Polyelectrolyte-Colloid Interactions

9619722 Dubin聚电解质与胶体颗粒和表面的相互作用是许多工业过程和生物现象的核心，如分散稳定和絮凝，以及结合。蛋白质到DNA。由于这些相互作用主要是库仑的，因此PI将研究关键静电量——胶体表面电荷密度、聚合物线性电荷密度和离子强度——可以系统变化的系统。聚电解质将是阳离子的，如聚（二甲基二烯丙基氯化铵）和阴离子的，如聚（丙烯酰胺-2-甲基丙磺酸）及其共聚物。研究的胶体粒子将是胶束、囊泡、蛋白质和树突。其中一些系统具有单独的意义，例如用于分离蛋白质的聚电解质-蛋白质复合物，用于去除微量有机物的聚电解质-胶束复合物，以及用于药物递送的聚电解质囊泡复合物。其中一个目标是评估两种截然不同的理论处理方法。第一个模型预测了聚电解质在带相反电荷的表面（大颗粒）上吸附的二级相变。第二章描述了带电配体（小粒子）在反离子缩合理论背景下与多离子的结合。此外，还将讨论与具体实验系统有关的若干问题：(a)与多晶体结合后，多晶体是否会重新结构？(b)非离子型共表面活性剂的“间隔剂效应”能否定量解释？(c)复合物和凝聚体中的蛋白质在三级结构、旋转自由和酶活性方面的状态如何？(d)蛋白质-聚电解质和胶束-聚电解质凝聚体的微观结构是什么？(e)聚电解质吸附如何影响脂质体的渗透性？%%%%这个项目是在胶体颗粒、表面和聚电解质领域，它们的相互作用对许多生物和工业过程具有重要意义

9619722 Dubin The interaction of polyelectrolytes with colloidal particles and surfaces is central to a many industrial processes and biological phenomena, such as dispersion stabilization and flocculation, and the binding of. proteins to DNA. Since these interactions are predominantly coulombic,the PI will study systems in which key electrostatic quantities -- colloid surface charge density, polymer linear charge density, and ionic strength,--can be systematically varied. The polyelectrolytes will be both cationic, such as poly(dimethyldiallylammonium chloride), and anionic, such as poly(acrylamido-2-methylpropanesulfonate) and copolymers thereof. The colloidal particles studied will be micelles, vesicles, proteins and dendrimers. Some of these systems have individual significance, e.g. polyelectrolyte-protein complexes for protein separations, polyelectrolyte-micelle complexes for removal of trace organics, and polyelectrolyte vesicle complexes for drug delivery. One of the goals will be to evaluate two very distinct theoretical treatments. The first predicts second-order phase transitions for polyelectrolyte adsorption on oppositely charged surfaces (large particles. The second describes the binding of charged ligands (small particles) to polyions within the context of counterion condensation theory. In addition, a number of questlons related to specific experimental systems will be addressed: (a) Do mlcelies restructure upon binding to polyions? (b) Can the "spacer effect" of nonionic co- surfactants be quantitatively explained? (c) What is the state of proteins in complexes and coacervates, in terms of tertiary structure, rotational freedom, and enzyme activity? (d) What is the microstructure of protein-polyelectrolyte and micelle-polyelectrolyte coacervates? and (e) How does polyelectrolyte adsorption affect liposome permeability? %%%% This project is in the area of colloidal particles, surfaces, and polyelectrolytes, whose interactions have importan t implications to a number of biological and industrial processes ***