Adhesion Deformation and Fusion of Bilayer Vesicles and Other Amphiphilic Structures in Solution

两亲结构（如双层结构、囊泡、微乳液滴和生物膜）之间的作用力伴随着结构在接近和接触时的弹性变形。这些变形依赖于聚集体间和聚集体内的力及其耦合。本项目是使用直接力测量、冷冻断裂和原位冷冻水合物电子显微镜技术研究黏附、融合和伴随的结构变形。改进了实验条件，测试了波动、静电相互作用、水化和疏水相互作用对黏附和融合过程的影响。这是第一次系统地了解聚集体之间和聚集体内部相互作用之间的耦合以及当两亲性结构接触时产生的结构修饰。视频记录系统允许人们使用表面力设备实时跟踪融合过程。虽然在不同的实验室中有许多这样的设备，但没有一个像这项工作那样被用于研究聚变动力学。将快速冷冻、无伪影冻裂和原位冷冻水合电镜结合应用于两亲性结构也是前所未有的。该技术提供了具有分子分辨率的三维结构转变的直接图像。该项目将对涉及双层和膜间相互作用的所有现象的理论和实践产生重大影响。对于胶束、双分子层、囊泡、微乳液滴、泡沫、乳剂和表面活性剂包覆的胶体颗粒的融合过程中的基本力和分子事件的新见解将是特别重要的，因为这一直是胶体和生物科学关注的焦点。囊泡的稳定性及其作为药物载体的用途，胶体分散体的稳定性，泡沫和乳剂的破裂和形成，表面活性剂在浮选中的有效性，以及边界润滑剂的磨损，这些都是对基本机制缺乏理解的例子。最重要的可能是直接研究真正的生物膜的相互作用和其他涉及生物大分子的特定相互作用的能力。

Forces between amphiphilic structures such as bilayers, vesicles, microemulsion droplets and biological membranes are accompanied by elastic deformation of the structures as they approach and come into contact. These deformations are dependent on both the inter-aggregate and intra-aggregate forces and their coupling. This project is a study of the adhesion, fusion and accompanying structure deformations using direct force measurements, freeze-fracture, and in-situ frozen hydrate electron microscopy techniques. The experimental conditions are modified to test the effects of undulation, electrostatic interactions, hydration and hydrophobic interactions on the adhesion and fusion process. This is the first systematic effort to understand the coupling between inter-and intra-aggregate interactions and the resulting structural modifications that occur when amphiphilic structures are brought into contact. A video recording system allows one to follow the fusion process in real time using a surface forces apparatus. Though a number of these apparatus exist in various laboratories, none is being deployed to study the dynamics of fusion as in this work. The combination of rapid freezing, artifact-free freeze-fracture and in-situ frozen-hydrated electron microscopy applied to amphiphilic structures is also unprecedented. The techniques present direct images of three-dimensional structural transitions with molecular resolution. This project should have a major impact on both the theory and practice of all phenomena involving interbilayer and intermembrane interactions. The expected new insights into the fundamental forces and molecular events accompanying the fusion of micelles, bilayers, vesicles, microemulsion droplets, foams, emulsions and surfactant- coated colloidal particles will be especially important as this has been the focus of much attention in the colloid and biological sciences. The stability of vesicles and their usefulness as drug carriers, the stability of colloidal dispersions, breaking and creating foams and emulsions, the effectiveness of surfactants in flotation, and the wear of boundary lubricants are all examples where understanding of basic mechanisms are still lacking. Of greatest possible importance is the ability to directly study the interactions of real biological membranes and other specific interactions involving biological macromolecules.