| AVS 59th Annual International Symposium and Exhibition | |
| Plasma Science and Technology | Monday Sessions |
| Session PS+BI-MoA |
| Session: | Applications of (Multiphase) Atmospheric Plasmas (including Medicine and Biological Applications) |
| Presenter: | T.-Y. Chung, University of California Berkeley |
| Authors: | T.-Y. Chung, University of California Berkeley J.-W. Chu, University of California Berkeley D.B. Graves, University of California Berkeley E. Bartis, University of Maryland J. Seog, University of Maryland G.S. Oehrlein, University of Maryland |
| Correspondent: | Click to Email |
Effective removal of infectious organisms and/or biomolecules from medical instruments is essential to prevent infections and disease transmission. Intricate modern instruments are difficult to clean via thermal sterilization since they are often heat sensitive. Furthermore, bacterial endotoxin and prion proteins are known to be particularly resistant to conventional sterilization procedures.[1, 2] Low-temperature plasma is a promising option for surface sterilization of bacteria and deactivation of harmful biomolecules, but mechanisms of endotoxic biomolecule deactivation are poorly understood.[3] Using a vacuum beam system, we study the effects of vacuum ultraviolet (VUV) radiation, oxygen and deuterium radicals on lipid A, the immune-stimulating region of lipopolysaccharide (LPS). The endotoxic activity of lipid A samples is monitored by measuring the secreted interleukin-1β (IL-1β) in human whole blood. The results obtained from ex situ transmission Fourier transform infrared (FTIR) spectroscopy, in situ quartz crystal microbalance (QCM), in situ residual gas analysis and ex situ electrospray ionization mass spectrometry (ESI-MS) show that VUV photons cause bulk modification to the penetration depth of photons, ~200 nm. On the other hand, radicals mainly cause chemical etching and modification near the surface of lipid A films. Although the radical-induced etch yield of lipid A is much lower than VUV-induced photolysis, secondary ion mass spectrometry (SIMS) and human whole blood-based assay demonstrate that O and D radicals alter the film surface, leading to significant reduction of film endotoxicity. Important structures governing the endotoxic activity of lipid A, e.g. the fatty acid chains and the phosphate groups, are greatly reduced after radical exposure. Qualitatively similar results are observed when LPS films are exposed to either H atoms or VUV photons in low-pressure plasma. The deactivation effects of low energy ions and atmospheric pressure air plasma on lipid A films will also be presented.
[1] K. L. Williams, ed., Endotoxins: Pyrogens, LAL Testing and Depyrogenation, Informa Healthcare USA, Inc., New York, 2007.
[2] W. A. Rutala and D. J. Weber, Infect. Control Hosp. Epidemiol. 31, 107 (2010)
[3] A. von Keudell et al., Plasma Process. Polym. 7, 327 (2010)