Direct Observation of Vesicle Dynamics, Collision, and Adhesion

CBET-1704668PI：Schroeder，Charles该奖项将支持对流动中悬浮的囊泡动力学的实验和数值研究，囊泡是由液体或气体组成的颗粒，由膜包围。这个项目中的囊泡是充满液体的，并被脂质双层膜包围，这使得它们类似于生物系统中的囊泡。它们也类似于在各种消费品和食品中使用的合成泡囊。该项目的目标是表征小泡在流动中的动力学，使用小泡的行为来表征它们的机械性能，并研究小泡之间的碰撞和它们的粘连。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体单元中，以保持囊泡在周围流动中保持不变。单个小泡的变形和小泡之间的碰撞将通过显微镜观察。该项目的结果将使从业者能够设计出用于产品的坚固和稳定的囊泡。该项目团队将参与伊利诺伊州iRise项目，该项目与教师合作，为K-12和高中生开发动手实验实验室。该团队还将为参加当地男孩和女孩俱乐部的未被充分代表的群体的学生开发动手演示。将在精确控制的稳定和振荡的伸展流动中研究单个囊泡的动力学。将考察影响囊泡形状和从稳定到不稳定形状转变的参数，包括流速、膜弯曲能、膜弹性和粘度。建立了囊泡在拉伸流动中稳定性和变形的相图。该项目的结果将有助于解决实验和模拟之间的差异，关于囊泡形状不稳定的开始，如珍珠化。这个项目中使用的振荡流动将使囊泡暴露在依赖于时间的应变中，这将暴露不稳定对形状不稳定性的影响。自由悬浮小泡的碰撞和粘连将被描述。以往的工作大多集中在弱相互作用极限上，其中膜弯曲能起主导作用，膜弹性不起作用。然而，囊泡膜在碰撞时会变形和拉伸，这已被预测会导致增强的相互作用和意外的聚集。本项目中的实验将研究在这些条件下的碰撞和粘合。

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.