Objectif The objectives of the project are to prepare and characterise the structure of supermolecular complexes of natural polyelectrolyte polysaccharides with surfactants, proteins or aminoacids. Polyelectrolyte polysaccharides take their importance in the food, cosmetics and pharmaceutical industry from the fact that they easily form gels. They are used in a wide variety of applications ranging from beverage thickeners through superabsorbing materials to drug delivery systems. Temperature, pH and light sensitive gels - the latter can be made by incorporating photoactive proteins - are being actively investigated in several laboratories to produce new types of intelligent materials.The preparation and characterisation of gels remain hitherto, however, largely empirical. A better understanding of the parameters that govern their stability and phase behaviour is thus not only much needed but is also a great challenge in fundamental research that requires very special skills. The systematic investigation of the formation of the complexes of polyelectrolyte polysaccharides and the effect of temperature, ionic strength and nature of added salts or surfactants, on their phase behaviour and stability is thus a major part of the project.The formation of polyelectrolyte polysaccharide gels - in this case carrageenans - involves initially a thermoreversible, ion-induced conformational transition from a disordered state (coil) to an ordered state (helix) affecting individual molecules. Aggregation and network formation on a much larger scale then follow when the ionic strength is increased, for example. Interactions of the gels with surfactants lead to complex phase behaviour, including in some cases the formation of liquid crystalline phases, depending on aggregation or segregation properties of the components.The best way to obtain information about different levels of organisation in rather fragile structures like gels is to use scattering of light, X-rays and neutrons or ultrasonic methods. Some of these techniques rely on the use of large-scale facilities like synchrotron radiation and neutron sources, which are only available in a few places in the world.Knowledge about the structure of gels is much less advanced than that of the crystalline state and a major objective of the project is to develop theoretical concepts and models to describe network-surfactant and network-protein interactions.Scattering patterns of gels, which are obviously not well ordered structures, contain much less information than those of crystals. Whereas for crystalline systems the interpretation of diffraction patterns is by now largely a matter of routine, for systems like gels new modelling and data interpretation techniques in terms of meaningful structural parameters related to theoretical models, still have to be developed. Following the tradition of the teams involved in this aspect of the project, these techniques will be implemented in general user-friendly computer programs that are freely accessible on the Internet.It would certainly have been much more difficult to start such a complex project if the teams involved did not already have the close contacts that were made possible by a previous very successful collaboration funded by INTAS. One of the most positive aspects of the present project for the future is that it will give about ten bright young scientists from the different teams an opportunity to participate in advanced research at the pre- to postdoctoral level in collaboration with their colleagues from abroad. Programme(s) IC-INTAS - International Association for the promotion of cooperation with scientists from the independent states of the former Soviet Union (INTAS), 1993- Thème(s) 3 - Chemistry OPEN - OPEN Call Appel à propositions Data not available Régime de financement Data not available Coordinateur European Molecular Biology Laboratory Contribution de l’UE Aucune donnée Adresse Notkestrasse 85 22603 Hamburg Allemagne Voir sur la carte Coût total Aucune donnée Participants (4) Trier par ordre alphabétique Trier par contribution de l’UE Tout développer Tout réduire Catholic University of Leuven Belgique Contribution de l’UE Aucune donnée Adresse Celestijnenlaan 200F 3001 Leuven-Heverlee Voir sur la carte Coût total Aucune donnée Institute of Bioorganic Chemistry and Petrochemistry Ukraine Contribution de l’UE Aucune donnée Adresse Murmanska street, 1 02094 Kiev Voir sur la carte Coût total Aucune donnée M.V. Lomonosov Moscow State University Russie Contribution de l’UE Aucune donnée Adresse Voroviowy Gory 117234 Moscow Voir sur la carte Coût total Aucune donnée Russian Academy of Sciences Russie Contribution de l’UE Aucune donnée Adresse Leninski prospekt 59 117333 Moscow Voir sur la carte Coût total Aucune donnée
