Ray Chad, Brown Jason R, Akhremitchev Boris B
Department of Chemistry, Duke University, Durham, North Carolina 27708, USA
Langmuir. 2007 May 22;23(11):6076-83. doi: 10.1021/la070131e. Epub 2007 Apr 18.
Force spectroscopy is a new and valuable tool in physical chemistry and biophysics. However, data analysis has yet to be standardized, hindering the advancement of the technique. In this article, treatment of the rupture forces is described in the framework of the Bell-Evans model, and the systematic errors associated with the tether effect for approaches that utilize the most probable, the median, and the mean rupture forces are compared. It is shown that significant systematic errors in the dissociation rate can result from nonlinear loading with polymeric tethers even if the apparent loading rate is used in the analysis. Analytical expressions for the systematic errors are provided for the most probable and median forces. The use of these expressions to correct the associated systematic errors is illustrated by the analysis of the measured rupture forces between single hexadecane molecules in water. It is noted that the measured distributions of rupture forces often contain high forces that are unaccounted for by theoretical models. Experimental data indicate that the most significant effect of the high forces "tail" is on the dissociation rate obtained from the median force analysis whereas the barrier width appears to be unaffected.
力谱学是物理化学和生物物理学中一种新的且有价值的工具。然而，数据分析尚未标准化，这阻碍了该技术的发展。在本文中，在贝尔 - 埃文斯模型的框架内描述了对断裂力的处理，并比较了与利用最可能、中位数和平均断裂力的方法相关的系链效应的系统误差。结果表明，即使在分析中使用表观加载速率，聚合物系链的非线性加载也可能导致解离速率出现显著的系统误差。为最可能力和中位数力提供了系统误差的解析表达式。通过分析水中单个十六烷分子之间测量的断裂力，说明了使用这些表达式校正相关系统误差的方法。需要注意的是，测量的断裂力分布通常包含理论模型无法解释的高力值。实验数据表明，高力“尾部”的最显著影响是对从中位数力分析获得的解离速率，而势垒宽度似乎不受影响。
