The 2nd Workshop on Biological Applications of Plasma/Photon Processing


Abstracts

Sterilization of medical equipments using oxygen RF plasma
Nobuya Hayashi
Saga University
Sterilization of medical equipments is performed using a low pressure RF inductively coupled plasma. Oxygen radicals and atomic oxygen as oxidizing agents are produced from oxygen or water vapor. The pressure in the treatment chamber is varied periodically during the sterilization in order to penetrate the produced radicals into tiny gaps of medical equipment. Medium sheets for microbial detection indicated that the decimal reduction values of active bacillus were 21 minutes and 26 minutes using oxygen and water vapor, respectively with the RF power of 60 W. The sterilization of bacilli spore in the AAMI (Association for the Advancement of Medical Instrumentation) routine PCD is successful for the treatment time of 180 minutes. Also, removal of proteins on the surface of medical equipment is attempted using oxygen plasma.




Computational design, organic chemical synthesis, and biological assay of an inhibitor against HIV-1 protease
Tyuji Hoshino
Graduate School of Pharmaceutical Sciences, Chiba University
Inhibitors against human immunodeficiency virus type-1 (HIV-1) proteases are effective for anti-HIV-1 treatments. However, the therapeutic efficacy is reduced by the rapid emergence of inhibitor-resistant variants of the protease. Among patients who failed in the treatment with approved inhibitors, L90M mutation of HIV-1 protease is often observed. The aim of this study is to provide new drugs having keen efficacy against not the wild-type but the L90M mutant of HIV-1 protease. First, we analyzed why the L90M mutation causes the decrease of the therapeutic efficacy of the approved inhibitors, performing molecular dynamics simulation on the complex of HIV-1 protease and inhibitors. Second, dozens of chemical structures supposed to be effective for the L90M mutant were proposed by close inspection of atom geometry at the reaction pocket of the protease and, then, the most promising structure was selected as a newly designed drug through the computer simulations for the complexes of L90M mutant of HIV-1 protease and many proposed candidates. Third, the designed chemical compound has been synthesized by the organic chemical experiments. Finally, the efficacy of the synthesized chemical has be measured with the isothermal titration calorimetry and the in vitro cell assay.


Biodevices and related plasma technologies
Takanori Ichiki
Department of Bioengineering, School of Engineering & Center for NanoBio Integration,
The University of Tokyo
Our research aims to create nanobio analytical systems through the development of highly functional biochips using nano/microfabrication technologies and their combination with microscopic imaging apparatus. Novel microreactor and/or microfluidic devices with micro/nanostructures are going to be designed so as to enable direct manipulation and precise measurement of individual cells and biomolecules. This research is expected to provide fundamental tools for biological function analysis and will have great influence in the field of biotechnology research, clinical test and drug screening. I will present how we take advantages of some plasma application technologies such as precise etching and patterned surface treatment in R&D of biodevices.


Plasma sterilization in aqueous environment
Satoshi Ikawa 1), Katsuhisa Kitano 2) and Satoshi Hamaguchi 2)
1)Technology Research Institute of Osaka Prefecture
2)Center for Atomic and Molecular Technologies, Graduate School of Engineering, Osaka University
Nonequilibrium atmospheric pressure plasma supplies high-energy active species that potentially contribute to various chemical reactions. Especially, the plasma jet generation system with low-frequency pulses (LF jet) is an available tool for plasma processes in aqueous solutions, which provides novel reaction systems. In this work, LF jet system has been applied for sterilization in aqueous environment.
In order to estimate bactericidal activity in aqueous solutions, LF jet was generated to be in contact with the solutions containing bacteria. This resulted in complete bacteria inactivation in short period (~ 2 min). Bactericidal activity by LF jet exposure reduced drastically by addition of superoxide dismutase, whereas not affected by increase of nitrogen oxide ions and hydrogen peroxide. Moreover, plasma discharge in low-oxygen atmosphere inside chamber system also resulted in the decrement of bactericidal activity. These facts suggest that oxygen radicals such as superoxide anion play a large part in bactericidal activity in aqueous environment.

Biological application of THz wave
Hideaki Kitahara
Institute of Laser Engineering, Osaka Univerity
The electromagnetic wave between the radio wave region and the infrared region is called Terahertz (THz) wave. THz-wave is attracting public attention because of its harmless property on biological material as compared to X-ray. For example, many researchers are investigating biochemical materials, the quality control in drug production, and medical diagnosis. At present, the most general analysis method in the THz region is THz time-domain spectroscopy (THz-TDS). We constructed several kinds of THz-TDS systems for the analysis and diagnosis of biological samples. Several observations were made using these systems. For example, the coating analysis of a medicine pill and the diagnosis of a pathological sample were made. Moreover, a basic device for medical equipment application was also made. In the presentation, the detail of our study will be reported and discussed.


Development of NIR Bioimaging Systems Based on “Atomic Technologies” throughout “Polyscale” Technologies
Kohei Soga
Polyscale Technology Research Center, Tokyo University of Science, Chiba, Japan
Department of Materials Science and Technology, Tokyo University of Science
Fluorescence bioimaging (FBI) is one of the most important technologies for the biomedical field of researches. In most cases, fluorescent proteins or organic dyes are used as fluorescence sources, which require the ultraviolet (UV) or visible (VIS) excitation source. Serious problems of the current FBI system are the color fading of the fluorescent probes and damage to the biological substances due to the phototoxicity of the high photon energy of the excitation light. The development of the FBI system with both near infrared (NIR) excitation and emission should thus deliver a system without phototoxicity on probes themselves and biological substances as a result of the low photon energy of the NIR light. Rare-earth doped ceramic phosphors (RED-CNP) are known fluorescent materials in NIR region under an NIR excitation. The key issues for developing the NIR-FBI system are the design and fabrication size-controlled and highly emissive RED-CNP, surface modification of the RED-CNP with a biofunctional polymer and the development of an imaging system with NIR excitation and detection, such as biological microscopes or in-vivo imaging system. The development of the NIR-FBI system is going on by the “polyscale technology” starts from an atomic scale technology into macroscopic technologies through nanotechnologies.


The influence of cold atmospheric plasma on cell cycle and apoptosis
E. Stoffels, J.L.V. Broers
Department of Biomedical Engineering, Eindhoven University of Technology,
PO Box 513, 5600 MB Eindhoven, The Netherlands.
Non-inflammatory growth suppression of tissues can be achieved by controlled induction of programmed cell death (apoptosis), or by suppressing cell proliferation in other way, but without inflicting accidental cell death (necrosis). Our previous works showed that treatment with cold atmospheric plasma usually did not induce necrosis, but triggered sub-lethal cell reactions (detachment, apoptosis) in various cell types. In this work we quantitatively resolve the influence of plasma treatment on cell cycle and apoptotic behaviour. We use several types of cells (vascular, epithelial, etc.) and perform flow cytometric analysis of their DNA profiles. We clearly observe dose-dependent influences on cell proliferation: this can be either suppressed or enhanced by plasma, dependent on the dosage. Apoptosis is abundant, but it manifests itself 48-72 h after treatment, which is rather long compared to the cell cycle. We argue that our type of apoptotic trigger is different from the commonly known ones (e.g. apoptosis induced by DNA damage). A tentative explanation will be proposed.


Laser induced self-assembly of molecules and nanoparticles by using
optical radiation pressure
Hiroyuki Yoshikawa
Graduate School of Engineering, Osaka Univ.
By tightly focusing a nonresonant laser beam in molecular solution or nanoparticle suspension, Brownian motion is restricted and local concentration increases in the laser focus due to optical radiation pressure (gradient force). This effect is expected to lead to laser induced self-assembly (LAISA) of molecules and nanoparticles. One of the characteristics of LAISA is the formation of microstructures possessing high optical functionalities due to dipole-dipole interaction between nanoparticles (molecules) under the focused laser beam. J-aggregates of pseudoisocyanine dye and metallic nanoparticles show characteristic optical and spectroscopic properties in the laser focus, suggesting LAISA effect. Applications to molecular spectroscopy and bio-sensing of LAISA are also introduced in this talk.