Abstract
Objective A direct-current, cold atmospheric-pressure air plasma microjet (PMJ) was performed to inactivate Staphylococcus aureus (S. aureus) and Enterococcus faecalis (E. faecalis) in air. The process of sterilization and morphology of bacteria was observed. We wish to know the possible inactivation mechanisms of PMJ and explore a potential application in dental and other temperature sensitive treatment. Methods In this study, we employed a direct current, atmospheric pressure, cold air PMJ to inactivate bacterias. Scanning electron microscopy was employed to evaluate the morphology of S. aureus and showed rupture of cell walls after the plasma treatment and Optical emission spectrum (OES) were used to understand the possible inactivation mechanisms of PMJ. Results The inactivation rates could reach 100% in 5 min. When the distance between the exit nozzle of the PMJ device and Petri dish was extended from 1 cm to 3 cm, effective inactivation was also observed with a similar inactivation curve. Conclusion The inactivation of bacteria is attributed to the abundant reactive oxygen and nitrogen species, as well as ultroviolet radiation in the plasma. Different life spans and defensibilities of these killing agents may hold the key to understanding the different inactivation curves at different treatment distances.
Highlights
Atmospheric-pressure cold plasma has attracted considerable attention recently in the field of biomedical engineering, due to its extensive clinical applications, such as bacteria sterilization[1,2,3], cancer therapy[4,5], blood coagulation[6,7], wound healing[8,9] and tooth whitening[10]
Y.Tian et al / Journal of Biomedical Research, 2010, 24(4): 264-269 were observed when the distance between the plasma microjet (PMJ) and Petri dish was extended from 1 cm to 3 cm
The inactivation rate of the bacteria was defined as the percentage decrease in CFU counts following treatment
Summary
Atmospheric-pressure cold plasma has attracted considerable attention recently in the field of biomedical engineering, due to its extensive clinical applications, such as bacteria sterilization[1,2,3], cancer therapy[4,5], blood coagulation[6,7], wound healing[8,9] and tooth whitening[10]. We employed a direct current, atmospheric pressure, cold air plasma microjet (PMJ) to inactivate Staphylococlus (S. aureus) and Enterococcus faecalis (E. faecalis) in air. Y.Tian et al / Journal of Biomedical Research, 2010, 24(4): 264-269 were observed when the distance between the PMJ and Petri dish was extended from 1 cm to 3 cm. Scanning electron microscope (SEM) and Optical emission spectrum (OES) were used to understand the possible inactivation mechanisms of PMJ
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