DIRECT MEASUREMENT OF BIO-COLLOIDAL INTERACTION FORCES

对生物过程的基本理解包括 了解具有吸引力和排斥力的胶体力 确定两亲性聚集体(双层， 囊泡、微管、胶束等)以及 聚电解质聚集体(双层、小泡、微管、 胶束等)以及聚电解质大分子(DNA， 等)。这些力是距离和距离的复杂函数 改变表面形态。它们包括短程水合作用 力量，范德沃尔斯有吸引力，远距离有吸引力 疏水作用力、静电斥力和作用力 与反离子和双分子层波动有关。表面 作用力装置允许这些胶体力被测量 以正负1埃的分辨率从接触到 分层。 在过去的几年里，在 我们对这些控制生物的胶体力量的理解 流程。有新的理论见解和更多 复杂的实验技术。的长期目标是 这项研究是为了将新兴的理论见解和 直接测量两亲相互作用力的能力。 这些研究还将涉及渗透压力测量。这个 实验解决了广泛的问题，包括：(1) 表面力仪器测量结果的比较 和同一系统的渗透胁迫技术；(2) Helfrich热-机械涨落在确定 双分子层的结构和稳定性；(3)Long的性质 范围疏水的吸引人的相互作用可能起到作用 在控制生物融合过程中；(4)表面如何 磷脂中性脂的异质性和分子间距 混合物对双层相互作用的影响；(5)头基的作用 稳定两性离子双分子膜的运动；(6)是否 相互关联的反离子运动可以产生净吸引力 带电双层之间；以及(7)单分子层的表征 以及使用扫描隧道和原子力的生物层 显微镜。这些实验的重点是提供信息 直接适用于生物两亲性组装体。

A fundamental understanding of biological process involves a knowledge of the attractive and repulsive colloidal forces that determine interaction between amphiphitic aggregates (bilayers, vesicles, microtubules, micelles, etc.) as well as polyelectrolyte aggregates (bilayers, vesicles, microtubules, micelles, etc.) as well as polyelectrolyte macromolecules (DNA, etc.). These forces are complex functions of distance and changing surface morphology. They include short range hydration forces, van der Walls attractive forces, long range attractive hydrophobic forces, electrostatic repulsive forces and forces associated with counterion and bilayer fluctuations. The surface forces apparatus permits these colloidal forces to be measures with a resolution of plus or minus 1 angstrom from contact to layer separation. Within the past few years there has been significant advances in our understanding of these colloid forces that control biological processes. There are new theoretical insights and more sophisticated experimental techniques. The long term goal of this research is to couple the emerging theoretical insights and the ability to directly measure amphophilic interaction forces. These studies will also involve osmotic stress measurements. The experiments address a wide range of issues including: (1) a comparison of the measurements using the surface forces apparatus and the osmotic stress techniques on the same system; (2) the role of Helfrich thermal-mechanical fluctuations in determining the structure and stability of bilayers; (3) the nature of long range hydrophobic attractive interactions which may play a role in controlling biological fusion processes; (4) how surface heterogeneity and molecular spacing of phospholipid-neutral lipid mixtures affect bilayer interactions; (5) role of headgroup motion in stabilizing zwitterionic bilayers; (6) whether correlated motions of counterion can lend to net attraction between charged bilayers; and (7) characterization of monolayers and biolayers using scanning tunneling and atomic force microscopy. The experiments are focused on providing information directly applicable to biological amphiphilic assemblies.