Incorporating DNA in a lamellar phase: A Flory model

Abstract:

Following an experimental work demonstrating that DNA pieces can be incorporated in large quantity in a neutral lamellar phase, we propose a theoretical model showing that finite-size rod-like particles can be incorporated in a lyotropic smectic-A phase with an interlamellar spacing smaller than the rod length. This model based on a Flory-type description on a lattice allowed us to calculate a ternary (rods/water/surfactant) phase diagram. We demonstrate that a particle-enriched lamellar phase and a particle-depleted lamellar phase can coexist. In the latter case the rods exhibit a long-range (nematic-like) orientational order. The predictions are in qualitative agreement with the experiments.