Interfacial rheology and direct imaging reveal domain-templated network formation in phospholipid monolayers penetrated by fibrinogen
Interfacial rheology and direct imaging reveal domain-templated network formation in phospholipid monolayers penetrated by fibrinogen
复制标题
界面流变学和直接成像揭示了纤维蛋白原渗透的磷脂单层中的域模板网络形成
DOI：
10.1039/c9sm01519a
复制
发表时间：
2019
期刊：
影响因子：
3.4
通讯作者：
Squires, Todd M.
中科院分区：
文献类型：
--
作者：
Williams, Ian;Zasadzinski, Joseph A.;Squires, Todd M.
磷脂遍布自然界，包括可降低肺表面张力并促进呼吸的肺表面活性剂 (LS) 层。纤维蛋白原是一种参与血液凝固过程的蛋白质，与 LS 失活和急性呼吸窘迫综合征等疾病的进展有关。然而，人们对纤维蛋白原和 LS 在空气-水界面上的相互作用知之甚少。通过结合微流变学、共焦和落射荧光显微镜方法，我们量化了界面剪切响应，并直接对模型 LS 单层被纤维蛋白原渗透时的形态演变进行成像。当注入单层磷脂二棕榈酰磷脂酰胆碱（DPPC，LS 的主要成分）下方的底相时，纤维蛋白原优先渗透无序的液体扩展 (LE) 区域，并积聚在 LE DPPC 和液体浓缩 (LC) DPPC 域之间的边界上。因此，纤维蛋白原具有线活性。聚集体从LC域边界生长，最终形成渗透网络。与纯 DPPC 相比，该网络使界面变硬，并赋予渗透的单层以类似于弱凝胶的粘弹性特性。当 DPPC 单层最初被压缩到超出 LE-LC 共存范围时，硬化明显更加温和，并且渗透的单层保留了粘性主导的、类似 DPPC 的特性。
Phospholipids are found throughout the natural world, including the lung surfactant (LS) layer that reduces pulmonary surface tension and enables breathing. Fibrinogen, a protein involved in the blood clotting process, is implicated in LS inactivation and the progression of disorders such as acute respiratory distress syndrome. However, the interaction between fibrinogen and LS at the air–water interface is poorly understood. Through a combined microrheological, confocal and epifluorescence microscopy approach we quantify the interfacial shear response and directly image the morphological evolution when a model LS monolayer is penetrated by fibrinogen. When injected into the subphase beneath a monolayer of the phospholipid dipalmitoylphosphatidylcholine (DPPC, the majority component of LS), fibrinogen preferentially penetrates disordered liquid expanded (LE) regions and accumulates on the boundaries between LE DPPC and liquid condensed (LC) DPPC domains. Thus, fibrinogen is line active. Aggregates grow from the LC domain boundaries, ultimately forming a percolating network. This network stiffens the interface compared to pure DPPC and imparts the penetrated monolayer with a viscoelastic character reminiscent of a weak gel. When the DPPC monolayer is initially compressed beyond LE–LC coexistence, stiffening is significantly more modest and the penetrated monolayer retains a viscous-dominated, DPPC-like character.