Speaker:Wang Dapeng, Researcher, State Key Laborary of Polymer Physics and Chemistry

Date:May 8, 2019

Time:4:00 pm-5:00 pm

Location:Lecture Hall, F2, Institute of Crystal Materials, Central Campus

Sponsor:School of Chemistry and Chemical Engineering

Abstract:

Theoretical predictions have suggested that molecular motion at interfaces – which influences processes including heterogeneous catalysis, (bio)chemical sensing, lubrication/adhesion, and nanomaterial self-assembly – may be dominated by hypothetical “hops” through the adjacent liquid phase, where a diffusing molecule re-adsorbs after a given hop according to a probabilistic “sticking coefficient”. Here, we used 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 experienced multiple unproductive surface encounters before re-adsorption. An average of ~7 surface collisions was required for the repulsive surfaces, decreasing to ~2.5 for surfaces that were more attractive. The hops themselves were 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.

Recently developed single-molecule tracking techniques allow us to image millions of individual molecules dynamically at solid/liquid and liquid/liquid interfaces. These high-throughput single-molecule experiments go beyond understanding the average behavior of adsorbates and enable us to probe variability in surface chemistry, molecular conformations, and adsorbate dynamics. Making such measurements, we often find that the behavior is much richer and more interesting than conventional wisdom suggests. In this abstract, we demonstrated that a process of desorption—readsorption at interfaces can result in plenty of anomalous behaviors that can be quantitatively modeled by continuous time random walk statistics.

For more information, please visit:

http://www.view.sdu.edu.cn/info/1020/117518.htm

Edited by: Sun Yangyang