DIRECT MEASUREMENT OF BIO-COLLOIDAL INTERACTION FORCES

对生物过程的基本理解涉及到 吸引和排斥胶体力的知识， 确定两亲性聚集体（双层， 囊泡、微管、胶束等）以及 细胞聚集体（双层，囊泡，微管， 胶束等）以及生物大分子（DNA， 等）。 这些力是距离的复杂函数， 改变表面形态。 它们包括短程水合作用 力，货车der Walls引力，长程引力 疏水力、静电排斥力和力 与反离子和双层涨落有关。 表面 力的测量仪器允许测量这些胶体力 其分辨率为正负1埃， 分层 在过去的几年里， 我们对这些控制生物的胶体力的理解 流程. 有新的理论见解等等 复杂的实验技术 的长期目标 这项研究是为了结合新兴的理论见解， 直接测量两亲性相互作用力的能力。 这些研究还将涉及渗透压测量。 的 实验解决了广泛的问题，包括：（1） 表面力仪测量结果的比较 和渗透胁迫技术; Helfrich热力学涨落在确定 双层膜的结构和稳定性;（3）长链的性质 一系列疏水吸引相互作用， 在控制生物融合过程;（4）如何表面 磷脂-中性脂质异质性和分子间距 混合物影响双层相互作用;（5）头基的作用 稳定两性离子双层的运动;（6）是否 相互关联的运动可以产生净吸引力 带电双层之间;和（7）单分子膜的表征 以及利用扫描隧道和原子力的生物膜 显微镜 实验的重点是提供信息 可直接应用于生物两亲性组件。

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.