores killing is commonly achieved using oxygen-nitrogen discharge mixture. Nevertheless, this mixture was found to be inefficient for the fast elimination or removal of biomolecules. The different discharge mixtures needed for sterilization and physical removal of biological substances has important consequences for the optimization of the treatment in the case of a real situation when the requirement is to guarantee both sterility and complete elimination of pathogens. This implies either application of two step plasma treatment -the first step favoring killing of spores and the second physical removal of pathogens-, or, as it will be demonstrated in this contribution by utilization of ternary discharge mixtures that allow to optimize both UV intensity and removal rate of biomolecules.}, booktitle={2008 IEEE 35th International Conference on Plasma Science}, publisher={Institute of Electrical & Electronics Engineers (IEEE)}, author={Kylian, Ondrej and Stapelmann, Katharina and Rossi, Francois}, year={2008}, month={Jun} }