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arXiv 1306.5738cond-mat.soft
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Polymer吸附过程中长程跃迁的单分子观测

Single-Molecule Observation of Long Jumps in Polymer Adsorption

Changqian Yu, Juan Guan, Kejia Chen, Sung Chul Bae, Steve Granick

摘要:

吸附到最初裸露的表面上的单分子荧光成像表明,聚合物链不需要本地化后立即到达。在一个系统中优化,目前有限的吸附位点(石英表面,聚乙二醇(PEG)暴露在水溶液中,pH = 8.2),我们发现,一些链扩散回本体溶液中,并重新吸附在一定的距离,有时多次之前,要么本地化在一个稳定的位置,否则扩散到本体溶液。这种表面扩散机制比经典模型要快得多,在经典模型中,吸附的聚合物在表面上爬行,而整个分子保持吸附。具有跳跃的轨迹遵循具有极限斜率-2.5的步长的截断Levy分布,这与我们观察到的时间内定义明确的快速表面扩散系数一致。

英文摘要:

Single-molecule fluorescence imaging of adsorption onto initially-bare surfaces shows that polymer chains need not localize immediately after arrival. In a system optimized to present limited adsorption sites (quartz surface to which polyethylene glycol (PEG) is exposed in aqueous solution at pH = 8.2) we find that some chains diffuse back into bulk solution and re-adsorb at some distance away, sometimes multiple times before either they localize at a stable position or else diffuse away into bulk solution. This mechanism of surface diffusion is considerably more rapid than the classical model in which adsorbed polymers crawl on surfaces while the entire molecule remains adsorbed. The trajectories with jumps follow a truncated Levy distribution of step size with limiting slope -2.5, consistent with a well-defined, rapid surface diffusion coefficient over the times we observe.

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