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Rozprawy doktorskie na temat "Chitosane – Propriétés physico-chimiques":
Hajjali, Hassan. "Assemblage nanoparticules lipidiques solides-polysaccharide : étude des propriétés physico-chimiques pour la vectorisation d’un polyphénol". Thesis, Université de Lorraine, 2015. http://www.theses.fr/2015LORR0210/document.
This work deals with the design of a lipo-polysaccharidic system as a micrometric assembly between solid lipid nanoparticles (SLNs) and a biopolymer. The aim is to formulate a vector can: carry a hydrophobic active molecule, resist to gastric conditions, and allow a controlled release in specific conditions. Choosing the active molecule is carried on a polyphenol, curcumin, for its antioxidant and anti-inflammatory activities. Being hydrophobic, curcumin was encapsulated in shea butter nanoparticles, which is a natural lipid and solid at room temperature. Lipid nanocarriers are not resistant to gastric conditions; the nanoparticles have been included in a chitosan matrix in the form of a micrometric assembly controlled by electrostatic interactions. This natural polymer, positively charged due to the presence of amine groups, is resistant to attack by gastric enzymes and has specific interaction with the intestinal mucosa and in particular the mucin which can be useful as a carrier for curcumin in colon targeted drug delivery. The first part of this study focused on shea butter–curcumin system with the absence of chitosan. The effect of polyphenols on the lipid crystallization was studied. The influence of the composition of the ternary mixture (shea butter, surfactant, water) on the properties of the nanoparticles was then investigated by using the response surface methodology. This helped to control the size of SLNs and then to show the influence of particle size on the encapsulation efficiency of curcumin. The second part focuses on the assembling between the nanoparticles and chitosan. Micrometric particles were obtained through electrostatic interactions between SLNs encapsulated curcumin and chitosan
Aljawish, Abdulhadi. "Fonctionnalisation enzymatique de chitosane par des composés phénoliques : évaluation des propriétés biologiques et physico-chimiques de ces nouveaux biopolymères". Thesis, Université de Lorraine, 2013. http://www.theses.fr/2013LORR0089/document.
Oxidation of ferulic acid and its ester (ethyl ferulate) by Myceliophtora thermophila laccase has been studied in aqueous medium under mild experimental conditions (30°C and pH 7.5) as a green process to synthesize natural neo-molecules. Enzymatic oxidation led to colored and colorless intermediaries for ferulic acid and ethyl ferulate, respectively. Additionally, ethyl ferulate was oxidized faster than ferulic acid. This procedure has led to dimeric major products with MM = 443 g/mol and MM = 386 g/mol for ethyl ferulate and ferulic acid, respectively. New synthesized molecules demonstrated important antioxidants properties with weak antibacterial and cytotoxic properties. With insoluble chitosan particles in the reaction medium, laccase was protected from inhibition due to oxidation products and the polymerization degree of these products was checked. In addition, the oxidation products reacted with the free NH2 groups forming covalent bonds of Schiff base type (C=N) at C-2 region. The majority of the oxidation products grafted onto chitosan was of dimeric form. This procedure led to colored and colorless chitosans by ferulic acid and ethyl ferulate, respectively, with new properties due to grafting of phenolic compounds. These chitosan derivatives presented interesting functional properties such as antioxidant, physico-chemical (thermal stability) and biological (cell adhesion) as well as the preservation of antibacterial properties of native chitosan
Hammi, Nisrine. "Nanomatériaux structurés et multifonctionnels à base de chitosane : synthèses et applications". Thesis, Lille 1, 2020. http://www.theses.fr/2020LIL1R048.
The use of petroleum oils and other non-renewable carbon resources generates a considerable amount of waste, with a negative impact on the environment and health. As a result, the search for bio-based materials to replace petroleum-based materials has grown in the recent years. In this thesis, we studied the properties of chitosan, an aminocarbohydrate polysaccharide obtained by deacetylation of chitin, to structure the matter at the nanometric scale.We present a new and simple method for incorporating endogenous nano-objects into polysaccharide films. Supramolecular chemistry based on self-assembly of polysaccharides associated with sol-gel polymerization has thus made it possible to convert soluble precursors of chitosan and metal alkoxides into films consisting of nanostructured metal oxide clusters and chitosan. A wide range of simple, binary and ternary metal oxides have been successfully incorporated into bioplastics. The multifaceted use of these films has been demonstrated by transforming them under soft heat treatment into partially oxidized metal oxide-chitosan composites or by disolving them in aqueous conditions to produce stable, water dispersed metal oxide nanoparticles. The usefulness of these functional films has been demonstrated as antimicrobial material.We have also demonstrated an interesting structuring effect of these polysaccharides during the growth of porous coordination polymers. We studied the growth of HKUST-1 and ZIF-8 phases in a colloidal solution of chitosan biopolymers of different molecular weight and under various reaction conditions. In addition to preparing nanostructured polysaccharide-MOF hybrids with hierarchical porosity, we also succeeded in shaping the materials into flexible films, porous monoliths and self-supporting microspheres. Evaluation of the removal of Congo Red dye in water revealed that the chitosan-MOF hybrids outperform the pure phases (microporous MOF and chitosan).The chelating properties of chitosan make it a suitable precursor for the immobilization of metallic species in a carbonaceous matrix. Metal-carbon composites derived from chitosan have been prepared. Attractive physico-chemical properties, among high specific surface area, uniform metal dispersion, and existence of active nitrogen species, have been obtained. Due to the structuring effect of chitosan towards metal alkoxide precursors, a set of crystalline metal oxides comprising clusters of titanium dioxide, germanium oxide and iron oxide were obtained in situ in a nitrogen-doped carbon skeleton formed.Finally, we studied the preparation of catalysts for the hydrogenation of unsaturated compounds such as quinolines, alkynes and alkenes. Copper nanoparticles supported on nitrogen-doped carbon were prepared by pyrolysis of a mixture generated from copper (II) nitrate in an aqueous solution of melamine and chitosan. EDTA was also introduced to improve the dispersion of Cu nanoparticles during synthesis. The optimal catalyst CuNC-1-700 shows good catalytic performance for the studied reactions
Hasan, Mahmoud. "Nanovectorisation de la curcumine sous forme liposomale : interactions biomolécule / membrane, transferts et cytotoxicité dans des systèmes in vitro". Thesis, Université de Lorraine, 2015. http://www.theses.fr/2015LORR0314.
Curcumin, a yellow lipid-soluble natural pigment, a hydrophobic polyphenol derived from the rhizome of Curcuma longa, has been identified as the active principle of turmeric. Curcumin has already become a research focus due to its numerous biological and pharmacological benefits such as antioxidant, antitumor, anti-inflammatory, antimicrobial properties and other desirable medical benefits. However, due to its low absorption, the poor bioavailability of curcumin limits its clinical use. The objective of this work has focused on the study of the physicochemical properties of this molecule encapsulated in form of liposome. Different formulations of nanocarriers prepared from polar lipids more or less rich in polyunsaturated fatty acids with variable long chain, derived from vegetable or marine source, have been used to modify liposomes membrane fluidity. These works have allowed to optimize the encapsulation efficiency of the curcumin and to study its bioavailability and cytotoxicity effects on different cell lines (MCF7, embryonic cortical neurons). The results show significant effects when using nanoliposomes formulated with marine lecithin, protected by chitosan as the coating polymer. The physico-chemical analyses of the size by light scattering (Zetasizer, NanoSight), the stability (measurement of the size and the electrophoretic mobility), the structure by transmission electron microscopy and the release of the encapsulated molecule, allowed to better understand the effects of polymer-phospholipid interactions and the release of encapsulated curcumin in drastic environmental conditions of gastric and intestinal digestion. A multiscale characterization is proposed in order to improve the understanding of the various properties of the active agent (curcumin) and the nanovector, as well as the possible interactions occuring between them. The techniques used are Fourier Transform Infrared Spectroscopy (FTIR), X-rays, Rheometer and Transmission Electron Microscopy
Karaki, Nadine. "Impact de la fonctionnalisation enzymatique de la pectine par des composés phénoliques sur la structure et les propriétés physicochimiques du polymère". Thesis, Université de Lorraine, 2015. http://www.theses.fr/2015LORR0205/document.
This dissertation concerns the functionalization of the citrus pectin with phenolic compounds. A first strategy consisted in grafting the products issued from the oxidation of ferulic acid (FA), in aqueous medium (pH 7,5, 30 ° C), in the presence of the laccase of Myceliophthora thermophila (pectin F). The main objectives were to demonstrate the covalent grafting of exogenous phenols onto the polysaccharide, to collect information about the structure and the properties of the modified polymer and to compare them with the characteristics of the native one. A second strategy of functionalization was applied, based on the adsorption of FA oxidation products onto the pectin (pectin POX). Whatever the functionalization pathway, biochemical analyses showed the incorporation of phenolic compounds into the pectin. The structure and the properties of the modified pectins depended on the type of modification undergone by the polysaccharide (covalent grafting or adsorption). Structural analyses suggested that the covalent grafting of phenols involved the carboxyl groups of the pectin (ester bound) on which FA oligomers were bound. The properties of native and modified pectins (POX and F) were studied and compared aiming to highlight the changes brought by functionalization. The study of the thermal properties of pectin POX and F suggested less organized and less compact structures compared to the native one. The antioxidant activity of the modified pectins was improved whereas their hygroscopic character was decreased because of the incorporation of hydrophobic phenolic compounds. As the native pectin, the pectins POX and F presented a shear-thinning profile. However, the viscosity and the gelation rate measured for the pectin F were significantly decreased, compared with those obtained for the native pectin. The pectin POX presented an intermediate behavior. Preliminary results of assemblies demonstrated the possibility to associate the native or modified pectin to another polysaccharide, the chitosan, leading to microparticles capable to encapsulate an active ingredient such as the curcumin
Benbettaieb, Nasreddine. "Influence de traitements de réticulation sans solvant sur les propriétés de films à base de gélatine et chitosan encapsulant ou non des antioxydants naturels : caractérisations physico-chimiques et application". Thesis, Dijon, 2015. http://www.theses.fr/2015DIJOS045/document.
This thesis aims to develop an edible packaging made of a mixture of chitosan and gelatin (beef or fish), to better understand the influence of the electron beam irradiation and of the incorporation of natural antioxidants on the physico-chemical and functional properties of the films. A study of the effect of irradiation on antioxidants release kinetics in a simple liquid medium was studied for validation. A preliminary study first showed that the densification of the film-forming solution and the gel during drying does not depend on the thickness or concentration or time and suggests a Fickian diffusion of water in the matrix. The permeability to water vapor increases linearly with film thickness and especially when the extent of the relative humidity differential is high. This phenomenon is attributed to a swelling mechanism and plasticization of the gelatin-chitosan network by the water. The effect of the chitosan-gelatin ratio showed an improvement of the mechanical properties and barrier to water and oxygen of the films compared to chitosan films. These performance gains are due to the good miscibility of the two macromolecules and to the molecular interactions established after the formation of a polyelectrolyte complex, as confirmed by FTIR analysis. Irradiation of films after drying increases the polarity of the surface and the film hydrophilicity, and thus induces an increase in barrier properties to water vapor and oxygen, and also of the mechanical and thermal films. However, irradiation does not change the crystallinity of the films. The incorporation of antioxidants (ferulic acid, coumarin, quercetin and tyrosol) with or without irradiation acts differently on the organization of the macromolecular network and thus on the film properties. Thus, ferulic acid and tyrosol reduce the permeability of water vapor measured in a gradient of 0-30% relative humidity, while it increases up to 90 times with a gradient 30-84 % and an irradiation treatment. The oxygen permeability decreases significantly after addition of quercetin or tyrosol and after irradiation. Ferulic acid and coumarin increases the tensile strength of the films while they are quercetin and ferulic acid which allow to increase the thermal resistance of the films. These results thus demonstrate the complexity of the interactions involved between antioxidants and the chains of chitosan and/or gelatin, their dependence on the moisture level of the system and on the impact of cross-linking treatment by irradiation. It is noticed that the irradiation has protected the active molecules against oxidation for a long period of storage of the films. Release in aqueous medium of ferulic acid is the more delayed with the highest retention in the film at equilibrium (27%). The antioxidants diffusion coefficients, determined from the release kinetics, could be modulated (about 50%) by the irradiation treatments