Abstract：
Bottom-up design of biomimetic organelles has gained recent attention as a route towards understanding the transition between non-living matter and life. Despite various artificial lipid membranes being developed, the specific relations between lipid structure, composition, interfacial properties, and morphology are not currently understood. Sponge-phase droplets contain dense, nonlamellar lipid bilayer networks that capture the complexities of the endoplasmic reticulum (ER), making them ideal artificial models of such organelles. Here, we combine ultrafast two-dimensional infrared (2D IR) spectroscopy and molecular dynamics simulations to investigate the interfacial H-bond networks in sponge-phase droplets composed of glycolipid and nonionic detergents. In the sponge phase, the interfacial environments are more hydrated and water molecules confined to the nanometer-scale aqueous channels in the sponge phase exhibit dynamics that are significantly slower compared to bulk water. Surfactant configurations and microscopic phase separation play a dominant role in determining membrane curvature and slow dynamics observed in the sponge phase. The studies suggest that H-bond networks within the nanometer-scale channels are disrupted not only by confinement but also by the interactions of surfactants, which extend 1-2 nm from the bilayer surface. The results provide a molecular-level description for controlling phase and morphology in the design of synthetic lipid organelles.
摘要：
仿生细胞器的自下而上设计作为理解非生命物质与生命之间过渡的途径，最近引起了人们的关注。尽管开发了各种人工脂质膜，脂质结构之间的特定关系，composition,界面性质，和形态学目前还不清楚。海绵相液滴含有致密的，非层状脂质双层网络，捕获内质网（ER）的复杂性，使它们成为这种细胞器的理想人工模型。这里,我们结合超快二维红外（2DIR）光谱和分子动力学模拟来研究由糖脂和非离子洗涤剂组成的海绵相液滴中的界面H键网络。在海绵阶段,界面环境更加水合，水分子被限制在海绵相的纳米级水性通道中，表现出与散装水相比明显更慢的动力学。表面活性剂构型和微观相分离在确定海绵相中观察到的膜曲率和缓慢动力学中起着主导作用。研究表明，纳米级通道内的H键网络不仅受到限制，而且还受到表面活性剂的相互作用的破坏。从双层表面延伸1-2nm。该结果为控制合成脂质细胞器设计中的相和形态提供了分子水平的描述。
