Biophys J, January 2001, p. 161-168, Vol. 80, No. 1

Toroidal Condensates of Semiflexible Polymers in Poor Solvents: Adsorption, Stretching, and Compression

G. G. Pereira^* and D. R. M. Williams^*

 ^*Department of Applied Mathematics, Research School of Physical Sciences and Engineering, Australian National University, Canberra, Australian Capital Territory 0200, and  School of Chemistry, University of Sydney, New South Wales 2006, Australia

When a semiflexible polymer chain is placed in a poor solvent, or in the presence of condensing agents, a toroidal condensate can result. In typical experiments, these condensates are adsorbed to surfaces. Here we examine the changes that can occur when a toroid is adsorbed. We then examine the behavior of a toroid when stretched and identify two regimes: a weak stretching regime where the toroid deforms from a circle to an ellipse, and a strong stretching regime where a tether is pulled from the toroid. In the weak stretching regime, the force increases linearly with separation whereas in the strong stretching regime, the applied force is a constant. We then look at the case of a toroid compressed in the plane of the toroid. In this case the form of the force law depends on how strongly the toroid wets the surfaces. In general, an inverse square force law is found.

Biophys J, January 2001, p. 161-168, Vol. 80, No. 1
© 2001 by the Biophysical Society   0006-3495/01/01/161/08  $2.00