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Confinement of dna in thin liquid films. Study of the electrostatic interactions and of the influence of condensing agents


Research objectives and content
There have been recent important advances, both theoretical and experimental, in the description of the aqueous solutions of polyelectrolytes. On another hand, DNA condensation, a very important process in the regulation of the genetic material, is probably controlled by a delicate balance involving electrostatic interactions. We plan to describe in a quantitative manner the electrostatic interactions in DNA aqueous solutions by studying solutions with and without condensing agents (salts, surfactants). We propose to confine the solutions in freely-suspended thin liquid films, and to measure the interaction forces between the film surfaces with a device called a 'thin film balance'. These forces reflect the structure of the solution due to the electrostatic. repulsions between the polymer chains. Independent classical X-ray scattering determination of the bulk solution's structure will be performed. The eventual effects of polymer confinement close to the surfaces will then be analysed. The structure of the surface monolayers will be determined independently by other methods involving the free surface of the solution: surface tension, ellipsometry, X-ray and neutron reflectivity. Special attention will be paid to the case of condensation with cationic surfactants, in view of the potential applications for cationic carriers in gene therapy.
Training content (objective, benefit and expected impact)
I will benefit greatly from learning the experimental techniques involved in the study, in particular, ellipsometry, thin film balance, X-ray and neutron reflectivity, and scattering techniques. Furthermore, biopolymer research is a field at the boundary between physical chemistry and biology, and will probably expand considerably in the coming years. The group of Dr. D. Langevin is participating in a cooperative research effort initiated in France in this area. I therefore expect to attend severa group meetings and meet a large number of French scientists. These connections will be useful for the future research that I would like to pursue in Germany. Links with industry / industrial relevance (22)
Our project is closely connected to gene therapy research. Many industrial companies are interested in this area (in France for instance Rhtne-Poulenc). Contacts with these companies will be made in relation to the proposed project.

Funding Scheme

RGI - Research grants (individual fellowships)


Batiment 510 Centre Universitaire Paris Sud
91405 Orsay