Dielectric Barrier Discharge Atmospheric Cold Plasma for Inactivation of Pseudomonas aeruginosa Biofilms

In recent years, atmospheric cold plasma (ACP) has been widely investigated for potential application as an alternative decontamination technology in biomedical and healthcare sectors. In this study, the antimicrobial efficacy of ACP against Pseudomonas aeruginosa biofilms was investigated. The 48-h biofilms were treated inside sealed polypropylene containers with a high-voltage dielectric barrier discharge (DBD) ACP (80 kVRMS) and subsequently stored for 24 h at room temperature. Treatment for 60 s by either the direct or indirect mode of ACP exposure (inside or outside plasma discharge, respectively) reduced bacterial populations by an average of 5.4 log cycles from an initial 6.6 log10 CFU/mL. Increasing the treatment time from 60 s to 120 s and 300 s reduced biofilms to undetectable levels. According to XTT assay (a metabolic activity assay), an extended treatment time of 300 s was necessary to reduce metabolic activity of cells in biofilms by an average of 70%. Further investigation of biofilm viability by confocal laser scan- ning microscopy (CLSM) and scanning electron microscopy (SEM) demonstrated that extended ACP treatment had a detrimental effect on the viability of P. aeruginosa through disintegration of both bacterial cells and the biofilm matrix. The results of this study demonstrate the potential of a novel, in-package, high-voltage ACP decontamination approach for the inactivation of bacterial biofilms.