Pore Dynamics of Lipid Vesicles under Photoinduced Oxidative Stress

Exposure of cell membrane to reactive oxygen species (ROS), can cause oxidative damage; disrupting biological functions. Oxidation of lipids alters their structural properties, compromising membrane integrity and causing cell death. Previous studies have observed degradation of lipid membranes leads to transient pores as well as total sudden catastrophic collapse of vesicles, a phenomenon recognized as vesicle explosion. However, the physical mechanism leading to explosion is unknown. Here, we discuss the mechanical response of lipid-bilayers under extreme oxidative stress. Through experiments and theoretical modeling, we demonstrate how spontaneous curvature, induced by asymmetric oxidation of the membrane, plays a key role in vesicle explosion. We propose a model of pore-opening dynamics, including oxidation, spontaneous curvature, and curling instability, which aligns with experimental observations. We characterize the dependence of explosion on the rate of ROS generation as well as lipid unsaturation. Our results could advance fundamental understandings of the stability of organelles and bio-membranes subject to oxidative insults, and provide potential insights to aide in strategizing and fine-tuning release rates for a targeted precision delivery and cell mimetic systems.