Bulletin of the American Physical Society
62nd Annual Gaseous Electronics Conference
Volume 54, Number 12
Tuesday–Friday, October 20–23, 2009; Saratoga Springs, New York
Session RR1: Biological and Emerging Applications of Plasma I |
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Chair: Deborah O'Connell, Queen's University Belfast Room: Saratoga Hilton Ballroom 1 |
Thursday, October 22, 2009 8:00AM - 8:15AM |
RR1.00001: Atmospheric pressure generation of singlet oxygen by arrays of microplasmas for DNA oxidation Joao Santos Sousa, Gerard Bauville, Bernard Lacour, Vincent Puech, Michel Touzeau, Jean-Luc Ravanat Recently, we demonstrated [1] that Micro-Cathode Sustained Discharges (MCSD) can be very effective for producing large amounts of O$_{2}$(a$^{1}\Delta )$ at atmospheric pressure. In the present work, we show that O$_{2}$(a$^{1}\Delta )$ densities higher than 3 10$^{16}$ cm$^{-3}$ can be produced by arrays of MCSD operating at atmospheric pressure in He/O$_{2}$/NO mixtures, resulting in O$_{2}$(a$^{1}\Delta )$ fluxes above 30 mmol/h. The effect of different parameters such as gas flows and mixtures, discharge current and array geometry are discussed. Arrays of MCSD, allowing the production at atmospheric pressure of O$_{2}$(a$^{1}\Delta )$ and O$_{3}$ densities between 10$^{13}$ and 10$^{16}$ cm$^{-3}$, with an easily tunable ratio, appear to be very useful tools to study in details the reactivity of these reactive oxygen species with DNA constituents. Experiments were conducted showing that Adenine, Thymine and Cytosine constituents are effectively oxidized by O$_{3}$, while O$_{2}$(a$^{1}\Delta )$ only reacts with 2'-deoxyguanosine (dGuo). A more detailed study on the reactivity of O$_{2}$(a$^{1}\Delta )$ and O$_{3}$ with aqueous DNA solutions is in progress. [1] J.S. Sousa et al., Appl. Phys. Lett. \textbf{93}, 011502 (2008) [Preview Abstract] |
Thursday, October 22, 2009 8:15AM - 8:30AM |
RR1.00002: Role of Plasma Discharge in Division of Prostatic Tissue Arlen Ward, Carl Almgren, Zeng-Qi Yu, Joe Sartor, George Collins During the treatment of benign prostatic hyperplasia electrical energy is used to separate prostatic tissue and remove it as a urinary obstruction. This surgical procedure is often performed in a saline environment, and current paths change as the tissue and fluid are heated. This study shows that a plasma discharge at the electrode is necessary to provide the current densities necessary to vaporize portions of the prostatic tissue in order to facilitate removal. This behavior is predicted in finite element simulations, and verified with color schlieren imaging and ex vivo bovine prostate tests. [Preview Abstract] |
Thursday, October 22, 2009 8:30AM - 8:45AM |
RR1.00003: Plasma-Chemical Removal of Tissue Cameron Moore, Il Gyo Koo, George Collins We report the use of plasma generated chemical species to affect a strong enhancement in removal of ex vivo tissue. The data show a demonstrable, perhaps predominant, chemical component which contributes to tissue removal. Effects expected from purely thermal processes are also observed to be limited. These initial studies have also shown the ability to create high aspect ratio regions of removed tissue, indicative of a directional process. [Preview Abstract] |
Thursday, October 22, 2009 8:45AM - 9:00AM |
RR1.00004: Mechanism for Ring-Opening of Aromatic Polymers by Remote Atmospheric Pressure Plasma Eleazar Gonzalez, Michael Barankin, Peter Guschl, Robert Hicks A low-temperature, atmospheric pressure oxygen and helium plasma was used to treat the surfaces of polyetheretherketone, polyphenylsulfone, polyethersulfone, and polysulfone. These aromatic polymers were exposed to the afterglow of the plasma, which contained oxygen atoms, and to a lesser extent metastable oxygen ($^{1}\Delta _{g}$ O$_{2})$ and ozone. After less than 2.5 seconds treatment, the polymers were converted from a hydrophobic state with a water contact angle of 85$\pm $5\r{ } to a hydrophilic state with a water contact angle of 13$\pm $5\r{ }. It was found that plasma activation increased the bond strength to adhesives by as much as 4 times. X-ray photoelectron spectroscopy revealed that between 7{\%} and 27{\%} of the aromatic carbon atoms on the polymer surfaces was oxidized and converted into aldehyde and carboxylic acid groups. Analysis of polyethersulfone by internal reflection infrared spectroscopy showed that a fraction of the aromatic carbon atoms were transformed into C=C double bonds, ketones, and carboxylic acids after plasma exposure. It was concluded that the oxygen atoms generated by the atmospheric pressure plasma insert into the double bonds on the aromatic rings, forming a 3-member epoxy ring, which subsequently undergoes ring opening and oxidation to yield an aldehyde and a carboxylic acid group. [Preview Abstract] |
Thursday, October 22, 2009 9:00AM - 9:30AM |
RR1.00005: Measuring DNA through a Nanopore Fabricated Using Plasma Processing Technology Invited Speaker: We have been developing a device based on a 2-3 nm diameter pore between two electrolyte volumes for the transit of DNA by means of a potential gradient. The nanopore is configured with 3 electrodes, each about 3 nm thick with 2-3nm dielectric spacers. The nanopore electrodes can be used to trap DNA in-transit, and ideally measure the impedance and hence the identity of each nucleotide as it passes through the nanopore, allowing real time sequencing of the DNA. The goal is to operate at megahertz, allowing sequencing of the entire genome within a few hours a fairly modest cost. This project has lead to numerous new developments in nanoscale fabrication, particularly for nanofluidics. The nanopore devices are fabricated using a number of critical plasma processing steps, both deposition and etch, in our 200mm pilot facility. [Preview Abstract] |
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