Abstract：
The behavior of amphiphilic molecules such as lipids, peptides and their mixtures at the air/water interface allow us to evaluate and visualize the arrangement formed in a confined and controlled surface area. We have studied the surface properties of the zwitterionic DPPC lipid and Aβ(1-40) amyloid peptide in mixed films at different temperatures (from 15 to 40 °C). In this range of temperature the surface properties of pure Aβ(1-40) peptide remained unchanged, whereas DPPC undergoes its characteristic liquid-expanded → liquid-condensed bidimensional phase transition that depends on the temperature and lateral pressure. This particular property of DPPC makes it possible to dynamically study the influence of the lipid phase state on amyloid structure formation at the interface in a continuous, isothermal and abrupt change on the environmental condition. As the mixed film is compressed the fibril-like structure of Aβ(1-40) is triggered specifically in the liquid-expanded region, independently of temperature, and it is selectively excluded from the well-visible liquid condensed domains of DPPC. The Aβ amyloid fibers were visualized by using BAM and AFM and they were Thio T positive. In mixed DPPC/Aβ(1-40) films the condensed domains (in between 11 mN/m to 20 mN/m) become irregular probably due to the fibril-like structures is imposing additional lateral stress sequestering lipid molecules in the surrounding liquid-expanded phase to self-organize into amyloids.
摘要：
两亲分子如脂质的行为，在空气/水界面的肽及其混合物使我们能够评估和可视化在有限和受控的表面积中形成的排列。我们已经研究了在不同温度（15至40°C）下混合膜中两性离子DPPC脂质和Aβ（1-40）淀粉样肽的表面特性。在此温度范围内，纯Aβ（1-40）肽的表面性质保持不变，而DPPC经历其特征性的液体膨胀→液体冷凝的二维相变，这取决于温度和侧向压力。DPPC的这种特殊性质使得动态研究脂质相态对界面淀粉样结构形成的影响成为可能。等温和环境条件的突然变化。当混合膜被压缩时，Aβ（1-40）的原纤维状结构特别在液体膨胀区域中被触发，与温度无关，并且它被选择性地从DPPC的清晰可见的液体凝聚域中排除。通过使用BAM和AFM观察Aβ淀粉样纤维，它们是ThioT阳性。在混合的DPPC/Aβ（1-40）膜中，凝聚的结构域（在11mN/m至20mN/m之间）变得不规则，可能是由于原纤维样结构在周围的液相中施加了额外的侧向应力螯合脂质分子-膨胀相自组织成淀粉样蛋白。
