Bulletin of the American Physical Society
61st Annual Gaseous Electronics Conference
Volume 53, Number 10
Monday–Friday, October 13–17, 2008; Dallas, Texas
Session DT2: Biological and Emerging Applications of Plasma |
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Chair: E. Stoffels, Eindhoven University of Technology/Drexel University Philadelphia Room: Salon A-D |
Tuesday, October 14, 2008 1:30PM - 1:45PM |
DT2.00001: GEC Student Award for Excellence Finalist: Atmospheric pressure generation of high fluxes of singlet oxygen for biological applications J. Santos Sousa, G. Bauville, B. Lacour, V. Puech, M. Touzeau, J.L. Ravanat The generation of singlet oxygen states, O2(a1D), by microplasmas has been studied experimentally. For binary He/O2 mixtures, we previously reported that O2(a1D) densities of about 10$^{15}$ cm$^{-3}$ can be efficiently achieved at atmospheric pressure in a 3-electrode microcathode sustained discharge (MCSD) configuration[1]. One solution to increase the O2(a1D) number density is to add, in the He/O$_{2}$ mixture, an O-atom scavenger in order to reduce the quenching processes. Thus, we have studied the influence of adding small concentrations of NO molecules. We report experimental results showing that, in He/O$_{2}$/NO mixtures and at atmospheric pressure, O2(a1D) number densities higher than 10$^{16 }$cm$^{-3}$ were measured in the MCSD afterglow at total flow rates up to 30 ln/min, resulting in O2(a1D) fluxes above 10 mmol/h. This opens opportunities for a large spectrum of new applications. Preliminary experiments were conducted showing that the developed system is particularly useful to study in details the reactivity of singlet oxygen with biological molecules such as DNA constituents. [1] G. Bauville et al., AIAA paper 2007-4025 [Preview Abstract] |
Tuesday, October 14, 2008 1:45PM - 2:00PM |
DT2.00002: Investigation of Cell Surfaces using Microplasma-Assisted Desorption/Ionization Mass Spectroscopy Joshua Symonds, Lan Sun, Facundo Fern\'andez, Thomas Orlando Low-temperature, atmospheric pressure microplasmas have been developed for a wide array of uses. We have investigated one type of these devices, a Microhollow Cathode Discharge (MHCD) for desorbing and ionizing samples to be analyzed with standard mass spectroscopy techniques. Our work includes the development and use of MHCD's to analyze solid and liquid phase samples, with particular attention given to biologically-relevant substances. The goal of this line of research is to investigate, without causing undue fragmentation, the compounds present on and within cell membranes. By varying the properties of the plasma, including electron temperature, plasma density, and the plasma's interactions with the sample, we seek to investigate the role of different plasma components in the desorption/ionization events. Specifically, we seek to determine whether the process is dominated by emitted electrons, high energy (VUV) photons, metastable particles, or a combination thereof. [Preview Abstract] |
Tuesday, October 14, 2008 2:00PM - 2:30PM |
DT2.00003: Interaction of Low Temperature Plasmas with Prokaryotic and Eukaryotic Cells Invited Speaker: Due to promising possibilities for their use in medical applications such as wound healing, surface modification of biocompatible materials, and the sterilization of reusable heat-sensitive medical instruments, low temperature plasmas and plasma jets are making big strides as a technology that can potentially be used in medicine$^{1-2}$. At this stage of research, fundamental questions about the effects of plasma on prokaryotic and eukaryotic cells are still not completely answered. An in-depth understanding of the pathway whereby cold plasma interact with biological cells is necessary before real applications can emerge. In this paper, first an overview of non-equilibrium plasma sources (both low and high pressures) will be presented. Secondly, the effects of plasma on bacterial cells will be discussed. Here, the roles of the various plasma agents in the inactivation process will be outlined. In particular, the effects of UV and that of various reactive species (O$_{3}$, O, OH{\ldots}) are highlighted. Thirdly, preliminary findings on the effects of plasma on few types of eukaryotic cells will be presented. How plasma affects eukaryotic cells, such as mammalian cells, is very important in applications where the viability/preservation of the cells could be an issue (such as in wound treatment). Another interesting aspect is the triggering of apoptosis (programmed cell death). Some investigators have claimed that plasma is able to induce apoptosis in some types of cancer cells. If successfully replicated, this can open up a novel method of cancer treatment. In this talk however, I will briefly focus more on the wound healing potential of cold plasmas. \newline \newline $^1$E. A. Blakely, K. A. Bjornstad, J. E. Galvin, O. R. Monteiro, and I. G. Brown, ``Selective Neuron Growth on Ion Implanted and Plasma Deposited Surfaces'', \textit{In Proc. IEEE Int. Conf. Plasma Sci}., (2002), p. 253. \newline $^2$M. Laroussi, ``Non-thermal Decontamination of Biological Media by Atmospheric Pressure Plasmas: Review, Analysis, and Prospects'', \textit{IEEE Trans. Plasma Sci}., Vol. 30, No. 4, pp. 1409-1415, (2002). [Preview Abstract] |
Tuesday, October 14, 2008 2:30PM - 2:45PM |
DT2.00004: GEC Student Award for Excellence Finalist: Interaction of Non-Thermal Dielectric Barrier Discharge Plasma with DNA inside Cells Sameer Kalghatgi, Crystal Kelly, Gregory Fridman, Jane Clifford-AzizKhan, Alexander Fridman, Gary Friedman Direct non-thermal plasma is now being widely considered for various medical applications, viz; cancer treatment, coagulation, wound healing. However, the understanding of the interaction between non-thermal plasma and cells is lacking. Here we study the possibility that effects of the plasma treatment can penetrate though cellular membranes without destroying them. One of the most important of such effects to investigate would be DNA double strand breaks (DSB's) since these are some of the important events in a cell's life cycle. We measured DNA DSB's in mammalian cells using immunofluorescence and western blots. Hydrogen peroxide treatment was used as a positive control since it is known to induce massive DNA double strand breaks. The results indicate that short (5 seconds) direct plasma treatment at low power (0.2 W/cm$^{2})$ does produce DNA DSB's in mammalian cells. This means that somehow plasma penetrates inside the cells. Several questions arise about what is the mechanism of penetration and do the cells repair the DNA DSB's. We show that the cells do repair the DNA DSB's produced by short exposure of low power plasma. Although the detailed mechanisms are being investigated we confirmed that reactive oxygen species mediate interaction between plasma and DNA. [Preview Abstract] |
Tuesday, October 14, 2008 2:45PM - 3:00PM |
DT2.00005: Characteristics of atmospheric pressure air micro slot plasma and application to bacterial inactivation Il Gyo Koo, Jin Hoon Cho, Woong Moo Lee, Cameron Moore, George Collins The E-coli was inactivated using an atmospheric pressure microplasma in air. The microplasma was generated between two parallel aluminum rods are 5 cm long, 3 mm in diameter, maintain 200 $\mu $m wide gaps between two electrodes, and covered with nanoporous alumina films $^{1,2}$. The 20 kHz AC driven discharge is generated between two parallel rods. The plasma gas temperature was measured by emission spectroscopy and FT-IR camera, which is so closed at room temperature. The E-coli sample placed between the two electrodes underwent chemical and physical treat on E-coli sample during the discharge. Experimental results demonstrated a colony forming unit reduction from 10$^{7}$ to 10$^{5}$ within 10 minutes treatment. [Preview Abstract] |
Tuesday, October 14, 2008 3:00PM - 3:15PM |
DT2.00006: Finite element analysis of the plasma needle-biomaterial interaction at atmospheric pressure Yukinori Sakiyama, David Graves The atmospheric pressure RF-excited plasma needle is a non-thermal discharge sustained at the sharp tip of a needle in helium gas flow. The plasma needle has been applied to various biomedical applications. However, the mechanisms of the plasma-biomaterial interaction are only poorly understood. In this study, we focus on influences of humid air diffusing into the discharge domain on plasma chemistry. Our fluid model includes 49 species and over 700 elementary reactions in one-dimensional spherical coordinates. An expected concentration gradient of humid air is assumed to be present due to back diffusion of air against helium convective flow. Our simulation results indicate that O2+ and N2+ are dominant ions at the outer electrode corresponding to the biomaterial surface and that the most abundant neutrals near the outer electrode are O, O2*, and OH radicals. These results suggest that trace amounts of humid air can play a central role in plasma needle treatment. [Preview Abstract] |
Tuesday, October 14, 2008 3:15PM - 3:30PM |
DT2.00007: Cold atmospheric air plasma jet for medical applications Juergen F. Kolb, Robert O. Price, Michael Stacey, R. James Swanson, Angela Bowman, Robert L. Chiavarini, Karl H. Schoenbach By flowing ambient air through the discharge channel of a microhollow cathode geometry, we were able to sustain a stable 1.5-2~cm long afterglow plasma jet with dc voltages of only a few hundred volts. The temperature in this expelled afterglow plasma is close to room temperature. Emission spectra show atomic oxygen, hydroxyl ions and various nitrogen compounds. The low heavy-particle temperature allows us to use this exhaust stream on biological samples and tissues without thermal damage. The high levels of reactive species suggest an effective treatment for pathological skin conditions caused, in particular, by infectious agents. In first experiments, we have successfully tested the efficacy on \textit{Candida kefyr} (a yeast), \textit{E.coli,} and a matching \textit{E.coli} strain-specific virus. All pathogens investigated responded well to the treatment. In the yeast case, complete eradication of the organism in the treated area could be achieved with an exposure of 90 seconds at a distance of 5~mm. A 10-fold increase of exposure, to 900 seconds caused no observable damage to murine integument. [Preview Abstract] |
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