Morphology and Rheology of Biological Complex Fluids in Confined Geometry

利用中子和X射线反射率、显微干涉和胶体探针显微镜等多种表面敏感技术，设计并研究了模拟细胞表面糖环典型物理性质和功能的固体表面软界面。人工糖卡的设计有：1.通过在支撑膜上重组脂聚合物(具有不同尺寸的PEO-头基的磷脂)和糖化脂质(神经节苷脂和脂质偶联的Lewis X因子)，2.通过表面接枝多糖(硫酸乙酰肝素和透明质酸)和将凝集素(作为选择素的模型)偶联到聚合物链上。该项目的一个主要目标是了解通过接枝密度、糖杯的结构和动力学来控制细胞-细胞黏附和生物功能化(纳米到微米)胶体颗粒(作为吞噬体)的结合。解决这个问题的一种方法是测量大分子配体与埋藏在表面嫁接的糖杯模型中的受体(例如，脂联选择素或凝集素)的结合动力学(例如，通过应用中子反射率)。第二种策略是用新开发的基于磁镊子的胶体力显微镜来测量粘附力。通过施加磁力脉冲序列和微干涉分析力-偏转曲线，测量了不同配体(RGC配体、Lewis X因子和吸附的纤维连接蛋白)修饰的磁珠相互作用势的时间演化。这些研究与Valérie MarchiArtzner的一个项目密切相关，该项目是通过RGD配体或Lewis因子的功能化来调节细胞对囊泡的摄取。

Soft interfaces on solid surfaces mimeticking typical physical properties and functions of glycocalices of cell surfaces are designed and studied by various surface sensitive techniques including neutron and X-ray reflextivity, micro-interferometry and colloidal probe microscopy. Artificial glycocalices are designed: 1. by reconstitution of lipopolymers (phospholipids with PEO-headgroups of various size) and glycosilated lipids (gangliosides and lipid-coupled Lewis X factors) in supported membranes, 2. by surface grafting of polysaccharides (heparan sulfate and hyaluronic acid) and coupling of lectins (as model of selectins) to polymer chains. One major objective of the project is to understand the control of cell-cell adhesion and the binding of biofunctionalized (nano- to micrometer) colloidal particles (acting as phagosomes) by the grafting density, the structure and dynamics of the glycocalix. One approac to this problem is the measurement of the binding kinetics of macromolecular ligands to receptors (e.g. lipid coupled selectins or lectins) buried within the surface grafted glycocalix models (e.g. by application of neutron reflectivity). A second strategy is to measure adhesion forces by a newly developed colloidal force microscopy based on magnetic tweezers. The time evolution of the interaction potential of magnetic beads functionalized by attachment of various ligands (RGDligands, Lewis X factor od adsorbed fibronectin) is measured by application of magnetic force pulse sequences and analysis of the force-deflection curves through microinterferometry. These studies are closely related to a project on the regulation of vesicle uptake by cells through functionalization with RGD-ligands or Lewis factors by the group of Valérie MarchiArtzner.