Collaborative Research: Structure and Dynamics of Liquid Interfaces Studied by X-Ray and Neutron Scattering

非技术摘要细胞的许多生物学活动都发生在膜上。因此，在半导体表面构建人工膜是生物传感器研究的一个热点。本工作的目标是使用一种称为相干X射线散射的复杂技术来研究这种支撑膜的结构和动力学性质。测量结果将被用于建立膜运动的流体动力学模型，并确定重要的物理参数，如表面张力、粘度和弹性模量值。这项研究将从支撑在底物上的脂质双层开始，并通过添加纤维素膜等中间缓冲层，或通过将底物上方的膜与蛋白质捆绑在一起，来探索膜从底物中释放时其动力学的变化。这一研究结果将对聚合物薄膜在复合材料、粘合剂、包装、生物相容性材料和生物传感器中的应用产生重大影响。学生，包括来自代表性不足的群体，将在国家实验室接受使用国家或最先进的同步辐射X射线设备的培训。技术摘要本项目将利用掠入射X射线散射和利用相干X射线束的X射线光子相关光谱(XPCS)来研究液体界面的结构和动力学，包括聚合物流体界面和脂类双层。结合粘弹性流体力学的理论处理，这项工作将提供分析薄膜液体的界面张力、粘度和弹性模数的方法。研究了聚合物薄膜在玻璃化转变温度附近的反常动力学行为。聚合物方面的工作将为研究脂质双层膜系统的动态波动提供起点。在裸露或有衬垫的衬底上，水中的支撑膜提供了具有足够表面积的取向薄膜，可以用X射线或中子散射、XPCS或中子自旋回波等技术进行研究。我们将对这些层状体系的结构、构象和动力学进行研究，以阐明膜在不同条件下的粘度和弹性模数。这一研究结果将对聚合物薄膜在复合材料、粘合剂、包装、生物相容性材料和生物传感器中的应用产生重大影响。学生，包括来自代表人数不足的群体的学生，将在国家实验室接受使用国家或最先进的同步辐射x射线设备的培训。

Non-Technical AbstractMuch of the biological activity of cells takes place on membranes. Consequently, a focus of research on biosensors is the construction of artificial membranes supported on semiconductor surfaces. The goal of the present work is to investigate the structural and dynamic properties of such supported membranes using a sophisticated technique known as coherent x-ray scattering. The results of measurements will be used to construct hydrodynamic models of membrane motion and to determine the values of important physical parameters such as the surface tension, viscosity and elastic moduli. The research will begin on lipid bilayers supported on a substrate and probe the changes in their dynamics as membranes are freed from the substrate by adding intermediate cushioning layers such as cellulose films, or by tethering the membranes above the substrate with proteins. The results of this research will have significant impact on the application of polymer films in composites, adhesives, packaging, biocompatible materials, and biosensors. Students, including from underrepresented groups, will be trained in the use of state-or-the-art synchrotron x-ray facilities at national laboratories.Technical AbstractThis project will study the structure and dynamics of liquid interfaces including both polymeric fluid interfaces and lipid bilayers using grazing incidence x-ray scattering and x-ray Photon Correlation Spectroscopy (XPCS) which utilizes coherent x-ray beams. Coupled with theoretical treatments of viscoelastic hydrodynamics, this work will provide methods of analyzing the interface tension, viscosity and elastic moduli of thin liquid films. Anomalous dynamical behavior in the vicinity of the glass transition temperature for polymeric films will be examined. The work on polymers will provide the starting point for studies of the dynamical fluctuations in lipid bilayer membrane systems. Supported membranes in water on bare or cushioned substrates provide oriented films of sufficient surface area to study with techniques such as x-ray or neutron scattering, XPCS or neutron spin echo. The structure, conformation and dynamics of these layered systems will be studied to elucidate the viscosities and elastic moduli of membranes under various conditions. The results of this research will have significant impact on the application of polymer films in composites, adhesives, packaging, biocompatible materials, and biosensors. Students, including from underrepresented groups, will be trained in the use of state-or-the-art synchrotron x-ray facilities at national laboratories.