Indentation and adhesive probing of a cell membrane with AFM: Theoretical model and experiments
Indentation and adhesive probing of a cell membrane with AFM: Theoretical model and experiments
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DOI：
10.1529/biophysj.105.063826
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发表时间：
2005-11-01
影响因子：
3.4
通讯作者：
Discher, DE
中科院分区：
文献类型：
--
作者：
Sen, S;Subramanian, S;Discher, DE
在通过原子力显微镜 (AFM) 探测粘附和细胞力学时，膜的机械性能具有重要的作用（如果被忽视的话）。在这里，我们从理论上模拟了 AFM 尖端与细胞膜的接触，其中直接动机和数据来自原型配体-受体粘附实验。 AFM 尖端使用原型配体 SIRP α 进行功能化，然后用于探测红细胞上的天然受体 CD47。这种相互作用被证明是特定且典型的，并且在分离中也显示出一种可以延伸数百纳米的锯齿形破坏过程。这里的理论模型考虑了膜压痕以及尖端缩回时的膜延伸，结合了膜张力和弹性以及 AFM 尖端几何形状和随机破坏。重要的是，压痕深度最初被证明与膜张力成正比，并且不遵循标准赫兹模型。分离的计算证实了由膜张力设定的膜延伸数百纳米的非周期性破坏。因此，膜的机械性能明显影响细胞的 AFM 探测，包括单分子粘附实验。
In probing adhesion and cell mechanics by atomic force microscopy (AFM), the mechanical properties of the membrane have an important if neglected role. Here we theoretically model the contact of an AFM tip with a cell membrane, where direct motivation and data are derived from a prototypical ligand-receptor adhesion experiment. An AFM tip is functionalized with a prototypical ligand, SIRP alpha, and then used to probe its native receptor on red cells, CD47. The interactions prove specific and typical in force, and also show in detachment, a sawtooth-shaped disruption process that can extend over hundreds of nm. The theoretical model here that accounts for both membrane indentation as well as membrane extension in tip retraction incorporates membrane tension and elasticity as well as AFM tip geometry and stochastic disruption. Importantly, indentation depth proves initially proportional to membrane tension and does not follow the standard Hertz model. Computations of detachment confirm nonperiodic disruption with membrane extensions of hundreds of nm set by membrane tension. Membrane mechanical properties thus clearly influence AFM probing of cells, including single molecule adhesion experiments.