Sterilization and decontamination of medical instruments by low pressure plasma discharges: Application of ternary mixtures

Summary form only given. Application of non-equilibrium plasma discharges for sterilization of medical instruments appeared to be promising alternative to commonly used sterilization techniques. This is due to advantageous and unique properties of plasma discharges allowing highly effective treatment without necessity to use toxic substances and maintaining low temperature conditions favorable for treatment of heat degradable articles. Moreover, it was already demonstrated among others by our group that the low-pressure plasma discharges are capable not only to kill bacteria and bacterial spores, but also to remove or inactivate various pathogenic biomolecules such as bacterial endotoxins1´2 or proteins2. However, optimal conditions leading to surface sterilization and decontamination differ significantly, owing to the different pathways leading to the desired effect. According to the results obtained using low pressure plasma discharges, the efficiency of sterilization of bacterial spores is typically linked with the intensity of UV radiation emitted by the plasma discharge. The intense UV emission in the spectral range optimal for the spores killing is commonly achieved using oxygen-nitrogen discharge mixture. Nevertheless, this mixture was found to be inefficient for the fast elimination or removal of biomolecules. The different discharge mixtures needed for sterilization and physical removal of biological substances has important consequences for the optimization of the treatment in the case of a real situation when the requirement is to guarantee both sterility and complete elimination of pathogens. This implies either application of two step plasma treatment -the first step favoring killing of spores and the second physical removal of pathogens-, or, as it will be demonstrated in this contribution by utilization of ternary discharge mixtures that allow to optimize both UV intensity and removal rate of biomolecules.