Direct Observation of Vesicle Dynamics, Collision, and Adhesion

CBET - 1704668PI: Schroeder， charles该奖项将支持对悬浮在流动中的囊泡动力学的实验和数值研究，囊泡是由膜包围的液体或气体组成的颗粒。本项目中的囊泡充满液体，并被脂质双层膜包围，这使得它们与生物系统中的囊泡相似。它们也类似于用于各种消费品和食品中的合成囊泡。该项目的目标是表征流动中囊泡的动力学特性，利用囊泡的行为来表征其机械特性，并研究囊泡之间的碰撞及其粘附性。为了实现这些目标，已知成分的囊泡将被放置在具有多个流体通道的微流控细胞中，以保持囊泡在周围流动中的静止。通过显微镜观察单个囊泡的变形和囊泡之间的碰撞。该项目的结果将使从业者能够设计健壮和稳定的囊泡用于产品。该项目团队将参加伊利诺伊州iRise项目，该项目与教师合作，为K-12和高中学生开发动手实验实验室。该团队还将为参加当地男孩女孩俱乐部的未被充分代表的群体的学生进行实践示范。在精确控制的稳态和振荡拉伸流中研究单个囊泡的动力学。影响囊泡形状和从稳定到不稳定形状转变的参数将被检查，包括流速，膜弯曲能，膜弹性和粘度。构造拉伸流中囊泡稳定性和变形的相图。该项目的结果将有助于解决关于囊泡形状不稳定性（如珠光）开始的实验和模拟之间的差异。本项目中使用的振荡流将使囊泡暴露于随时间变化的应变，这将暴露非定常对形状不稳定性的影响。自由悬浮囊泡的碰撞和粘附将被表征。以往的工作大多集中在弱相互作用极限，其中膜弯曲能起主导作用，膜弹性无关。然而，囊泡膜在碰撞时变形和拉伸，这被预测会引起增强的相互作用和意想不到的聚集。本项目的实验将研究这些条件下的碰撞和粘附。

CBET - 1704668PI: Schroeder, CharlesThis award will support an experimental and numerical study of the dynamics of vesicles, particles composed of liquid or gas that is surrounded by a membrane, suspended in flow. The vesicles in this project are liquid-filled and are surrounded by a lipid bilayer membrane, which makes them similar to vesicles found in biological systems. They are also similar to synthetic vesicles that are used in a variety of consumer products and foods. The goals of the project are to characterize dynamics of the vesicles in flow, to use the behavior of the vesicles to characterize their mechanical properties, and to study collisions between vesicles and their adhesion. To accomplish these goals, vesicles of known composition will be placed in a microfluidic cell that has multiple fluidic channels arranged to keep the vesicle stationary in the surrounding flow. The deformation of single vesicles and collisions among vesicles will be viewed through a microscope. The results of the project will enable practitioners to design robust and stable vesicles for use in products. The project team will participate in the Illinois iRise program, which works with teachers to develop hands-on experimental labs for K-12 and high school students. The team will also develop hands-on demonstrations for students from underrepresented groups participating in local Boys and Girls Clubs.The dynamics of single vesicles will be studied in precisely controlled steady and oscillatory extensional flow. Parameters that affect vesicle shapes and the transition from stable to unstable shapes will be examined, including flow rate, membrane bending energy, membrane elasticity and viscosity. A phase diagram for vesicle stability and deformation in extensional flow will be constructed. Results from the project will help resolve discrepancies between experiments and simulations regarding the onset of vesicle shape instabilities such as pearling. The oscillatory flow used in this project will expose vesicles to time-dependent strains, which will expose the effect of unsteadiness on shape instabilities. Collisions and adhesion of freely-suspended vesicles will be characterized. Most prior work has focused on the weak interaction limit, wherein the membrane bending energy plays a dominant role and membrane elasticity is not relevant. However, vesicle membranes deform and stretch upon collision, which has been predicted to give rise to enhanced interactions and unexpected aggregation. The experiments in this project will study collision and adhesion under these conditions.