Tension Effects on Phase Transitions in Biomimetic Bilayer Membranes

该奖项的研究目标是确定仿生膜在张力下的相图。 真核细胞的膜是数百种脂质物质的混合物。 脂质的多样性使膜能够相分离并形成称为筏的结构域，其在细胞功能如信号传导和运输中起关键作用。作为温度和组成的函数，已经广泛地研究了筏形成的相变。然而，相图的第三维，即，由于膜张力难以控制和量化，因此张力仍然未被探索。为了克服这一挑战，PI将开发两种新的方法，毛细管微观力学和电变形，其中张力是由伴随着囊泡（封闭膜）变形的区域扩张来调节的。将这些实验工具应用于张力的研究？如果成功的话，新的张力控制技术将允许确定三元仿生脂质双层的完整相图。从这项工作中获得的知识可能会导致对生物力学信号转导机制的潜在变革性见解，该机制将膜张力的变化与细胞形状和运动性的变化结合起来。这将有利于开发利用细胞信号传导和运输机制的生物工程应用，例如，靶向药物输送。该奖项的教育部分将涉及将膜生物物理学主题引入传统工程课程。特别是，PI将把这项研究的结果纳入研究生课程复杂流体和界面。PI还将利用布朗大学成功的外展计划，向公众宣传这项工作的相关性和重要性，并吸引科学和工程领域代表性不足的群体的学生。

The research objective of this award is to determine the phase diagram of biomimetic membranes under tension. Membranes in eukaryotic cells are mixtures of hundreds of lipid species. The lipid diversity enables membranes to phase separate and form domains, called rafts, which play a critical role in cell functions such as signaling and trafficking. The phase transitions underlying raft formation have been extensively studied as a function of temperature and composition. However, the third dimension of the phase diagram, i.e., the tension, is still unexplored because membrane tension is difficult to control and quantify. To overcome this challenge, the PI will develop two novel approaches, capillary micromechanics and electrodeformation, in which the tension is regulated by the area dilation accompanying deformation of a vesicle (a closed membrane). These experimental tools will be applied to study the tension?induced domain formation and evolution.If successful, the new tension-control techniques would allow to determine the complete phase-diagram of ternary biomimetic lipid bilayers. The knowledge gained from this work could lead to potentially transformative insights into the biomechanical signal transduction mechanisms that couple changes in membrane tension to changes in cell shape and motility. This will benefit the development of bioengineering applications that exploit the cell signaling and trafficking machinery, e.g., targeted drug delivery. The educational component of this award will involve the introduction of membrane biophysics topics into the traditional engineering curriculum. In particular, the PI will incorporate the results from this research in the graduate course Complex Fluids and Interfaces. The PI will also leverage successful outreach programs at Brown University to communicate the relevance and significance of the work to the general public and attract students from underrepresented groups in science and engineering.