Thermal separation: Interplay between the soret effect and entropic force gradient

Yusuke T. Maeda, Axel Buguin, Albert Libchaber

Research output: Contribution to journalArticlepeer-review

75 Citations (Scopus)


Thermophoresis, the Soret effect, depletes a high concentration of a polyethylene glycol polymer solution from the hot region and builds a concentration gradient. In such a solution, solutes of small concentration experience thermophoresis and polyethylene glycol concentration-dependent restoring forces. We report that by using focused laser heating and varying the polyethylene glycol concentration one observes geometrical localizations of solutes like DNA and RNA into patterns such as a ring. For DNA up to 5.6 kbp, the ring size decreases following a behavior analogous to a gel electrophoresis separation. Above 5.6 kbp, the ring diameter increases with the DNA length. Mixtures of DNA and RNA can be separated as well as different RNA lengths. Separation of colloids is also observed. The experiments might be relevant for the separation of small RNA ribozymes in an early stage of life.

Original languageEnglish
Article number038301
JournalPhysical review letters
Issue number3
Publication statusPublished - Jul 11 2011
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • General Physics and Astronomy


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