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Neutron reflectometry studies of the interactions of dendrimers with oppositely charged amphiphiles

Mercredi 5 février 2014 15:00 - Duree : 1 heure
Lieu : Seminar Room, ILL4, 1st floor, 6 rue Jules Horowitz, Grenoble

Orateur : Marianna YANEZ ARTETA (Physical Chemistry, Lund University, Lund, Sweden)

Neutron reflectometry (NR) in combination with other techniques has been employed to reveal the interactions of cationic poly(amidoamine) (PAMAM) dendrimers with sodium dodecyl sulfate (SDS) at liquid interfaces. PAMAM dendrimers are well-defined polymers with a hierarchical architecture which make them promising materials as nanocapsules and gene vectors. The dendrimers interact strongly in the bulk solution with the oppositely charged surfactant, forming complexes whose charge depends on the PAMAM/SDS ratio. At the silica-water interface, PAMAM generation 4 and 8 adsorb irreversibly on silica and SDS interacts with the preadsorbed layer of dendrimers. Exposure to low SDS concentrations results in swelling of the adsorbed layer, while the data recorded at high concentrations reveal surfactant aggregation around the polymer layer. The adsorption of surfactant is reversible upon rinsing although causes slight changes to the PAMAM monolayers. The adsorption from premixed dendrimer/surfactant solutions results in thick multilayers around the charge neutrality of the complexes and decreases when the bulk complexes have a net negative charge. At the air-water interface, there is a synergistic enhancement of adsorbed surfactant in the presence of PAMAM dendrimers. The NR data show that the well-defined hyperbranched structure and generation of the dendrimer have an effect on the structure and composition of the interfacial layers formed compared to other polyelectrolytes. The improved understanding of PAMAM/amphiphiles interactions at interfaces outlined in this work broadens the fundamental knowledge towards future dendrimer applications interacting with amphiphiles. Currently, we are investigating the interactions at the solid/liquid interface between PAMAM dendrimers and novel nucleic acid base surfactants (DLPNs), which have the ability to interact with nucleic acids such as DNA and RNA due to base pairing, an ability that PAMAM dendrimers do not have. By forming complexes between dendrimers and DLPNs we can obtain more effective vectors with capacity for molecular recognition without extensive synthesis.

Contact : sultan@ill.eu

Discipline évènement : (Physique)
Entité organisatrice : (ILL)
Nature évènement : (Séminaire)
Evènement répétitif : (General ILL Seminar - College 9)
Site de l'évènement : Polygone scientifique

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