Wang Dapeng, Wu Haichao, Schwartz Daniel K
State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022, People's Republic of China.
Department of Chemical and Biological Engineering, University of Colorado Boulder, Boulder, Colorado 80309, USA.
Phys Rev Lett. 2017 Dec 29;119(26):268001. doi: 10.1103/PhysRevLett.119.268001.
Theoretical predictions have suggested that molecular motion at interfaces-which influences processes including heterogeneous catalysis, (bio)chemical sensing, lubrication and adhesion, and nanomaterial self-assembly-may be dominated by hypothetical "hops" through the adjacent liquid phase, where a diffusing molecule readsorbs after a given hop according to a probabilistic "sticking coefficient." Here, we use three-dimensional (3D) single-molecule tracking to explicitly visualize this process for human serum albumin at solid-liquid interfaces that exert varying electrostatic interactions on the biomacromolecule. Following desorption from the interface, a molecule experiences multiple unproductive surface encounters before readsorption. An average of approximately seven surface collisions is required for the repulsive surfaces, decreasing to approximately two and a half for surfaces that are more attractive. The hops themselves are also influenced by long-range interactions, with increased electrostatic repulsion causing hops of longer duration and distance. These findings explicitly demonstrate that interfacial diffusion is dominated by biased 3D Brownian motion involving bulk-surface coupling and that it can be controlled by influencing short- and long-range adsorbate-surface interactions.
理论预测表明，界面处的分子运动——其影响包括多相催化、（生物）化学传感、润滑与粘附以及纳米材料自组装等过程——可能由通过相邻液相的假设性“跳跃”主导，其中扩散分子在给定跳跃后根据概率性“粘附系数”重新吸附。在此，我们使用三维（3D）单分子追踪来明确可视化人血清白蛋白在固液界面处的这一过程，该界面会对生物大分子施加不同的静电相互作用。从界面解吸后，分子在重新吸附之前会经历多次无效的表面碰撞。对于排斥性表面，平均需要大约七次表面碰撞，而对于吸引力更强的表面，这一数字降至大约两点五次。跳跃本身也受到长程相互作用的影响，静电排斥增加会导致持续时间和距离更长的跳跃。这些发现明确表明，界面扩散由涉及本体 - 表面耦合的有偏三维布朗运动主导，并且可以通过影响短程和长程吸附质 - 表面相互作用来控制。
