Europhys. Lett.
Volume 73, Number 4, February 2006
Page(s) 635 - 641
Section Interdisciplinary physics and related areas of science and technology
Published online 06 January 2006
Europhys. Lett., 73 (4), pp. 635-641 (2006)
DOI: 10.1209/epl/i2005-10425-3

Binding effects in multivalent Gibbs-Donnan equilibrium

M. Castelnovo1 and A. Evilevitch2

1  Laboratoire Joliot-Curie et Laboratoire de Physique, Ecole Normale Supérieure de Lyon - 46 Allée d'Italie, 69364 Lyon Cedex 07, France
2  Department of Biochemistry, Center of Chemistry and Chemical Engineering Lund University - P.O. Box 124, S-221 00 Lund, Sweden

received 1 August 2005; accepted in final form 14 December 2005
published online 6 January 2006

The classical Gibbs-Donnan equilibrium describes excess osmotic pressure associated with confined colloidal charges embedded in an electrolyte solution. In this work, we extend this approach to describe the influence of multivalent ion binding on the equilibrium force acting on a charged rod translocating between two compartments, thereby mimicking ionic effects on force balance during in vitro DNA ejection from bacteriophage. The subtle interplay between Gibbs-Donnan equilibrium and adsorption equilibrium leads to a non-monotonic variation of the ejection force as multivalent salt concentration is increased, in qualitative agreement with experimental observations.

82.60.Lf - Thermodynamics of solutions.
82.35.Rs - Polyelectrolytes.
82.39.Wj - Ion exchange, dialysis, osmosis, electro-osmosis, membrane processes.

© EDP Sciences 2006