Microbial inactivation in model tissues treated by surface discharge plasma

Microbial cells in chronic wounds seriously delay wound healing and thus the inactivation of microbial cells is a critical step in the therapeutic process. Cold atmospheric-pressure plasma (CAP) can efficiently inactivate microbial cells and could be developed into an effective strategy for topical antimicrobial treatment. However, the details of microbial inactivation in tissues by CAP, including the effective depth of the plasma and the variation of the microbial species, are still unclear. Therefore, in this study, agarose gels containing microbial cells were used as a model of infected tissues and were treated with surface discharge plasma with the working gas of argon and 1% synthetic air. It was found that the depths of microbial inactivation were proportional to the plasma treatment time and were also related to the microbial species. The ROS penetration was dependent on the plasma treatment time, the diffusion process, and the existence of microbial cells. The plasma-generated ROS caused microbial cells to release ROS, which slightly increased the ROS penetration depths. This study of microbial inactivation by plasma in model tissues could increase the mechanism of plasma inactivation and as a treatment in the biomedical field.