STRUCTURE AND INTERACTIONS OF MODEL BIOMEMBRANES III

模型生物膜 III 的结构和相互作用

• 批准号: 6490044
• 负责人: JACOB N ISRAELACHVILI
• 金额: $ 24.02万
• 依托单位: UNIVERSITY OF CALIFORNIA SANTA BARBARA
• 依托单位国家: 美国
• 财政年份: 1992
• 资助国家: 美国
• 起止时间: 1992-05-01 至 2002-12-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6490044
• 关键词: artificial membranes; atomic force microscopy; bioengineering /biomedical engineering; biomaterial compatibility; biomaterial development /preparation; biomimetics; drug delivery systems; electron microscopy; fluorescence microscopy; intermolecular interaction; lipid bilayer membrane; mathematical model; membrane activity; membrane model; membrane proteins; membrane structure; molecular dynamics; molecular rearrangement; nanotechnology; protein protein interaction; scanning tunneling microscopy; selectins

We hypothesize that "softly supported" bilayers incorporating selectins are excellent in vitro models for Surface Force Apparatus (SFA) measurements of the 'rolling forces' between complementary surfaces expressing selectins and its ligands. Isolating the molecular features (static and dynamic forces, mobility, on and off rates, etc.) of the specific ligands and receptors that control cell-cell and cell-substrate adhesion is difficult in vivo, although necessary for determining the basic rules governing cell sorting, tissue differentiation, pathological deformations and growths, and the body's control of cell population size and location. In addition, the dynamics of specific adhesion, i.e., of receptor -ligand pairs, is essential for understanding the body's immune response and in the biomimetic construction of drug delivery systems. The specific systems to be examined include: (1) Measurement and characterization of biomolecular and biosurface interactions. The Surface Forces Apparatus (SFA), AFM, and optical microscopy will be employed to measure bilayer, membrane and specific protein (e.g., ligand-receptor) interactions of softly-supported bilayers and monolayers. Specific systems will include: (1) the dynamic interactions of P-selectin proteins with various ligands such as lipid bilayers exposing polysaccharide headgroups (selectins are an important family of adhesion and recognition proteins), (2) DNA-lipid biolayer interactions which are primarily important for DNA transfection agents such as DNA- encapsulating vesicle delivery systems; (3) comparing these interactions to PEG-tethered biotin-lipids and streptavidin, this being a genetic tethered system with strong ligand-receptor bonds of varying tether length. (2) Biomimetic construction of complex structures. We plan to determine optimal methods of initiating, limiting, and controlling vesicle aggregation to produce aggregates of defined size and composition by manipulating (i) ligand-receptor stoichiometry, (ii) ligand-receptor "on- rates" through control of electrostatic or steric repulsions induced by pH, divalent ions and (iii) bilayer-bilayer and vesicle-vesicle interactions through control of surface charge or polymeric steric layers, ionic strength, or divalent ions. We also will study metastable bilayer structures for use as generic encapsulating membranes. The systems will include (i) mixtures of saturated phospholipids, cholesterol and polymer lipid that form open discs, and (ii) mixtures of long and short chain phosphatidylcholines, that form bilayer discs at low temperatures but close to form vesicles at higher temperatures, and (iii) ethanol interdigitated bilayers of DPPC that also form temperature dependent discs.

我们假设包含选择素的“软支撑”双层是表面力仪（SFA）测量表达选择素及其配体的互补表面之间“滚动力”的优秀体外模型。尽管对于确定控制细胞的基本规则是必要的，但在体内分离控制细胞-细胞和细胞-基质粘附的特定配体和受体的分子特征（静态和动态力、移动性、开启和关闭速率等）是困难的分类、组织分化、病理变形和生长，以及身体对细胞群大小和位置的控制。此外，特异性粘附（即受体-配体对）的动力学对于理解人体的免疫反应和药物输送系统的仿生构建至关重要。要检查的具体系统包括：（1）生物分子和生物表面相互作用的测量和表征。表面力装置 (SFA)、AFM 和光学显微镜将用于测量软支撑双层和单层的双层、膜和特定蛋白质（例如配体-受体）相互作用。具体系统将包括：（1）P-选择素蛋白与各种配体的动态相互作用，例如暴露多糖头基的脂质双层（选择素是粘附和识别蛋白的重要家族），（2）DNA-脂质生物层相互作用，主要是对于 DNA 转染剂（如 DNA 封装囊泡递送系统）很重要； (3) 将这些相互作用与 PEG 系链的生物素-脂质和链霉亲和素进行比较，这是一个具有不同系链长度的强配体-受体键的遗传系链系统。 (2)复杂结构的仿生建造。我们计划确定启动、限制和控制囊泡聚集的最佳方法，以通过操纵（i）配体-受体化学计量，（ii）通过静电或空间控制控制配体-受体“结合速率”来产生指定大小和组成的聚集体。 pH、二价离子和 (iii) 通过控制表面电荷或聚合物空间层、离子强度或二价的双层-双层和囊泡-囊泡相互作用引起的排斥离子。我们还将研究用作通用封装膜的亚稳态双层结构。该系统将包括（i）形成开放盘的饱和磷脂、胆固醇和聚合物脂质的混合物，以及（ii）长链和短链磷脂酰胆碱的混合物，其在低温下形成双层盘，但在较高温度下接近形成囊泡，以及(iii) DPPC 的乙醇叉指双层也形成温度依赖性盘。