Développement d’une approche multi-échelle pour l'étude de la solubilité des flavonoïdes et leur assemblage avec les polymères

Abstract : Over the past few decades, flavonoids have become increasingly used in different food and non-food applications due to their important antioxidant activities. However, the solubilization, dispersion and stabilization of these molecules are variable and constitute a brake on their use in different formulations. The objective of this work is to overcome those limitations by understanding the interactions between these compounds and their environment without and with the add of polymers, by a multi-scale approach approach (molecular modeling and mesoscale modeling and experimental study). Initially, interactions between 3 flavonoids (quercetin, rutin and isoquercetin) in various organic solvents, were studied. The obtained results (mainly Flory Huggins parameter and radial distribution function RDF) showed that the B2 part common to the three flavonoids (For example Flory Huggins parameter values were close to 0.5 in the M2B2 and much more important in acetonitrile) is responsible for the miscibility behavior of the flavonoids in the solvent. DDFT simulations showed aggregation of quercetin in M2B2 against dispersion in acetonitrile. All these observations were confirmed experimentally (study of solubility and microscopic observations). Then, quercetin was studied in the presence of a biopolymer, PLGA in water. Nanoparticles were formed by varying the concentration of the various compounds and the lactic acid / glycolic acid ratio in the PLGA. The tools of molecular modeling and mesoscale modeling (calculation of the solubility parameter by molecular dynamics and observation of the dispersion or the phase separation by DDFT) as well as the experimental approach (DSC, MET ...) led us to the same conclusions. Indeed, the particle size increases with the concentration of PLGA and the rate of lactic acid in the polymer. Also the concentration of the emulsifier in the medium has an important role in the formation of PLGA-Q aggregates. The higher its concentration, the more difficult the formation of the particles as it affects the viscosity of the medium and consequently the diffusivity of the molecules in the water. All the results obtained by molecular modeling and by mesoscale modeling have been confirmed experimentally. We can therefore conclude that the methodology adopted in the simulations can be considered as a tool to help on predicting the behavior of flavonoids in different medium
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Theses
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http://docnum.univ-lorraine.fr/ulprive/DDOC_T_2017_0347_SLIMANE.pdf
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https://hal.univ-lorraine.fr/tel-01917032
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Submitted on : Friday, November 9, 2018 - 9:17:15 AM
Last modification on : Saturday, November 10, 2018 - 1:17:15 AM

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Manel Slimane. Développement d’une approche multi-échelle pour l'étude de la solubilité des flavonoïdes et leur assemblage avec les polymères. Ingénierie des aliments. Université de Lorraine, 2017. Français. ⟨NNT : 2017LORR0347⟩. ⟨tel-01917032⟩

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