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Soft Matter and Biological Physics

Eur. Phys. J. E 4, 115-120

Structure factor of a lamellar smectic phase with inclusions

P. Sens1 and M.S. Turner2.

1  Institut Charles Sadron, 6 rue Boussingault, 67083 Strasbourg Cedex, France
2  Rockefeller University, New York, NY 10021 USA and Department of Physics, Warwick University, Coventry, CV4 7AL, UK


(Received 10 March 2000 and Received in final form 30 August 2000)

Motivated by numerous X-ray scattering studies of lamellar phases with membrane proteins, amphiphilic peptides, polymers, or other inclusions, we have determined the modifications of the classical Caillé law for a smectic phase as a function of the nature and concentration of inclusions added to it. Besides a fundamental interest on the behavior of fluctuating systems with inclusions, a precise characterization of the action of a given protein on a lipid membrane (anchoring, swelling, stiffening ...) is of direct biological interest and could be probed by way of X-ray measurements. As a first step we consider three different couplings involving local pinching (or swelling), stiffening or curvature of the membrane. In the first two cases we predict that independent inclusions induce a simple renormalization of the bending and compression moduli of the smectic phase. The X-ray experiments may also be used to probe correlations between inclusions. Finally we show that asymmetric coupling (such as a local curvature of the membrane) results in a modification of the usual Caillé law.

87.22.Bt - Membrane and subcellular physics and structure.
82.65.Dp - Thermodynamics of surfaces and interfaces.
82.70.-y - Disperse systems.

© EDP Sciences, Società Italiana di Fisica, Springer-Verlag 2001