Cold microwave plasma jets for wound healing: antimicrobial efficacy, mechanisms and changes in microbial cells

Abstract

Given the increasing prevalence of antibiotic-resistant microorganisms, alternative disinfection strategies are required. This study explores the antimicrobial potential of cold atmospheric plasma (CAP) as a non-thermal decontamination method for medical applications. The results confirm the efficacy of cold microwave plasma jets in the inactivation of Staphylococcus epidermidis, Escherichia coli, Cutibacterium acnes, and Nakaseomyces glabratus. Optimal treatment conditions ensuring both the antimicrobial efficacy and the safety for living tissue were established. Experiments in enclosed or open-air environment and the use of colorimetric agents confirmed that RONS, rather than UV radiation, are primarily responsible for microbial inactivation. Possible inhibition mechanisms induced by the CAP treatment were examined using scanning (SEM) and transmission (TEM) electron microscopy. The analyses revealed progressive morphological and intracellular changes in yeast cells following the plasma treatment, including localized thinning and perforation of the cell wall, vacuole enlargement, enhanced vesicle formation, protoplast aggregation and leakage of intracellular content.