Confinement-induced phase transition in a DNA-lipid hydrated complex
Instituto de Física, Universidade de São Paulo - Rua do Matão Travessa R Nr. 187, Brasil
2 Université de Bordeaux, Centre de recherche Paul-Pascal, CNRS - 115 avenue du Docteur-Schweitzer, F-33600 Pessac, France, EU
Accepted: 7 July 2010
We study the effect of the soft confinement by fluid lipid bilayers on the spatial organisation of DNA molecules in a DNA-zwitterionic lipid hydrated lamellar complex. The confinement is increased by dehydrating the complex in a controlled way, which leads to a decrease of the water channel thickness separating the periodically stacked bilayers. Using grazing-incidence small-angle X-ray scattering on an oriented thin film, we probe in situ as dehydration proceeds the structure of the DNA-lipid complex. A structural phase transition is evidenced, where an apparently disordered phase of DNA rods embedded within the one-dimensionally ordered lipid lamellar phase observed at high hydration is replaced by a 2D hexagonal structure of DNA molecules intercalated between the lipid bilayers.
PACS: 82.70.-y – Disperse systems; complex fluids / 68.18.Jk – Phase transitions in liquid thin films / 87.15.-v – Biomolecules: structure and physical properties
© EPLA, 2010