Université Lyon, Université Claude Bernard Lyon 1, CNRS, Institut Lumière Matière, F-69622 Villeurbanne, France.
Doctoral School for Science and Technology, Platform for Research in NanoSciences and Nanotechnology, Campus Pierre Gemayel, Lebanese University , Fanar-Metn BP 90239 Beirut, Lebanon.
Langmuir. 2017 Mar 7;33(9):2444-2453. doi: 10.1021/acs.langmuir.6b03276. Epub 2017 Feb 24.
In vivo lipid membranes interact with rough supramolecular structures such as protein clusters and fibrils. How these features whose size ranges from a few nanometers to a few tens of nanometers impact lipid and protein mobility is still being investigated. Here, we study supported phospholipid bilayers, a unique biomimetic model, deposited on etched surfaces bearing nanometric corrugations. The surface roughness and mean curvature are carefully characterized by AFM imaging using ultrasharp tips. Neutron specular reflectivity supplements this surface characterization and indicates that the bilayers follow the large-scale corrugations of the substrate. We measure the lateral mobility of lipids in both the fluid and gel phases by fluorescence recovery after patterned photobleaching. Although the mobility is independent of the roughness in the gel phase, it exhibits a 5-fold decrease in the fluid phase when the roughness increases from 0.2 to 10 nm. These results are interpreted with a two-phase model allowing for a strong decrease in the lipid mobility in highly curved or defect-induced gel-like nanoscale regions. This suggests a strong link between membrane curvature and fluidity, which is a key property for various cell functions such as signaling and adhesion.
在体内，脂质膜与粗糙的超分子结构相互作用，如蛋白质簇和纤维。这些大小从几纳米到几十纳米不等的特征如何影响脂质和蛋白质的流动性仍在研究中。在这里，我们研究了沉积在具有纳米级波纹的蚀刻表面上的支撑磷脂双层，这是一种独特的仿生模型。使用超尖锐尖端的 AFM 成像对表面粗糙度和平均曲率进行了仔细的表征。中子镜面反射率补充了这种表面特性，并表明双层膜跟随基底的大尺度波纹。我们通过图案化光漂白后的荧光恢复来测量流体相和凝胶相中的脂质横向流动性。尽管在凝胶相中，流动性与粗糙度无关，但当粗糙度从 0.2nm 增加到 10nm 时，流动性在流体相中下降了 5 倍。这些结果用允许脂质在高度弯曲或缺陷诱导的类似凝胶的纳米级区域中流动性大大降低的两相模型进行了解释。这表明膜曲率和流动性之间存在很强的联系，这是各种细胞功能（如信号转导和黏附）的关键特性。
