Chemical analysis of reactive species and antimicrobial activity of water treated by nanosecond pulsed DBD air plasma

Publication date: Available online 31 October 2015 Source:Clinical Plasma Medicine Author(s): R. Laurita, D. Barbieri, M. Gherardi, V. Colombo, P. Lukes Deionized water, phosphate buffer and dilute electrolyte solution from sodium dihydrogenphosphate were treated by nanosecond pulsed DBD air plasma. Hydrogen peroxide, nitrates and nitrites produced by plasma treatment were measured by means of both quantitative and semi-quantitative methods. Phenol was used as chemical probe for ROS and RNS. Post-discharge kinetic of phenol degradation gave evidence of the formation of peroxynitrite by H+-catalyzed reaction of H2O2 and NO 2 - in plasma activated water (PAW). Antimicrobial activity of two types of PAWs prepared by exposing deionized water with DBD air plasma for different times (5 and 10min, named PAW-5MIN and PAW-10MIN, respectively) was investigated on Candida albicans and Staphylococcus aureus, among the most common causes of nosocomial infections. The activity of PAWs decreased strongly with post-discharge time. For PAW-5MIN the activity held for about 30min while for PAW-10MIN just less than 15min. This correlated with the time evolution of peroxynitrite chemistry observed on phenol in both PAWs. OH, NO2 radicals with acidified  NO 2 - and acidic pH itself were most likely the main biocidal agents in PAWs acting on tested microorganisms. Since the initial concentrations of H2O2 and  NO 2 - (as precursors of peroxynitrite formation in PAW) were co...
Source: Clinical Plasma Medicine - Category: Research Source Type: research