Atmospheric non-equilibrium plasma sterilization technology has been applied in the food processing, medical and health fields because of advantages such as short application time, low-temperature operation, high efficiency and safety. Research has shown that the active particles in the plasma play a decisive role in sterilization. However, the micromechanisms underlying the interaction between the active particles and biological components remain unclear. In this paper, with the common deteriorative microorganism Saccharomycodes as the research object, we examined the interaction between reactive oxygen species (O, OH, HO2 and H2O2) and glucan in the cell wall using a reactive force field molecular dynamics (ReaxFF MD) simulation methodology. We found that these reactive oxygen species reacted with the glucan structure by hydrogen abstraction reactions to cleave chemical bonds (C–O and C–C), resulting in cell wall destruction. Of these species, the O and OH species attract H atoms from the structure; these atoms are highly active and can easily break C–C bonds and release monosaccharides from the branched glucan chains. The H atoms in HO2 and H2O2 are strongly attracted to the glucan structure. Next, the C–O bonds are easily broken, leading to destruction of the chain structure, mainly because of the cleavage of the glucoside bonds. This simulation study adds to the understanding of the micromechanism of the ROS-mediated destruction of the cell wall glucan of Saccharomyces cerevisiae and of plasma sterilization at the atomic level.

Cold atmospheric plasma shows a satisfactory ability to inactivate bacterial biofilms that are difficult to remove using conventional methods in some cases. However, the researches on the inactivation mechanism are not quite sufficient. Poly-β-1-6-N-acetylglucosamine (PNAG), which is one of the important components in some biofilms, was used as the research subject, and the related mechanism of action triggered by different concentrations of the OH in plasma was studied using reactive molecular dynamics simulations. The results showed that OH radicals could not only trigger the hydrogen abstraction reaction leading to cleavage of the PNAG molecular structure, but undergo an OH addition reaction with PNAG molecules. New reaction pathways appeared in the simulations as the OH concentration increased, but the reaction efficiency first increased and then decreased. The simulation study in this paper could, to some extent, help elucidate the microscopic mechanism of the interaction between OH radicals in plasma and bacterial biofilms at the atomic level.