Nouveaux systèmes micellaires intelligents à partir d'huile de lin (synthèse, comportements physico-chimiques et encapsulation)

Les micelles apparaissent comme prometteuses dans le domaine de la vectorisation de médicaments. Afin d améliorer leur biocompatibilité nous nous intéressons ici à des synthèses originales de copolymères amphiphiles comportant un bloc hydrophobe lipidique biosourcé. Un polymère intelligent constitue le bloc hydrophile. L huile de lin subit une modification chimique afin d introduire un site amorceur de polymérisation. Le bloc hydrophile est alors ajouté par polymérisation contrôlée. Deux copolymères sont obtenus, le lipide-b-poly(acide acrylique), pH-sensible et le lipide-b-poly(2-isopropyl-oxazoline), thermo-sensible. Une caractérisation physico-chimique complète révèle des concentrations micellaires critiques basses et des micelles de 10 nm. Un système mixte est préparé par mélange des deux copolymères. L étude de ce système prouve une sensibilité aux deux stimuli. Afin d améliorer la stabilité des micelles, nous proposons la photo-réticulation des insaturations de la chaîne lipidique.Small micellar systems seem to be really promising candidates for drug delivery applications. In order to improve the bio-assimilation of our system, the original synthesis of amphiphilic copolymers from linseed oil is carried out. First, linseed oil is chemically modified in order to introduce a polymerization initiating site. Then, the lipoinitiator is engaged in the controlled polymerization of the hydrophilic block. Two amphiphilic copolymers are obtained through this strategy: a pH-sensitive lipid-b-poly(acrylic acid), and a thermo-sensitive lipid-b-poly(2-isopropyl-oxazoline). Both present a low critical micellar concentration and form small micelles (~10 nm). By mixing both copolymers, mixed micelles responding to both stimuli were obtained. In order to improve the system s stability, the photo-cross-linking of the lipidic double bonds in the micelle s core is finally realized.ROUEN-INSA Madrillet (765752301) / SudocSudocFranceF

Solvent-polymer interactions in associative polymer/aqueous media systems

International audienceLight scattering measurements in the dilute regime (C < C*) of the amphiphilic hydrophobically modified hydroxyethyl cellulose (HMHEC) have shown a metastable equilibrium of solubility in pure water. As a consequence such ageing solutions present a great instability and in severe conditions of added NaCl or temperature, a demixion has been evidenced. In a more concentrated range of concentration, aqueous solutions of HMHEC possess higher viscosity than HEC precursor due to intermolecular hydrophobic associations. But in a 1M NaCl/ethanol mixture this effect is greatly weakened

Functionalized polysaccharides with aminoguaiacol : a competition between associative behavior and antibacterial and antioxidant activities

International audienc

Self-organization of Water Soluble and Amphiphile Crosslinked Carboxymethylpullulan

International audienceThe soluble state of amphiphile and crosslinked derivatives of carboxymethylpullulan was investigated by physicochemical analyses. This soluble state also called infinite sol was obtained from hydrogels after a short-time temperature treatment. The analyses show a large distribution in size for the species in solution (from some nanometers to some micrometers). Furthermore, they also reveal the presence of hydrophobic associations (intra and/or intermolecular) in addition to the chemical links. The nature of these hydrophobic interactions will depend on the polymer concentration and on the solvent used

Hydrogels Based on Polysaccharides Grafted Ferulic Acid: A Biomimetic Approach

International audienc

Hyaluronic Acid Functionalization with Jeffamine® M2005: A Comparison of the Thermo-Responsiveness Properties of the Hydrogel Obtained through Two Different Synthesis Routes

International audienceHyaluronic acid (HA) of different molar masses (respectively 38,000, 140,000 and 1,200,000 g.mol−1) have been functionalized with a commercial poly(etheramine), Jeffamine® M2005, in order to devise physical thermo-responsive hydrogels. Two routes have been studied, involving the use of either water for the first one or of N,N′-Dimethylformamide (DMF), a polar aprotic solvent, for the second one. In the case of the water route, the reaction was performed using a mixture of N-(3-Dimethylaminopropyl)-N′-ethylcarbodiimide (EDC) and N-hydroxysuccinimide (NHS) as coupling reagents. The reaction was optimized while making sure no free M2005 remained in the final material, leading to M2005 grafting degrees of about 4%, which enabled the formation of hydrogels by increasing the temperature. In the case of the organic solvent route, propylphosphonic anhydride T3P® was used as a coupling reagent in DMF, resulting in a M2005 grafting degree of around 8% with better thermo-responsive properties of HA-g-M2005 compared to those obtained when the reaction was performed in water. However, the reaction systematically led to covalent cross-linking in the case of the HA, with the highest starting molar masses resulting in a very different rheological behaviour and with higher gel strength retaining thermo-responsive behaviour but being only poorly soluble in water

pH-dependent stability of scleroglucan borate gels

International audienceScleroglucan, a neutral exopolysaccharide, forms strong physical gels by crosslinking with borate anions, and undergoes a conformational transition at pH > 13 (triple-helix to coil). A study of stability of scleroglucan/borate gels has been carried out over a wide range of pH and we have clearly observed a pH-dependence on the structure of these systems. The gel is dissolved in very alkaline media due to the conformational transition of scleroglucan and in acidic media, in agreement with thermodynamical competition between dissociation constant of boric acid and complexation constant of scleroglucan/borate system. Influence of polymer and borax concentrations have been also studied and it appeared that erosion of these matrices could be easily controlled as a function of the density of the network and pH. The pH-dependence of scleroglucan/borate gels could be used for controlling the release of macromolecular active substances

Polyelectrolyte complexes of hyaluronic acid and diethylaminoethyl dextran: Formation, stability and hydrophobicity

International audienc

Effect of carboxymethyl groups on degradation of modified pullulan by pullulanase from Klebsiella pneumoniae

International audienc