Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
5369523 | Applied Surface Science | 2008 | 7 Pages |
The distribution of electrons, ions and oxygen radicals in long-distance oxygen plasma and the germicidal effect (GE) of Escherichia coli on the surface of medical poly(tetrafluoroethylene) (PTFE) film were studied. The quantity of protein leakage and the production of lipid peroxide in bacterial suspension as well as the state of DNA were measured after sterilization to analyse the inactivation mechanisms. The results showed that the concentration of electrons and ions decreased rapidly with increasing the distance from the center of induction coil, which approximated to 0 at 30Â cm, whereas the concentration of oxygen radicals reduced slowly, i.e. decreased 30% within 40Â cm. GE value reached 3.42 in the active discharge zone (0Â cm) and exceeded 3.32 within 40Â cm when plasma treatment parameters were set as follows: plasma rf power at 100Â W, treatment time at 60Â s and oxygen flux at 40Â cm3/min. Fast etching action on cell membrane by electrons, ions and attacking polyunsaturation fatty acid (PUFA) in cell membrane by oxygen radicals are primary reasons of oxygen plasma sterilization in the active discharge and the afterglow zone, respectively. The GE of UV radiation in long-distance oxygen plasma is feebleness.