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

Abstract

Decontamination treatments of surfaces are performed on bacterial spores, albumin and brain homogenate used as models of biological contaminations in a low-pressure, inductively coupled plasma reactor operated with water-vapour-based gas mixtures. It is shown that removal of contamination can be achieved using pure H 2 O or Ar/H 2 O mixtures at low temperatures with removal rates comparable to oxygen-based mixtures. Particle fluxes (Ar + ions, O and H atomic radicals and OH molecular radicals) from water vapour discharge are measured by optical emission spectroscopy and Langmuir probe under several operating conditions. Analysis of particle fluxes and removal rates measurements illustrates the role of ion bombardment associated with O radicals, governing the removal rates of organic matter. Auxiliary role of hydroxyl radicals is discussed on the basis of experimental data. The advantages of a water vapour plasma process are discussed for practical applications in medical devices decontamination.

Chemistry in glow discharges of H2/O2mixtures: diagnostics and modelling

“…In H 2 -rich plasmas, the main mechanism for the formation of this ion is the proton transfer from H 3 + to H 2 O (reaction T 12 ), whose high rate coefficient can be justified by taking into account the difference in proton affinity of the species involved (691.0 kJ/mol for H 2 O and 422.3 kJ/mol for H 2 ). As the oxygen ratio grows, other ions become important in the mixture while H 3 + sinks, diversifying the production processes for H 3 19 ), all of which have high rate coefficients. When the hydrogen present in the mixture is lowered, the concentration of hydronium decreases and O 2 + , which is mainly produced from the direct ionization of O 2 molecules, becomes the major ion.…”

“…This ratio is highly dependent on the electron temperature, so a rise in this parameter would help reproduce the experimental results. 19 ). For HO 2 + , the reaction with H 2 to form H 3 + is nearly thermoneutral, with the forward (T 25 ) and backward (T 13 ) rate coefficients being comparable, and this equilibrium determines its concentration for H 2 -rich mixtures.…”

From patent to product? 50 years of low‐pressure plasma sterilization

“…This recipe was found to work well for bacteria, fungi, bacterial endotoxins, proteins and prions.” As a conclusion, the efficiency of a particular plasma process strongly depends on the particular strain, matrix, and surface of the object being treated. On the same setup, Fumagalli et al introduced water vapor as process gas with interesting properties regarding the removal of biological material. While the Biodecon setup is a single ICP, the setup presented in reference is a double inductively coupled plasma reactor.…”

“…As demonstrated in several publications, plasma is capable of removing biological material most effectively in the presence of reactive oxygen species with etching rates of a few nm s −1 . Unfortunately, the etching rates decrease with process time and can even stop, especially in the case of spores, but also for proteins, and lipopolysaccharides . As a consequence, reusable medical products need to be cleaned from severe contamination in a washing procedure prior to the plasma treatment, like it is also the case for other sterilization processes described in the standard ISO 17664.…”

Sterilization Effect of Wet Oxygen Plasma in the Bubbling Method

“…One hundred and eight BI-samples were used in total, and they were divided into three groups of Hayashi et al, 2006;Hayashi et al, 2008;Oh et al, 2009;Fumagalli et al, 2012 . Low-temperature gas plasmas are generated when certain gases are stimulated under a vacuum or an atmospheric pressure with radio-frequency or microwave energy.…”