The exposure of biological membranes to reactive oxygen species (ROS) plays an important role in many pathological conditions such as inflammation, infection, or sepsis. ROS also modulate signaling processes and produce markers for damaged tissue. Lipid peroxidation, mainly affecting polyunsaturated phospholipids, results in a complex mixture of oxidized products, which may dramatically alter membrane properties. Here, we have employed a set of biophysical and surface-chemical techniques, including neutron and X-ray scattering, to study the structural, compositional, and stability changes due to oxidative stress on phospholipid bilayers composed of lipids with different degrees of polyunsaturation. In doing so, we obtained real-time information about bilayer degradation under in situ UV exposure using neutron reflectometry. We present a set of interrelated physicochemical effects, including gradual increases in area per molecule, head group and acyl chain hydration, as well as bilayer thinning, lateral phase separation, and defect formation leading to content loss upon membrane oxidation. Such effects were observed to depend on the presence of polyunsaturated phospholipids in the lipid membrane, suggesting that these may also play a role in the complex oxidation processes occurring in cells.

生物膜暴露于活性氧（ROS）在许多病理状况（例如炎症，感染或败血症）中起着重要作用。ROS还可以调节信号传导过程，并为受损的组织产生标志物。脂质过氧化主要影响多不饱和磷脂，导致氧化产物的复杂混合物，可能会大大改变膜的性能。在这里，我们采用了包括中子和X射线散射在内的一系列生物物理和表面化学技术，研究了由具有不同多不饱和度的脂质组成的磷脂双层上的氧化应力导致的结构，组成和稳定性变化。这样，我们获得了有关原位双层降解的实时信息。使用中子反射仪进行紫外线照射。我们提出了一系列相互关联的物理化学作用，包括每分子面积，头部基团和酰基链水合的面积逐渐增加，以及双层变薄，侧向相分离和缺陷形成，导致膜氧化时内容物损失。观察到这种效应取决于脂质膜中多不饱和磷脂的存在，表明这些也可能在细胞中发生的复杂氧化过程中起作用。