Molecular dynamics simulations of membrane properties affected by plasma ROS based on the GROMOS force field

Cold atmospheric plasma (CAP) has attracted substantial attention in the field of medical disinfection because its main components, reactive oxygen species (ROS), have a strong destructive effect on various cell components. The cell membrane plays an important role in maintaining proper cellular function by blocking harmful substances such as ROS. In this paper, we used molecular dynamics simulations to study the behaviour of different ROS at the membrane-water interface. The results showed that the cell membrane presented a weak barrier to hydrophobic ROS (O-2) but effectively prevented hydrophilic ROS (OH, HO2, H2O2) from entering the cell. The plasma treatment significantly enhanced the permeability of the cell membrane to HO2, while the energetic barrier to other types of ROS changed only slightly. O-2 very likely stopped in the centre of the lipid bilayer when crossing the membrane and there attacked the unsaturated region of the phospholipid. Cholesterol was most likely oxidized by HO2, causing a condensing effect that destroyed the integrity and fluidity of the cell membrane. The study also found that large amounts of ROS decreased the thickness of the cell membrane, and the phospholipid arrangement became disordered.