DOI: 10.1209/epl/i2001-00412-2


Europhys. Lett., 55 (2) , pp. 294-300 (2001)

Direct observation of DNA molecules in a convection flow of a drying droplet

S. S. Abramchuk¹, A. R. Khokhlov¹, T. Iwataki², H. Oana³ and K. Yoshikawa<sup>3

1</sup>  Institute of Organoelement Compounds, Russian Academy of Sciences Vavilova St. 28, Moscow 117813, Russia
²  Graduate School of Human Informatics, Nagoya University Nagoya 464-8601, Japan
³  Department of Physics, Graduate School of Science, Kyoto University, CREST Kyoto 606-8502, Japan

(Received 21 July 2000; accepted in final form 3 May 2001)

Abstract
The motion of single T4 DNA molecules (166 kilo-base pairs) was studied by fluorescence microscopy in a drying droplet of polyethylene glycol (PEG) solution on a glass surface. An ordered flow was observed in the vicinity of the droplet contact line. A high stretching of the DNA molecules was found at the droplet periphery, whereas in its central part the DNA molecules were in a random coil state. With the increase of PEG concentration, individual DNA molecules show collapse transition directly from the stretched conformation after the formation of nuclei at the ends of the chain. Without PEG all the DNA molecules were in a random coil state and slowly diffused to the droplet boundary. They were trapped in a narrow region near the contact line.

PACS
87.14.Gg - DNA, RNA.
87.15.He - Dynamics and conformational changes.
87.15.La - Mechanical properties.


© EDP Sciences 2001