Directed single molecule diffusion triggered by surface energy gradients

Pierre Burgos, Zhenyu Zhang, Ramin Golestanian, Graham J. Leggett, Mark Geoghegan

Research output: Contribution to journalArticlepeer-review

28 Citations (Scopus)


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.
Original languageEnglish
Pages (from-to)3235-3243
Number of pages9
JournalACS Nano
Issue number10
Publication statusPublished - 27 Oct 2009


  • single molecule
  • directed diffusion
  • self-assembled monolayer (SAM)
  • Chemical engineering
  • Chemical Engineering(all)


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