In vitro antimicrobial effects and mechanism of atmospheric-pressure He/O2 plasma jet on Staphylococcus aureus biofilm

Research output: Journal Publications and Reviews (RGC: 21, 22, 62)21_Publication in refereed journalpeer-review

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  • Zimu Xu
  • Jie Shen
  • Cheng Cheng
  • Shuheng Hu
  • Yan Lan


Original languageEnglish
Article number105201
Journal / PublicationJournal of Physics D: Applied Physics
Issue number10
Publication statusPublished - 9 Feb 2017


The antimicrobial effects and associated mechanism of inactivation of Staphylococcus aureus (S. aureus) NCTC-8325 biofilms induced by a He/O2 atmospheric-pressure plasma jet (APPJ) are investigated in vitro. According to CFU (colony forming units) counting and the resazurin-based assay, the 10 min He/O2 (0.5%) APPJ treatment produces the optimal inactivation efficacy (>5 log10 ml-1) against the S. aureus biofilm and 5% of the bacteria enter a viable but non-culturable (VBNC) state. Meanwhile, 94% of the bacteria suffer from membrane damage according to SYTO 9/PI counterstaining. Scanning electron microscopy (SEM) reveals that plasma exposure erodes the extracellular polymeric substances (EPS) and then the cellular structure. The H2DCFDA-stained biofilms show larger concentrations of intracellular reactive oxygen species (ROS) in membrane-intact bacteria with increasing plasma dose. The admixture of oxygen in the working gas highly contributes to the deactivation efficacy of the APPJ against S. aureus and the plasma-induced endogenous ROS may work together with the discharge-generated ROS to continuously damage the bacterial membrane structure leading to deactivation of the biofilm microbes.

Research Area(s)

  • atmospheric-pressure plasma jet (APPJ), biofilm inactivation, reactive oxygen species (ROS), Staphylococcus aureus

Citation Format(s)