Optical emission spectroscopy characterization of oxygen plasma during degradation of Escherichia coli

Abstract

Optical emission spectroscopy was applied for plasma characterization during sterilization of substrates contaminated with bacteria. The amount of 1010∕ml cells of Escherichia coli was carefully applied to glass substrates and exposed to oxygen plasma glow discharge at different pressures between 30 and 200Pa. Plasma was created in a glass discharge tube by an inductively coupled rf generator at the frequency of 27.12MHz and output power of about 250W. The electron temperature and plasma density were estimated with a double Langmuir probe. They were between 3 and 5eV and 2 and 35×1015m−3. Density of neutral oxygen atoms was measured with a catalytic probe, and was between 2 and 6×1021m−3. Optical emission spectroscopy was performed with a low resolution spectrometer. The emission from carbon monoxide and nitrogen molecules was used to monitor the evolution of bacteria degradation. Both signals expressed a well defined maximum corresponding to peak erosion of bacteria by plasma radicals. As the sterilization was accomplished, both CO and N2 lines fell below the detection limit of the spectrometer. The bacteria degradation was also monitored by scanning electron microscope (SEM) and culturing. The SEM images corresponded well with the evolution of CO and N2 lines so the optical emission spectroscopy found a reliable tool for monitoring the sterilization process.

Low-pressure water vapour plasma treatment of surfaces for biomolecules decontamination

“…Depending on the reactor design, Ar/O 2 gas mixtures showed best biomaterial removal efficiency in RF discharges [9][10][11][12], when treated samples were placed in to active plasma. In addition, interesting results in terms of sterilization capability of plasmas were also reached using H 2 /O 2 gas mixtures [13,14], N 2 /O 2 gas mixtures [15][16][17] or pure O 2 discharge plasma [18,19].…”

Elimination of Biological Contaminations from Surfaces by Plasma Discharges: Chemical Sputtering

“…Those studies are, however, not easy to compare, because they were made with a variety of different germs, such as Escherichia coli, Geobacillus stearothermophilus, Bacillus atrophaeus, Deinococcus radiodurans, and different plasma systems. Furthermore, the utilized reactors differ in their geometry, in the type of plasma excitation such as DC, [31] RF, [20,[32][33][34][35] or MW [36][37][38] as well as in the employed operational parameters. In some experiments the objects to be treated are placed in the active discharge, others use the plasma afterglow.…”

Theoretical insight into Ar–O2surface-wave microwave discharges

“…O 2 and Ar-O 2 plasmas have been successfully used for oxide films deposition [9,10], synthesis of metal oxide nanowires [11], sterilization and decontamination of medical instruments [1,12,13,14,15] and polymer surface treatment [3,16,17,18]. Furthermore, the O( 1 D) atoms present in Ar-O 2 plasma were shown to have the potential for surface activation [2].…”