Simulations of Single-Molecule Friction at Hydrophilic Surfaces

亲水表面单分子摩擦的模拟

• 批准号: 35449642
• 负责人: Professor Dr. Roland Netz
• 金额: --
• 依托单位: Institut für Theoretische Physik
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2006
• 资助国家: 德国
• 起止时间: 2005-12-31 至 2014-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/35449642?language=en
• 关键词: Simulations; Single; Molecule; Friction; Hydrophilic

Adsorption free energies and friction effects of single peptide chains on different surfaces can be studied with the AFM. In the previous collaboration, the adsorption of a single spider-silk peptide chain on hydrophobic diamond was studied. In this proposal we concentrate on biologically more relevant hydrophilic surfaces with the goal to gain complete microscopic understanding of the involved kinetic effects. I) By a combination of extensive simulations and Fokker-Planck-modeling, we will extract the mobility of peptide chains on hydrophilic surfaces in the experimentally relevant linearresponse (i.e. low velocity) regime. This will allow us to quantify the mobility (or friction coefficient) of a single hydrogen bond, which is relevant for the kinetics of beta-sheet and alpha-helix formation. II) By applying normal forces to adsorbing polymers, we will formulate the nanoscopic version of Amonton’s law for single molecule friction in water. We will also vary the degree of hydrophilicity of the peptides, the surfaces and the chain length. III) We will study peptide-peptide friction effects with the goal to predict effective polymer mobilities in dense adsorbed layers. IV) We will study the rupture length dependence of adsorbed polymers for different polymer models, i.e. the cantilever height D* at which a polymer of contour length L spontaneously desorbs from an adsorbing surface.

利用原子力显微镜可以研究单链肽链在不同表面上的吸附自由能和摩擦效应。在之前的合作中，研究了单个蜘蛛丝肽链在疏水金刚石上的吸附。在这个建议中，我们专注于生物更相关的亲水性表面的目标，以获得完整的微观理解所涉及的动力学效应。I）通过广泛的模拟和Fokker-Planck模型的结合，我们将提取实验相关线性响应（即低速）状态下亲水表面上肽链的迁移率。这将使我们能够量化单个氢键的迁移率（或摩擦系数），这与β-折叠和α-螺旋形成的动力学有关。通过对吸附聚合物施加法向力，我们将为水中的单分子摩擦制定Amonton定律的纳米版本。我们还将改变肽的亲水性程度、表面和链长。III）我们将研究肽-肽摩擦效应，目标是预测致密吸附层中的有效聚合物迁移率。IV）我们将研究不同聚合物模型的吸附聚合物的断裂长度依赖性，即轮廓长度L的聚合物从吸附表面自发解吸的悬臂高度D*。