Elucidation of the Interactions of Reactive Oxygen Species and Antioxidants in Model Membranes Mimicking Cancer Cells and Normal Cells

Photosensitizers (PSs) used in photodynamic therapy (PDT) have been developed to selectively destroy tumor cells. However, PSs recurrently reside on the extracellular matrix or affect normal cells in the vicinity, causing side effects. Additionally, the membrane stability of tumor cells and normal cells in the presence of reactive oxygen species (ROS) has not been studied, and the effects of ROS at the membrane level are unclear. In this work, we elucidate the stabilities of model membranes mimicking tumor cells and normal cells in the presence of ROS. The model membranes are constructed according to the degree of saturation in lipids and the bilayers are prepared either in symmetric or asymmetric form. Interestingly, membranes mimicking normal cells are the most vulnerable to ROS, while membranes mimicking tumor cells remain relatively stable. The instability of normal cell membranes may be one cause of the side effects of PDT. Moreover, we also show that ROS levels are controlled by antioxidants, helping to maintain an appropriate amount of ROS when PDT is applied.