Laboratory of Biomechanics and Biomedical Engineering, Mechanical Engineering and Aeronautics Department, University of Patras, Patras 26504, Greece.
Colloids Surf B Biointerfaces. 2010 Jan 1;75(1):252-9. doi: 10.1016/j.colsurfb.2009.08.041. Epub 2009 Sep 3.
Atomic force microscopy (AFM) was used to measure the non-specific detachment force of single fibrinogen molecules from glass surfaces. The identification of single unbinding events was based on the characteristics of the parabolic curves, recorded during the stretching of protein molecules. Fibrinogen molecules were covalently bound to Si(3)N(4) AFM tips, previously modified with 3-aminopropyl-dimethyl-ethoxysilane, through a homobifunctional poly(ethylene glycol) linker bearing two hydroxysulfosuccinimide esters. The most probable detachment force was found to be 210 pN, when the tip was retracting with a velocity of 1400 nm/s, while the distribution of the detachment distances indicated that the fibrinogen chain can be elongated beyond the length of the physical conformation before detachment. The dependence of the most probable detachment force on the loading rate was examined and the dynamics of fibrinogen binding to the surface were found amenable to the simple expression of the Bell-Evans theory. The theory's expansion, however, by incorporating the concept of the rupture of parallel residue-surface bonds could only describe the detachment of fibrinogen for a small number of such bonds. Finally, the mathematical expression of the Worm-Like Chain model was used to fit the stretching curves before rupture and two interpretations are suggested for the description of the AFM curves with multiple detachment events.
原子力显微镜（AFM）被用于测量从玻璃表面脱离的单个纤维蛋白原分子的非特异性脱离力。单键解吸事件的识别是基于记录在拉伸蛋白质分子过程中得到的抛物线曲线的特征。纤维蛋白原分子通过带有两个羟基琥珀酰亚胺酯的同双官能聚乙二醇接头共价结合到先前用 3-氨丙基二甲基乙氧基硅烷修饰的 Si(3)N(4) AFM 尖端上。当尖端以 1400nm/s 的速度缩回时，发现最可能的脱离力为 210pN，而脱离距离的分布表明纤维蛋白原链可以在脱离之前延伸到物理构象的长度之外。研究了最可能的脱离力对加载速率的依赖性，并发现纤维蛋白原与表面的结合动力学适合于贝尔-埃文斯理论的简单表达。然而，通过结合平行残基-表面键断裂的概念对该理论进行扩展，只能描述少数这种键的纤维蛋白原的脱离。最后，使用蠕虫状链模型的数学表达式来拟合断裂前的拉伸曲线，并提出了两种解释来描述具有多个脱离事件的 AFM 曲线。
