COMPUTER SIMULATION OF AMPHIPHILIC AGGREGATES

这项建议要求支持调查的行为， 两亲性分子组装的计算机模拟 技术. 两亲分子是具有极性头部基团的分子 和碳氢化合物尾。 它们是肥皂的成分， 去污剂（脂肪酸），以及细胞和模型生物膜 （磷脂）。 在过去的十年里，计算机模拟已经 作为一个重要的补充，真实的实验， 研究这些复杂的系统。 建议使用现实的 分子间势模型与分子动力学 计算来研究组件的结构和动力学， 两亲分子 将特别强调 烷基链的分子内结构（侧链/反式 异构化）和分子间链-链的性质 这些系统中的位置和方向相关性。 而 长期目标是研究具有两个 烷基链，最初的工作将集中在脂肪的组装 每个头基有一条链的酸。 具体系统将 通过分子动力学研究的包括以下内容： a）负载在载体上的两亲分子（脂肪酸）的单层， 惰性基底，例如玻璃（Langmuir-Blodgett膜）。 B）负载在 一种烷基化玻璃基质（生物膜模型）。 c）在空气/水中的两亲分子的单层 界面（朗缪尔薄膜）。 特别感兴趣的是 对在聚合之前发生的所谓凝胶相的表征 单层的固化。 d）两亲分子在水溶液中的准球形聚集体 溶液（胶束）和层状聚集体，重点是 头基溶剂化和链构象的性质。 最终的目标是获得结构和动力学 关于两亲性组装体的行为的信息， 补充了目前正在进行的实验在大学 宾夕法尼亚州，和其他地方，对结构和功能， （模型）生物膜及相关系统。

This proposal asks for support to investigate the behavior of assemblies of amphiphilic molecules using computer simulation techniques. Amphiphiles are molecules with polar head groups and hydrocarbon tails. They are constituents of soaps and detergents (fatty acids), and cellular and model biomembranes (phospholipids). Over the past decade, computer simulation has emerged as an important complement to real experiments in the study of such complex systems. It is proposed to use realistic intermolecular potential models and molecular dynamics calculations to study the structure and dynamics of assemblies of amphiphiles. Particular emphasis will be placed on the intramolecular structure of the alkyl chains (gauche/trans isomerisation) and the nature of intermolecular chain-chain positional and orientational correlations in these systems. While the long-term objective is to study phospholipids which have two alkyl chains, the initial work will focus on assemblies of fatty acids with one chain per head group. The specific systems to be studied by molecular dynamics include the following: a) monolayers of amphiphilic molecules (fatty acids) supported on an inert substrate, such as glass (Langmuir-Blodgett films). b) monolayers and bilayers of amphiphilic molecules supported on an alkylated glass substrate (model biomembrane). c) monolayers of amphiphilic molecules at the air/water interface (Langmuir films). Of particular interest is the characterization of the so-called gel phase that occurs before the solidification of the monolayer. d) quasi-spherical aggregates of amphiphilic molecules in aqueous solution (micelles) and lamellar aggregates, with emphasis on the nature of the head group solvation and chain conformations. The eventual goal is to obtain structural and dynamical information on the behavior of amphiphilic assemblies that complements experiments currently underway at the University of Pennsylvania, and elsewhere, on the structure and function of (model) biomembranes and related systems.