Le LIBio propose une offre de thèse en collaboration avec l'Université de Mahidol (Thaïlande, The Department of Chemistry of the Faculty of Science of Mahidol University) et le LCPM intitulée "Design of stable polysaccharide vectors by enzymatic modification / cross-linking of coacervates".
Voir l'offre sur le site de l'ABG
Description du sujet :
Electrostatic complexes are good candidates for the development of particles that can be used as vectors of active ingredients due to their versatility. Many systems can indeed be obtained in terms of structure, sizes and properties. Nevertheless, their main limitation is related to their low colloidal stability according to physico-chemical conditions (pH in particular). A strategy studied in the literature consists of cross-linking the complex once it is formed, which is usually carried out by a chemical pathway. Another possible but still little reported crosslinking pathway to obtain a particle with increased stability is the enzymatic pathway.
The envisaged system consists of the enzymatic cross-linking of a particulate electrostatic complex (nano or micro) formed between two agro-based polysaccharides.
Polysaccharides are well known to form colloidal objects (including coacervates) by electrostatic interactions. A coacervate being stable only for a fairly short time (because of coalescence phenomena taking place), an enzymatic cross-linking step should increase the stability of the complexes.
The three objectives addressed during this thesis are:
1) How to crosslink a polysaccharide coacervate via enzymatic catalysis in order to limit the use of chemical crosslinking agent? This part will be investigated by scientific partners from UL, LIBio and LCPM.
2) Can we rationalize the properties of the particles formed (size, polarity, porosity, stability...)? In other words, is it possible to formulate "tailored" vectors specifically adapted for an active ingredient and / or an application (introduce new functions, control disassembly / erosion of the vector, create porosity via physico-chemical stimulation). This part will be investigated by scientific partners from UL and MU.
3) An in-depth study of the encapsulation efficiency according to the morphology of the vector, the overall stability of the colloidal system as well as the release of the active ingredient under specific conditions will be conducted. In vitro tests will be set up according to the chosen target. This part will be investigated by scientific partners from UL and MU.
This project focuses on the formulation of innovative vectors whose constituents are exclusively derived from bioresources (see agroresources, food or co-products) obtained by gentle means (no "energy-intensive" shear processes, privileged enzymatic processes) stable because cross-linked by enzymatic means, with modular properties (size, structure, functions) to best adapt to an active ingredient and a given application. All the products and processes used are widely available and already used in industrial processes (especially food) making it possible to envisage from the outset an industrial potential of such a system.
In addition, the mastery of the properties of the vectors formed will require a detailed understanding of the interactions involved, a thorough characterization of the systems formed and the elucidation of the mechanisms governing the structuring of such systems.
LIBio and LCPM (France) will be in charge of developing the modification of polysaccharides (year n°1, month n°1 to 6), the development of vectors and encapsulation (year n°2, month n°13 to 18 and n°25 to 32). The Department of Chemistry of the Faculty of Science of Mahidol University (Thailand) will be in charge of the study of the formation of polyelectrolyte complexes from native or modified polysaccharides (year n°1, months n°7 to 12), as well as studies of kinetics of release of active molecules (year n°2, months n°19 to 24). Months n°33 to 36 will be devoted to the compilation of all the results, the finalization of certain publications and the writing of the thesis manuscript. Overall, the recruited PhD student will spend 24 months at the University of Lorraine (France) and 12 months at Mahidol University (Thailand).
Contact : Jordane Jasniewski