Directed Single Molecule Diffusion Triggered by Surface Energy Gradients

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• 作者：Pierre Burgos ; Zhenyu Zhang ; Ramin Golestanian ; Graham J. Leggett ; Mark Geoghegan
• 刊名：ACS Nano
• 出版年：2009
• 出版时间：October 27, 2009
• 年：2009
• 卷：3
• 期：10
• 页码：3235-3243
• 全文大小：529K
• 年卷期：0
• ISSN：1936-086X

文摘

We demonstrate the diffusion of single poly(ethylene glycol) molecules on surfaces which change from hydrophilic to hydrophobic over a few micrometers. These gradients in surface energy are shown to drive the molecular diffusion in the direction of the hydrophilic component. The polymer diffusion coefficients on these surfaces are measured by fluorescence correlation spectroscopy and are shown to be elevated by more than an order of magnitude compared to surfaces without the surface energy gradient. Along the gradient, the diffusion is asymmetric, with diffusion coefficients ∼100 times greater in the direction of the gradient than orthogonal to it. This diffusion can be explained by a Stokes−Einstein treatment of the surface-adsorbed polymer.