Disruption of plasma membrane integrity is a primary mechanism of nanoparticle toxicity in cells. Mechanistic studies on nanoparticle-induced membrane damage have been commonly performed using model membranes with a focus on symmetric bilayers, overlooking the fact that the membrane has an asymmetric phospholipid composition. In this study, erythrocytes with normal and scrambled membrane asymmetry were utilized to examine how the loss of membrane asymmetry and the resulting alterations in the outer leaflet lipid composition affect nanoparticle-membrane interactions. Unmodified, amine-modified, and carboxyl-modified silica (30 nm) were used as nanoparticle models. Loss of membrane asymmetry was achieved by induction of eryptosis, using a calcium ionophore. Erythrocyte membrane disruption (hemolysis) by unmodified silica nanoparticles was significantly reduced in eryptotic compared to healthy cells. Amine- and carboxyl-modified particles did not cause hemolysis in either cell. In agreement, a significant reduction in the binding of unmodified silica nanoparticles to the membrane was observed upon loss of membrane asymmetry. Unmodified silica particles also caused significant cell deformation, changing healthy erythrocytes into a spheroid shape. In agreement with findings in the cells, unmodified particles disrupted vesicles mimicking the erythrocyte outer leaflet lipid composition. The degree of disruption and nanoparticle binding to the membrane was reduced in vesicles mimicking the composition of scrambled membranes. Cryo-electron microscopy revealed the presence of lipid layers on particle surfaces, pointing to lipid adsorption as the mechanism for vesicle damage. Together, findings indicate an important role for the lipid composition of the membrane outer leaflet in nanoparticle-induced membrane damage in both vesicles and erythrocytes.

中文翻译：

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膜不对称性的丧失改变了红细胞与工程二氧化硅纳米粒子的相互作用。


质膜完整性的破坏是细胞中纳米颗粒毒性的主要机制。对纳米粒子引起的膜损伤的机制研究通常使用模型膜进行，重点关注对称双层，忽略了膜具有不对称磷脂组成的事实。在这项研究中，利用具有正常和混乱膜不对称性的红细胞来检查膜不对称性的丧失以及由此产生的外叶脂质成分的改变如何影响纳米颗粒-膜相互作用。使用未改性、胺改性和羧基改性的二氧化硅（30 nm）作为纳米颗粒模型。使用钙离子载体通过诱导红细胞凋亡来实现膜不对称性的丧失。与健康细胞相比，红细胞中未修饰的二氧化硅纳米颗粒对红细胞膜的破坏（溶血）显着减少。胺基和羧基修饰的颗粒不会在任一细胞中引起溶血。一致地，在膜不对称性丧失后，观察到未改性二氧化硅纳米颗粒与膜的结合显着减少。未经修饰的二氧化硅颗粒还会导致显着的细胞变形，将健康的红细胞变成球体形状。与细胞中的发现一致，未修饰的颗粒破坏了模仿红细胞外叶脂质成分的囊泡。在模拟乱序膜组成的囊泡中，破坏程度和纳米粒子与膜的结合程度降低。冷冻电镜显示颗粒表面存在脂质层，表明脂质吸附是囊泡损伤的机制。 总之，研究结果表明，膜外叶的脂质成分在纳米颗粒诱导的囊泡和红细胞膜损伤中发挥着重要作用。