Cellular adhesion is an intricate physical process controlled by ligand–receptor affinity, density, mobility, and external forces transmitted through the elastic properties of the cell. As a model for cellular adhesion we study the detachment of cell-sized liposomes and membrane-coated silica beads from supported bilayers using atomic force microscopy. Adhesion between the two surfaces is mediated by the interaction between the adhesive lipid anchored saccharides lactosylceramide and the ganglioside G_M3. We found that force–distance curves of liposome detachment have a very peculiar, partially concave shape, reminiscent of the nonlinear extension of polymers. By contrast, detachment of membrane coated beads led to force–distance curves similar to the detachment of living cells. Theoretical modelling of the enforced detachment suggests that the non-convex force curve shape arises from the mobility of ligands provoking a switch of shapes from spherical to unduloidal during detachment.

中文翻译：

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巨脂质体的分离-受体迁移率和膜形状的耦合。

细胞粘附是一个复杂的物理过程，受配体-受体亲和力，密度，迁移率和通过细胞弹性特性传递的外力控制。作为细胞粘附的模型，我们使用原子力显微镜研究了细胞大小的脂质体和支持的双层膜的二氧化硅膜珠的分离。两个表面之间的粘附是由粘附的脂质锚定糖乳糖神经酰胺和神经节苷脂G _M3之间的相互作用介导的。我们发现脂质体脱离的力-距离曲线具有非常特殊的，部分凹入的形状，让人联想到聚合物的非线性延伸。相比之下，膜包裹的珠子的分离导致力-距离曲线类似于活细胞的分离。强制脱离的理论模型表明，非凸力曲线的形状是由于配体的迁移而引起的，该配体在脱离过程中引起了从球形到非双倍体形状的转换。