Thermodynamic and Kinetic Control of Adsorption in Complex Fluids

复杂流体吸附的热力学和动力学控制

• 批准号: 0001526
• 负责人: Igal Szleifer
• 金额: $ 28.5万
• 依托单位: Purdue Research Foundation
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2000
• 资助国家: 美国
• 起止时间: 2000-10-01 至 2004-09-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0001526&HistoricalAwards=false
• 关键词: Thermodynamic; Kinetic; Control; Adsorption; Complex

ABSTRACTCTS-0001526I. SzleiferPurdue UniversityThe adsorption of large and complex particles plays a key role in a large number of important technological processes. For example: 1) The control of protein adsorption is fundamental in the molecular design of biocompatible materials. 2) Preferential adsorption of proteins on surfaces in a given conformation is of primary importance for the design of biosensors. 3) Asphaltene aggregates adsorb on rocks or oil pipes creating serious problems for the recovery and transport of oil. 4) Processes involving adsorption of surfactants and surfactant aggregates are important in the reduction of interfacial tension and the use of surfactants as detergents. The understanding of the molecular factors that determine the adsorption behavior are then necessary for the rational design of materials with desired properties. This is also a very important fundamental problem that requires the development of theoretical approaches that are able to describe at the molecular level complex mixtures of molecules with internal degrees of freedom that are in inhomogeneous environments. The size of the particles implies large energy scales and thus in many cases the process is dominated by its kinetic behavior. Thus, the challenge is to develop reliable theoretical approaches that can describe the equilibrium and kinetic adsorption at the molecular level. Furthermore, these approaches should bridge the gap in time and length scales from atomistic to macroscopic. For example, adsorption processes in that huge time scale keeping maximal possible molecular detail.A recent developed general theoretical approach enables the study of the structural and thermodynamic properties of mixtures of chain molecules and proteins. The predictions of the theory have been shown to be in excellent quantitative agreement for the equilibrium adsorption isotherms of proteins on surfaces with grafted polymers. Here it is proposed to generalize this molecular approach to study multicomponent mixtures, charged systems and systems out of equilibrium. Namely, to extend the approach to study kinetics of adsorption. Further, the plan includes the use of conventional simulations methodologies, Monte Carlo, molecular dynamics and Brownian dynamics in a variety of systems where the computational complexity does not make the calculations prohibitively long, to check the validity of the kinetic molecular approach. In this way a hierarchy of theoretical methods that will enable the study of the equilibrium and dynamic involved in the adsorption process will be obtained. These approaches will serve the dual purpose of: 1) Bridging the gap in time and length scales between atomistic and macroscopic descriptions. This is a major theoretical challenge that will provide fundamental understanding of the behavior of these complex systems. 2) The approaches developed in this work will also be sued to build up a database for the understanding of how to control complex particle adsorption depending on the desired properties of the materials. More explicitly, the ability of tethered polymer layers, including polyelectrolytes, to reduce particle adsorption to selectively adsorb a desired kind of particle will be studied. This understanding will be used in conjunction with experimental collaborators in the rational design of biocompatible materials, drug carriers, biosensors and solubilizers. The findings from this work are also expected to have a major impact on the design of materials for other applications, such as chromatography, oil transport and detergency.Specific problems to be studied: 1) Generalization of the molecular theory to three dimensions and comparisons with full simulation studies. 2) Inclusion of electrostatic interactions and their effect on large particles and protein adsorption. (3) Systematic study of the kinetics of adsorption. (4) Effect of conformational changes on the kinetic and thermodynamic behavior of protein adsorption. (5) Thermodynamic and kinetic behavior on adsorption of proteins mixtures.

摘要-0001526I。 Szleifer 普渡大学大型复杂颗粒的吸附在大量重要工艺过程中发挥着关键作用。 例如： 1）蛋白质吸附的控制是生物相容性材料分子设计的基础。 2）蛋白质在给定构象的表面上的优先吸附对于生物传感器的设计至关重要。 3) 沥青质聚集体吸附在岩石或油管上，给石油的回收和运输带来严重问题。 4) 涉及表面活性剂和表面活性剂聚集体吸附的过程对于降低界面张力和使用表面活性剂作为洗涤剂很重要。 了解决定吸附行为的分子因素对于合理设计具有所需性能的材料是必要的。 这也是一个非常重要的基本问题，需要发展能够在分子水平上描述非均匀环境中具有内部自由度的复杂分子混合物的理论方法。 粒子的尺寸意味着大的能量尺度，因此在许多情况下，该过程由其动力学行为主导。 因此，挑战在于开发可靠的理论方法来描述分子水平上的平衡和动力学吸附。 此外，这些方法应该弥合从原子到宏观的时间和长度尺度上的差距。 例如，在如此长的时间尺度内的吸附过程保持最大可能的分子细节。最近开发的通用理论方法使得能够研究链分子和蛋白质混合物的结构和热力学性质。 该理论的预测已被证明与接枝聚合物表面上蛋白质的平衡吸附等温线具有极好的定量一致性。 这里建议推广这种分子方法来研究多组分混合物、带电系统和不平衡系统。 即，扩展研究吸附动力学的方法。 此外，该计划还包括在各种系统中使用传统的模拟方法、蒙特卡罗、分子动力学和布朗动力学，以检查动力学分子方法的有效性，在这些系统中，计算复杂性不会使计算变得过长。 通过这种方式，将获得能够研究吸附过程中涉及的平衡和动态的理论方法的层次结构。 这些方法将达到双重目的：1）弥合原子描述和宏观描述之间时间和长度尺度的差距。 这是一个重大的理论挑战，它将提供对这些复杂系统行为的基本理解。 2）这项工作中开发的方法也将用于建立一个数据库，以了解如何根据材料所需的性能控制复杂颗粒的吸附。 更明确地，将研究包括聚电解质在内的束缚聚合物层减少颗粒吸附以选择性吸附所需种类颗粒的能力。 这种理解将与实验合作者一起用于生物相容性材料、药物载体、生物传感器和增溶剂的合理设计。 这项工作的结果预计也会对其他应用的材料设计产生重大影响，例如色谱、油传输和去污剂。要研究的具体问题：1）将分子理论推广到三个维度并与完整的模拟研究。 2) 包括静电相互作用及其对大颗粒和蛋白质吸附的影响。 (3)吸附动力学的系统研究。 (4)构象变化对蛋白质吸附动力学和热力学行为的影响。 (5)蛋白质混合物吸附的热力学和动力学行为。