Дисертації з теми "ChitosanNP"
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Martinez, Ruvalcaba Agustin. "Rhéologie des solutions de chitosane et des hydrogels de chitosane-xanthane Rheology of chitosan solutions and chitosan-xanthan hydrogels." Sherbrooke : Université de Sherbrooke, 2002.
Знайти повний текст джерелаMalaise, Sébastien. "Small Diameter Vascular Substitues Based on Physical Chitosan Hydrogels : Proof of Concept." Thesis, Lyon 1, 2014. http://www.theses.fr/2014LYO10057.
Повний текст джерелаChitosan presents biological properties (biocompatibility, bioresorbability, bioactivity) ideally suited for tissue engineering. In this partnership study (ANR TECSAN 2010 ChitoArt program), we worked at the elaboration of physical chitosan hydrogels presenting various and controlled physicochemical and biological properties, without any external crosslinkers. These hydrogels are envisioned under mono- or poly-membranous tubes for small diameter vascular substitutes (<6mm) purposes. Indeed, vascular engineering presents, even today, numerous limitations for small calibre vessels. Our strategy consists in the modulation of both structural (degree of acetylation, molar mass) and environmental (neutralization bath and collodion composition and concentration) parameters involved in hydrogels elaboration process in order to reach physical, biological and mechanical requirements suitable for this application. The study of hydrogels morphology by Cryo-Scanning Electron Microscopy (Cryo-SEM), using an original sample preparation method led to a better comprehension of chitosan hydrogels fine structure and multi-scale organization. This fundamental approach was conducted through the in vivo biological evaluation of hydrogels but also to mechanical characterizations of vascular substitutes. In particular, our substitutes were evaluated in term of suture retention resulting in the development of a formulation that led to suturable physical chitosan hydrogels, which were protected by a patent (Deposit number: FR1363099). Hydrogels elaboration parameters control and modulation have resulted in the development of colonisable vascular substitutes matching their in vivo implantation requirements (suture retention, compliance, burst pressure)
Coquery, Clément. "Fonctionnalisation du chitosane : vers un nouveau revêtement biosourcé pour la protection des métaux contre la corrosion." Thesis, Montpellier, Ecole nationale supérieure de chimie, 2018. http://www.theses.fr/2018ENCM0003/document.
Повний текст джерелаCorrosion treatment is an economic, environmental and health safety issue. More widely used on an industrial scale, coating protection consists in isolating the metal from the aggressive medium by an adherent, continuous and impermeable layer. They must have three major properties: 1) be strongly adherent to the metallic substrate, 2) have good barrier properties to limit the penetration of water and aggressive species and 3) provide a role in inhibiting corrosion. However, the protection of metal surfaces by current techniques generates significant pollution due to the use of chromates. The use of bio-based and soluble polymers in aqueous media would be a challenge and would contribute to preserving the environment. Polysaccharides such as chitosan are biodegradable and environmentally friendly macromolecules with anticorrosive properties and are therefore possible alternatives. These theses focus on the development of anticorrosion coatings based on chitosan. Chitosan has two weak points for use as a coating against corrosion: 1) insufficient adhesion on the surface of the materials and 2) hydrophilicity. As a result, chitosan has been chemically modified to increase its adhesion and barrier properties. In order to improve its adhesion on metal substrates, phosphonic acid groups have been added via the Kabachnik-Fields reaction on chitosan. The development of a chitosan with catechol functions was also discussed. Initially, the modified chitosan was tested and characterized by electrochemical impedance spectroscopy (EIS) as a corrosion inhibitor and coatings based on the same chitosan were made and their corrosion protection evaluated. Two approaches of coating elaborations were tested: dip-coating and Layer-by-Layer (LbL). Different ways of functionalizing chitosan have also been presented to increase the barrier properties of the coating. Phthaloylation chemistry of chitosan was described and hydrophobic chain grafting was studied
Malli, Sophia. "Formulations multifonctionnelles pour le traitement des infections parasitaires cutanéo-muqueuses." Thesis, Université Paris-Saclay (ComUE), 2019. http://www.theses.fr/2019SACLS043.
Повний текст джерелаThis project aims at developing new therapeutic strategies against parasitic muco-cutaneous infections such as urogenital trichomonosis and cutaneous leishmaniasis which still represents a major health problem worldwide.Unfortunately, metronidazole (MTZ) is a first-line systemic treatment for urogenital trichomoniasis that causes resistance and side effects. We have thus developed new strategies by acting on both the pharmacological and the physical mechanisms of Trichomonas vaginalis infection. After a successfull increase of the apparent solubility of MTZ in water using a methylated -cyclodextrin, we formulated it in a thermosensitive and mucoadhesive hydrogel composed of pluronic® F127 and a cationic and mucoadhesive biopolymer, chitosan. This formulation is specifically adapted for topical application providing a control of MTZ release and reduction of its systemic passage through the vaginal mucosa.Then, the ability of the high viscosity hydrogel to immobilize T. vaginalis was investigated by video-microscopy. Monitoring the trajectories of each parasite by multiple particle tracking showed the ability of the hydrogel alone or in combination with chitosan to completely immobilize T. vaginalis and to inhibit parasite attachment to the mucosa. These evaluations were performed on mice experimental model. However, chitosan alone did not allow parasite immobilization and did not show any anti-T. vaginalis activity. In this context, we were inspired by previous works conducted by our team on the development of formulations based on chitosan, and more particularly nanoparticles (NPs) composed of poly(isobutylcyanoacrylates) coated with chitosan. These NPs have their own trichomonacidal activity, even without adding active substances, while NPs without chitosan were inactive. Investigated of the mechanism of the activity showed better internalization of NPs when coated with chitosan. These NPs caused drastic morphological alterations on the parasite membrane. This activity could be due to the electrostatic interaction between negatively charged T. vaginalis surface and cationic chitosan coated NPs.In order to broaden the applications of these NPs to other parasites, we were interested in evaluating the anti-L. major activity of NPs coated or not with chitosan. Indeed, chitosan known for its healing properties could be particularly adapted for this pathology. We thus showed in vitro and in vivo that NPs coated with chitosan had intrinsic anti-L. major activity without adding any drug. In a second step, we decided to design chitosan elongated particles and to evaluate their anti-leishmanial activity. These particles called "platelets" are composed of chitosan hydrophobically-modified with oleic acid and cyclodextrin in water. This strategy could be interesting to improve the interaction of platelets with the L. major membrane, as these parasites had also non-spherical morphology. The histological and immunohistochemical results of skin lesions showed a significant decrease in inflammatory granuloma and a reduction in parasitic load compared with amphotericin B alone, used as a reference.In conclusion, during this thesis, several formulations were developed and showed biological activities by acting on pharmacological and/or physical mechanisms of the parasites
Loron, Anne. "Chitosan polymers and plant extracts to develop biofungicides." Thesis, Bordeaux, 2021. http://www.theses.fr/2021BORD0002.
Повний текст джерелаCereals are subject to contamination by pathogenic fungi, which damage grains and threaten the public health with their mycotoxins. Recently, the raise of public and political awareness concerning environmental issues tend to limit the use of traditional fungicides against these pathogens in favour of eco-friendlier alternatives. In this framework, this thesis work aims to create a formulation based on renewable products in order to limit the fungal development and control the production of mycotoxins from cereal fungi. Our work exploits the remarkable properties of three compounds: the chitosan, a chitin derived biopolymer, the tetrahydrocurcumin (THC), a curcumin derivative, and plant extracts. In a first step, we studied and characterise the physicochemical properties of different chitosans. Chitosan solutions were shown to reduce the mycelial growth of a target model fungi Fusarium graminearum, and to divide by 2 the accumulation of mycotoxins. In addition, we showed that this biopolymer was able to maintain its antifungal properties as a form of a coating. In a second step, we focused on different plant extracts with antimicrobial activities. THC was able to inhibit the toxin production and a maritime pine by-product showed its potential to control the fungal growth. The combination of the THC or the wood extract with chitosan was then studied to increase the efficiency of the formulation. To this end, a significant work was made to increase the solubility of THC in water by forming an inclusion complex in cyclodextrins or by protecting it in starch or chitosan particles. In particular, we showed that the addition of pine extracts to a chitosan-based solution can double the effectiveness of the formulation
Rami, Lila. "Qualification d’hydrogels physiques de chitosane et de progéniteurs endothéliaux humains pour l’ingénierie vasculaire." Thesis, Bordeaux 2, 2013. http://www.theses.fr/2013BOR22047.
Повний текст джерелаAbstract
Enache, Alexandru Alin. "Mathematical modelling of the chitosan fiber formation by wet-spinning." Thesis, Lyon, 2018. http://www.theses.fr/2018LYSE1100/document.
Повний текст джерелаChitosan is a natural polymer obtained by deacetylation of chitin. This polysaccharide is well known for its exceptional biological properties: it is biocompatible and bio absorbable. Chitosan fibers can be used in surgery.The objective of this thesis is to study the physicochemical phenomena involved, to develop a process model, to optimize the filtering process in the laboratory.After a review of the literature in the first chapter, the experimental techniques for obtaining, purifying and characterizing chitosan are described in the second chapter. A study of the structure of the chitosan obtained is presented. This is one of the original results of this work.The principle of the coagulation method in solution, it is essential to determine in what condition it, and what is the determining parameter. Previous studies have shown that this is the diffusion coefficient of soda in the medium. One effect, measurements were made, in different geometries. This study constitutes the work presented in Chapter Three.In chapter four is presented a technique consisting in following by means of a microscope the advance of the coagulation front. This technique makes it possible to determine the diffusion coefficient.The last chapter consisted of developing fibers using a small scale plant existing in laboratory (IMP Lyon 1). The final element of this work consists of modelling the process, calculating the inside and outside diameters of the fibers obtained and comparing the result of the modelling with the experimental results
Lalevée, Gautier. "Complexes polyélectrolytes d'acide hyaluronique et de chitosane pour des applications biomédicales." Thesis, Lyon, 2017. http://www.theses.fr/2017LYSE1075.
Повний текст джерелаThis work is devoted to the elaboration of polyelectrolyte complexes systems combining two oppositely-charged polyelectrolytes and to the study of their potential application as - injectable dermal fillers. Hyaluronic acid as polyanion (carboxylic groups -COO as negative charges) was complexed with the only naturally-occuring polycation named + chitosan (amine groups -NH3 as positive charges). The factors impacting the formation of hyaluronic acid - chitosan complexes and their physico-chemical properties were investigated. We used a new technique of complexation developed in the laboratory through the desalting of highly salted mixtures, and systematically investigated the impact of pH in the range 2.5 - 6.5, corresponding to the complexation domain of hyaluronic acid and chitosan. This process allowed the progressive elimination of the salts and the slow restoration of the attractive electrostatic interactions resp onsible for the self-assembly of the two polyelectrolytes. Various physical forms were obtained: macroscopic aggregates, soluble complexes, colloidal suspensions or hydrogels. During this work, we observed for the first time the formation of hyaluronic acid-chitosan hydrogels exhibiting a very unusual hyper-stretchability, only at acidic pH. Therefore, an alternate approach consisted in taking advantage of the chitosan ability to gel in alkaline medium. By using a similar process, we were then able to form physically-crosslinked hyaluronic acid-chitosan hydrogels stable at physiological pH and osmolarity and still able to undergo high deformations. Moreover, these systems could be submitted to steam sterilization and could be formulated so as to be injectable. Hence, these hydrogels gathered all the conditions to be good candidates as injectable biomaterials, these hydrogels were then tested in vivo on a rabbit model to evaluate their biocompatibility and suitability for intradermal applications
Mati-Baouche, Narimane. "Conception d'isolants thermiques à base de broyats de tiges de tournesol et de liants polysaccharidiques." Thesis, Clermont-Ferrand 2, 2015. http://www.theses.fr/2015CLF22548/document.
Повний текст джерелаOne of the issues relating to the sustainability of thermal insulation in the building industry is the use of composites derived from agricultural resources. These composites are typically agglomerated with mineral binders or from synthesis. To explore the use of polysaccharide binders for the conception of insulation panels based one sunflower stem aggregates (reinforcement), chitosan has been chosen as polysaccharide model. After a first stage of physico-chemical, thermal and mechanical characterizations of the binder and the reinforcement, an experimental design was established to find the best values of the particle size, the ratio binder/reinforcement and the compaction stress affecting the thermo-mechanical properties of the composites. A composite with a thermal insulation of about 0.06 W.m-1.K-1 and a maximum strength (in tension and compression modes) of 2 MPa was obtained with a ratio chitosan/sunflower stalk aggregates of 4.3 % and a size of 6.3 mm for the aggregates. The mechanical and thermal performances are superior to that of other biobased insulators available on the market. Formulation of the binder by covalent crosslinking (genipin) and by the addition of other biopolymers (alginate, guar gum, starch) with binding property has been achieved through the development of a fractional factorial experimental design. The results show the ability to maintain satisfactory mechanical and thermal properties with reducing chitosan content
He, Jing. "Des (bio)nano-composites utilisés dans le traitement d'eaux contaminées par de l'arsenic/gentamicine ou pour des applications médicales." Phd thesis, Université de Grenoble, 2013. http://tel.archives-ouvertes.fr/tel-00988092.
Повний текст джерелаGiacalone, Giovanna. "Implant chargé en nanoparticules pour la libération contrôlée et le ciblage lymphatique de nucléotides et d’analogues nucléotidiques." Thesis, Paris 11, 2014. http://www.theses.fr/2014PA114845.
Повний текст джерелаNatural nucleotides and nucleotide analogs display important pharmacological activities: for example the nucleotide adenosine triphosphate (ATP) could be an interesting molecule for the treatment of ischemia or atherosclerotic plaques. The clinical use of these molecules is however limited due to the presence of a triphosphate group, which is prone to hydrolysis in vivo, and responsible for the high hydrophilicity of the molecules, thereby strongly limiting their uptake by targeted cells and access to their intracellular pharmacological targets. To overcome these limitations and enable the administration of nucleotides and nucleotide analogs, the use of drug delivery systems such as nanoparticles may enable the protection and the targeted delivery of these drugs. Nanoparticles designed for intravenous injections are however not always convenient, e.g. in the case of chronic diseases. Therefore, a subcutaneous implant with sustained release features might represent a valid alternative, which is less invasive and can reach lymphatic tissues (important targets of many therapies). The first chapter of this thesis presents the formulation of nanoparticles to encapsulate ATP as well as zidovudine triphosphate (AZT-TP), thanks to the presence of chitosan (CS). These nanoparticles are formed through ionic interactions between the positive charges of chitosan and the negative charges of the triphosphate groups of ATP or AZT-TP. In this work, nanoparticles are characterized and their cellular delivery of ATP and AZT-TP inside a macrophage cell line is demonstrated. In a second time, the stability of these systems has been improved in order to obtain a better behavior in physiological conditions. This improved stability has been achieved through the complexation of chitosan to iron(III) (CS-Fe). This strategy has been applied to TPP and ATP nanoparticles. These nanoparticles have been tested on two macrophages cell lines showing an improved internalization compared to the previous ones. Finally, CS-Fe/ATP nanoparticles have been dispersed in a PLGA solution in order to develop an in situ forming implant. Once in contact with physiological fluids, the suspension turns into a solid depot. In vitro release studies show the ability of the systems to retain nanoparticles inside the matrix and to gradually release them over 5 days. After subcutaneous administration to mice, PLGA implants containing nanoparticles were able to retain ATP at the injection site for up to 50 hours, as compared to few hours of free ATP or free nanoparticles, showing therefore their relevance as sustained release systems of nucleotides
Le, Grill Sylvain. "Composite chitosane-phosphate de calcium : synthèse par atomisation séchage et caractérisation structurale." Thesis, Toulouse 3, 2018. http://www.theses.fr/2018TOU30023/document.
Повний текст джерелаThis thesis deals with the development and characterization of a chitosan/calcium phosphate composite material for use in the field of bone substitution. The spray-drying method was chosen to develop this composite in the form of a powder that could be transformed into a coating or 3D object. A preliminary study made it possible to understand the mechanisms of synthesis of calcium phosphate, the mineral phase, by spray-drying. A suspension of stoichiometric hydroxyapatite particles or biomimetic apatite dispersed in an acidic solution systematically leads to the appearance of an amorphous phase. The proportion of this amorphous phase in the spray-dried powder is dependent on the size and crystallinity of the original material. The spray drying of an acidic solution containing the precursor ions of calcium and phosphate leads to the formation of a mainly amorphous phase. This powder could be described at different scales: on a scale of about one nanometer appear clusters, on a scale of about one hundred nanometers spherical aggregates of clusters organized into tortuous and nested chaplets are identified and finally on a micrometric scale, agglomerates of nanoparticles were highlighted. The calcium phosphate thus synthesized has a molar ratio Ca/P close to 1.3. Beyond this ratio in the solution to be atomized, calcium acetate (used here as a precursor) recrystallizes in the powder. To develop the composite powder, the polymer was solubilized and added first into an acid suspension of hydroxyapatite before atomization. This first strategy leads to the formation of a composite that has strong in homogeneities in the distribution of organic and inorganic phases. To limit this problem related to the grain size distribution of the mineral phase, a second strategy has been developed. A polymer solution containing calcium phosphate precursors has been prepared to promote nanoscale association of the two phases. After spray-drying, a composite material having a very good dispersion of the mineral phase in the organic matrix is synthesized. The structuring of the mineral phase is modified by the presence of the polymer. This modification results in a reduction of the volume fraction of the clusters and, on the larger scale, the mineral phase is no longer present in the form of a string but in isolated spherical particles. Moreover, a chemical interaction is envisaged because of the hydrogen, ionic or possible coordination bonds between the two phases. The presence of the polymer also inhibits the formation of crystalline calcium acetate by promoting the formation of a salt of chitosan acetate. Two shaping techniques were studied (MAPLE, for the elaboration of thin coatings and the 3D printing of dough for obtaining massive objects) and made it possible to highlight the transformation potential of the prepared powder by spray drying. The biological studies made on the coating have also demonstrated the antibacterial properties of the material used
Castel, Marion. "Mise en forme et caractérisation de biomatériaux pour la prévention des fistules pancréatiques après pancréatectomies." Thesis, Toulouse 3, 2017. http://www.theses.fr/2017TOU30193.
Повний текст джерелаResection surgery is the first-line treatment indicated for pancreatic tumor. The morbidity of this surgery is high with a complication rate around 50%. One of the most serious complications is the occurrence of pancreatic fistula (PF), which occurs in 15-20% of cases. To date, no biomaterial available on the market is indicated for the prevention of the onset of PF following pancreatectomy. This project focuses on the development of a biomaterial for the prevention of PF. Specifications identified by the surgical team oriented us to ward an absorbent dressing with sufficient mechanical properties and pancreatic enzymes resistance. A biomaterial made up of two layers was designed: 1) an absorbent matrix, in the form of a film, constituted by a polyelectrolyte complex (PEC), 2) an impermeable backing layer expected to limit the diffusion of the pancreatic enzymes into the peritoneal medium; to meet surgeons' specifications. The first part of this work focused on the optimization of the preparation of the matrix, composed of alginate (ALG) and chitosan (CHI) PECs films with different polymer ratios (ALG-CHI 50/50and ALG-CHI 63/37). The influence of the technique of homogenization of PEC, ultra-turrax (UT) or Stephan (ST) was studied on the physicochemical properties of the films. Biodegradation, swelling and cytotoxicity were shown to be mainly influenced by the ratio of polymers used. On the other hand, structure and mechanical properties are mainly influenced by the homogenization technique. With these results, the choice of the matrix to pancreatic application was set as the PEC ALG-CHI 63/37 UT. The second part of the present work was devoted to the incorporation of an impermeable backing layer on the upper film surface. Two polymers were evaluated: polylactic acid (PLA) and polycaprolactone (PCL). They were incorporated after the functionalization of the film surface. The PLA-coated ALG-CHI 63/37 UT matrix led to more hydrophobic surfaces, as well as adaptated mechanical properties and resistance to pancreatic enzymes with interesting swelling properties. The obtained biomaterial is a promising candidate responding to the specifications for a dressing indicated for the prevention of PF
Cisse, Mohamed. "Immobilisation d’un système lactoperoxydase dans un enrobage de chitosane dans le but de prolonger la conservation des mangues." Thesis, Montpellier, SupAgro, 2012. http://www.theses.fr/2012NSAM0012/document.
Повний текст джерелаThe mango export is limited by the rapid ripening and microbial growth on the fruit. This thesis proposes a new approach to safe and healthy using natural molecules to improve post-harvest conservation of mango and thus help preserve the health of consumers and improved the potential of international trade in certain exporting countries. This work shown that the immobilization of the lactoperoxidase in the chitosan film and applied as coating of mangoes could maintain the microbiological and physicochemical quality of fruits. Chitosan-coupling lactoperoxidase system extended the shelf life of mangoes for over two weeks without affecting their organoleptic quality.This work also helped to highlight the synergy between the lactoperoxidase and the concentration of chitosan. An optimum coating made from 1% chitosan allowed to fix the enzyme system and to maintain the mangoes in a good sanitary condition. The presence of iodine in the lactoperoxidase does not act significantly on the conservation of mangoes
Dumont, Mélanie. "Élaboration et caractérisation de fibres mixtes Alginate / Chitosane." Thesis, Lyon, 2016. http://www.theses.fr/2016LYSE1303/document.
Повний текст джерелаIn this work, the preparation of chitosan-coated alginate fibers by a wet spin process and the characterization of these fibers, particularly their antibacterial activities are presented. A pilot scale spinning machine was developed during this thesis for the elaboration of calcium alginate fibers. These last, preformed produced were immersed in chitosan acetate solutions. Three coagulation methods of the chitosan coating were explored two of which consist to the immersion of the fibers in a neutralizing bath: a calcium hydroxide solution or a potassium hydroxide solution. The last method is to neutralize chitosan by drying under hot air blown. Structural, mechanical and absorption characterization of fibers and a dose of the coated chitosan have been made. Furthermore, the antibacterial evaluation was achieved by a CFU (Colony-Forming Units) counting method after 6 h of incubation at 37 °C. The incorporation of chitosan on calcium alginate fibers brings antibacterial activities against Staphylococcus epidermidis, Escherichia coli and various Staphylococcus aureus strains namely MSSA (Methicillin Sensitive Staphylococcus aureus), CA-MRSA (Community Associated Methicillin Resistant Staphylococcus aureus) and HA-MRSA (Healthcare Associated Methicillin Resistant Staphylococcus aureus) which make these chitosan-coated fibers potential candidates for wound dressing materials. Developing a wound dressing with the haemostatic and healing properties of alginate combined with antibacterial properties of chitosan can be envisioned for fighting against the infections and more particularly nosocomial infections
Pibre-Weber, Caroline. "Caractérisation et comparaison des propriétés immunostimulantes de nanoparticules biodégradables de poly(acide lactique) et de chitosane après adsorption de TLR ligands ou d’antigènes du VIH1." Thesis, Lyon 1, 2010. http://www.theses.fr/2010LYO10333/document.
Повний текст джерелаUse of nanoparticulate vectors in vaccination as controlled release systems based on biodegradable polymers has been widely studied, particularly for HIV vaccine research. An innovative approach is to co-administer antigens of interest with immuno-stimulatory molecules to amplify the recruitment and activation of dendritic cells (DCs). Such a vaccine candidate could boost the intensity of the immune response, and mucosal immunity in vaginal and anal secretions could be obtained after vaccination.We used nanoparticles of poly(lactic acid) (NP-PLA) or chitosan / dextran sulfate (NP-CSD), as vehicles and adjuvants for HIV-1 proteins, gp140 and p24. Poly (I:C), TLR3 ligand molecule, is the immuno-stimulatory molecule chosen for its adjuvant properties. The NP-PLA and NP-CSD have shown their great potential as carriers of proteins. By cons, if NP-CSD allows the adsorption of poly(I:C) with a yield of 95%, the adsorption is less reproducible on NP-PLA. For each formulation, the ability to induce in vitro maturation of DCs was evaluated by following the marker CD25, CD80, CD83, by flow cytometry. Adsorption of poly(I:C) on the NP-PLA or the NP-CSD amplifies the maturation abilities of particles and has a synergistic effect with the NP-CSD.Our work shows that co-adsorption of a TLR ligand with HIV protein antigens onto biodegradable nanoparticles is possible and gives an immuno-stimulant effect to the vaccine formulation in vitro. In vivo, vaccine formulations containing poly(I:C) induce very high levels of serum antibodies in mice
Roux, Rémi. "Élaboration d'assemblages colloïdaux à partir de nanoparticules de poly(acide lactique) et de chitosane." Thesis, Lyon 1, 2013. http://www.theses.fr/2013LYO10088/document.
Повний текст джерелаColloidal assemblies may be a promising pathway to obtain injectable scaffolds favoring the development of neo-tissue in regenerative medicine. This work investigates the formation of such assemblies composed of chitosan, soluble or in suspension (nano-hydrogel), and poly(lactic acid) (PLA) nanoparticles. Two types of assemblies are studied. As a first approach, mixing negatively charged PLA particles and chitosan solution leads to the formation of “composite gels”, based on colloidpolymer interactions. Rheological and Small Angle X-Ray Scattering measurements highlighted the formation process and the influence of various parameters on final properties of these gels, which features shear-thinning and reversibility behavior, that is, the capacity to gel again after yielding. PLA nanoparticles could also be mixed with cationic chitosan nanoparticles, which are crosslinker free nano-hydrogels, leading to the formation of “colloidal gels”, based on colloid-colloid interactions. Influence of various parameters on gel synthesis and properties are investigated through rheological measurements. The study also focuses on the characterization and control of the morphological and cohesion properties of chitosan nanogel
Blanchard, Kévin. "Développement de nouveaux systèmes de délivrance de vaccins à base de polysaccharides." Thesis, Lyon, 2016. http://www.theses.fr/2016LYSE1184.
Повний текст джерелаVaccination, especially in animal species, remains already an efficient tool in the prevention of infectious diseases. The carrier and immunostimulant properties of adjuvant allow increasing the action of antigen which, alone, is not enough capable to induce a long and strong immune response in host. The unique properties of chitosan, a biocompatible and biodegradable natural polymer, offer a choice material to elaborate new generations of adjuvant such as nanoparticles or hydrogels.This PhD works was focus on the development of chitosan-based adjuvant for animal species. The preparation of chitosan-based viscous solutions, with a polymer concentration from 0.2 to 0.75 % (w/v) mixed with different kind of antigens such as live attenuated bacteria, live attenuated or inactivated virus and a recombinant protein allowed obtaining an immune response in the studied animals. Moreover, the observation of animals during the protocol or in post-mortem inspections indicated a satisfying safety and resorbability. In vitro experiments were also conducted developing a syringeable and injectable in situ gelling chitosan-based hydrogel containing a model protein, destined to standard injection system. The slow release of antigen in the host should interact with the immune system longer increasing the final protection against diseases
Aubert-Viard, François. "Conception et évaluation d'un pansement multicouche antibactérien pour le traitement des plaies chroniques." Thesis, Lille 2, 2014. http://www.theses.fr/2014LIL2S027/document.
Повний текст джерелаThe chronic wounds represent a public health problem health which the prevalence increases with age, patient health and sedentary lifestyle. Indeed, in the occidental countries, 1.69% of the elderly person aged over 65 years is suffering from leg ulcers . Moreover, the chronic wounds appearance increases for the diabetic patients who suffering neuropathy (diabetic type I and II together) with 2.2%/years of probability to developp a leg ulcer. The infection of the chronic wounds increases with wound healing delay, thus, cares need to be repeated to prevent or fight wound infection until their complete healing. In the case of infected wound, the critical colonization or localized infection can result without adapted treatment to surgery operation in order to prevent systemic infection or death. Nevertheless, the chronic wound represents a favourable site for the rapid developpment of the pathogen agents. The bacterial proliferation can lead to the biofilm formation which increases the bacterial protection against the body\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\'s natural defences and antimicrobial agents. So, the aim of this work is elaborate a medical device as wound dressing for extended broad spectrum antibacterial drug release. The textile device used in this project is a non-woven textile based on polyethylene terephtalate (PET) functionalized with Pad-Dry-Cure method with chitosan (CHT). In the present work, two crosslinking agents are evaluated, genipin (Gpn) and citric acid (CTR), which allows obtaining a CHT network coated at the surface of the textile fibers. Thus, there are ionic functions at the surface of the PET; positive charges when the crosslink agent is Gpn, positive or negative charges in function of the amount of the CTR used in the solution.The ionic charges from the PET functionalized by CHT crosslinked by Gpn (PET-Gpn/CHT), are used to build a multilayer system layer-by layer self-assembly. The polyelectrolytes (PE) used to build this multilayer system by dip-coating are: the CHT, as cationic PE, and cyclodextrin (CD) polymer, as anionic PE (it was developed and studied by the team in previously work). The ability of the CD to form inclusion complex, from the CD polymer included in the multilayer coating, is used in the case of PET-Gpn/CHT to load one antiseptic with broad spectrum, the chlorhexidine (Chx). This Chx loaded multilayer system is optimized and evaluated physic-chemically, biologically and microbiologically. The study is also realized on the functionalized PET-CTR/CHT. This system, anionic or cationic, in function of the quantity of the crosslinking agent used, is loaded respectively by silver (Ag+) or iodide (I3-). A physico-chemical and microbiological evaluation are realized to evaluate their antibacterial efficiency. Finally, the multilayer system is built-up on the anionic PET-CTR/CHT loaded by silver to reduce its release out of the multilayer system. Chemical completed by microbiology tests are realized to verify the influence on the antibacterial activity and the kinetic of the release of the multilayer system
Garcia, Garcia Christian Enrique. "Electrofilage de systèmes polymères à base de chitosane pour la production de substrats nanostructurés. Caractérisation et application potentielle en ingénierie tissulaire." Thesis, Université Grenoble Alpes, 2022. https://tel.archives-ouvertes.fr/tel-03789645.
Повний текст джерелаTissue engineering represents a potential approach to improve cartilage mending, where an artificial 3D extracellular matrix (ECM) is essential to generate new tissues. Native ECMs can be effectively mimicked by electrospun nanofiber membranes, specially using natural sourced polymers.In this work, chitosan (CS)-based systems (CS and CS/Hyaluronan (HA)) are transformed, by electrospinning, into biocompatible and biodegradable nanofibrous mats adapted for chondrocyte (CHCT) development. CS materials are claimed to favor cell adhesion and growth, providing the microenvironment adequate for CHCT phenotype preservation. No current procedures for cartilage renovation have successfully achieved long-lasting cartilage regeneration.Homogeneous CS, HA, and CS/HA polyelectrolyte complex solutions are prepared using formic acid mixtures as solvent. Stability of the complex is improved by thermal treatment at 120°C. After treatment, material crystallization and amide bond formation are related to modifications of physicochemical properties.Enabling electrospinning, polyethylene oxide (PEO) is incorporated to the CS and HA solutions. The PEO content in the blend is set at 30 % and electrospun CS/PEO and CS/HA/PEO fibers are obtained, with diameters ranging between 100-200 nm. Several collector types allow the production of nanofibrous mats with a visible fiber arrangement depending on the collector structure. Patterned fiber mats are produced and applied for CHCT culture and cell morphology observation.Atomic force microscopy measurements between single CHCT and CS film and fibers, help to compare adhesion strength as a function of substrate topography. The cell-substrate adhesive force is found slightly higher in the case of CS film compared to the mat. Nevertheless, adhesion is more efficient on the mats, considering a lower effective contact area (support porosity ~40%).For cell culture, the importance of CS fiber stabilization is highlighted. Cell proliferation tests, performed on CS fiber mats, revealed that fiber mats lead to higher proliferation rates compared to casted films.Topography of electrospun CS nanofiber membranes could impact cell colonization patterns. Cell alignment in certain zones of aligned fiber samples is detected. In the same way, concentration of cells is observed on zones of the mat more fiber densely charged.When comparing CHCT development on CS and CS/HA substrates, it is found that cell confluency is achieved earlier on CS/HA than on CS fibers. Cell development could be improved by the presence of HA in the support, as a natural component of the ECM, favoring cell adhesion. In both cases, high CHCT viability (>90%) is detected.Regarding cell morphology, primary CHCT maintain an oval shape in cartilage. This form is also observed for CHCT on CS and CS/HA fibrous mats. On the contrary, cells spread during monolayer cultures on flat surfaces such as films and Petri dish. Morphology preservation could indicate native cell characteristics maintaining.As an alternative for cell/substrate implantation, the feasibility of intra-articular injections of cell/fiber suspensions is studied. Proliferation profiles differ significatively from CS fiber mats, mainly attributed to the limited available surface for cell development on the fiber suspension in contrast with the continuous mat. However, since some patients do not fit for surgery, the injectable approach could become a viable treatment for cartilage regeneration.In conclusion, electrospinning process optimization and material characterization allowed the use of stable nanofiber mats for CHCT development in pursuit of tissue repair applications. Compatibility of CS-based fiber mats is confirmed and substrate efficiency compared as a function of material topography.Considering the promising results herein obtained, CS and CS/HA nanofibrous mats can be considered as potential scaffolds maintaining adequate proliferation profiles and native cell shape
Nakamatsu, Javier. "Chitosan." Revista de Química, 2013. http://repositorio.pucp.edu.pe/index/handle/123456789/100553.
Повний текст джерелаChitin is an abundant biopolymer that can be found in shells of crustaceans, insects and in squid and pota pen. Deacetylation of chitin produces chitosan, a more versatile polysaccharide due to its solubility and increased chemical reactivity. Chitosan is used in medicine, pharmaceutics, cosmetics, water treatment, agriculture and food industry.
Roux-Pertus, Charles. "Investigation de la Pulvérisation Électrohydrodynamique du Chitosan." Electronic Thesis or Diss., Université de Lorraine, 2019. http://www.theses.fr/2019LORR0335.
Повний текст джерелаElectrohydrodynamic (EHD) methods enable to produce with one low cost set-up polymeric films/particles by electrospray or polymeric fibres by electrospinning. Particles or fibres produced by these methods can be very uniform in size. Therefore, electrospray and electrospinning of chitosan are appealing topics of re-search. Chitosan is a bio-based material possessing numerous qualities such as biocompati-bility, biodegradability, antibacterial activity and muco-adhesion. This thesis deals with EHD methods with a focus on chitosan electrospray whose applications are abundant in health (tissue engineering, drug delivery), food (nutrients en-capsulation, cling film), wastewater treatment and textiles. However electrospray has several limitations. First, effective electrospray depends of the grade of the chitosan, of the preparation of the solution and of used set-up. Second, particle-size distribution reported in literature are broad whereas applications such as drug delivery require monodisperse particle-size distributions. Then, the question is to know how to produce chitosan particles of monodisperse controlled size. To answer this question, a critical analysis of literature led to an experimental approach divided in four steps : (1) characterization of chitosan, (2) measurement of chitosan solution properties, (3) study of stability of electrospray process, (4) assessment of deposit morphology and particle-size distribution. Finally, as part of a biomimetic approach, imitation with chitosan of natural shapes has been studied. These shapes are part of structures that confer striking properties such as hygrochromic behavior and hydrophobicity to insects
Quaillet, Marion. "Nanoformulation d'une molécule antirétrovirale pour le ciblage des réservoirs du VIH-1." Thesis, Université Paris-Saclay (ComUE), 2018. http://www.theses.fr/2018SACLS472.
Повний текст джерелаAlthough highly active antiretroviral therapies (HAART) have significantly improved the HIV infection treatment, important hurdles remain towards an HIV cure. Due to their low bioavailability, penetration and/or residence time, antiretrovirals have restricted access to tissue compartments such as lymphoid tissue and latent HIV reservoirs. Reservoirs prevent the eradication of the virus and result in a lifelong treatment for HIV infected patients. Currently, compliance and the patient quality of life are limited by dose frequency.During this thesis, chitosan-based nanogels are developed and evaluated for the enfuvirtide delivery, an HIV-1 fusion inhibitor peptide. The cellular distribution of enfuvirtide delivered as nanogels show the combined effect of physicochemical properties in terms of particle size and surface charge. Nanogels also maintain the antiviral activity of enfuvirtide on HIV-infected cells. In vivo studies, after subcutaneous administration in mice, demonstrate the ability of nanogels to target lymph nodes. Furthermore, nanogels were incorporated in an in situ forming implant. After subcutaneous injection, the implant allows gradual release of nanogels over several days
Mahé, Olivier. "Synthèse organocatalytique de δ2-pyrazolines par addition d’aza-michael et développement d’organocatalyseurs hétérogènes à base de chitosane". Thesis, Rouen, INSA, 2011. http://www.theses.fr/2011ISAM0018.
Повний текст джерелаAn organocatalytic racemic synthesis of 3,5-diaryl pyrazolines was developed, using guanidine as catalyst. Then, an enantioselective synthesis of N-Boc 3,5 diarylpyrazolines under phase transfer catalysis, achieving high enantiomeric excesses up to 94 %. Transprotection reactions of the Boc moiety allowed the introduction of a variety of functional groups on N1 atom of the pyrazolines ring. Finally, we applied this strategy to the synthesis of biologically active pyrazoline. Secondly, we used the chiral biopolymer chitosan in aminocatalysis, as a heterogeneous organocatalyst. We performed chemical modifications either by grafting proline, or by a benzyl moiety leading to secondary polyamines. The obtained materials were tested in different organocatalytic reactions. A 80 % enantiomeric excess has been reached for an aldolisation reaction. Finally, we applied, for the first time, the ionic liquid supported phase strategy on chitossan for aour organocatalysed reactions
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.
Повний текст джерелаThis 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
Altounian, Anais. "Élaboration et application d’agents fixateurs de colorants à base de chitosane pour l’industrie papetière." Thesis, Lyon, 2018. http://www.theses.fr/2018LYSE1348.
Повний текст джерелаOver the past years, progresses have been achieved in the field of the paper industry. Moreover, the development of biosourced materials has been studied under intense investigations.The elaboration of chitosan-based fixing agents of anionic food dyes intended to paper industry is in line with this R & D context. This project, proposed by the company Colorey and carried out in collaboration with IMP laboratory (UMR 5223), consisted in using chitosan (the only natural polycation) as such for the surface dyeing of paper or, modified with the glycidyltrimethylammonium chloride (GTMAC) as quaternized chitosan (Chi-GTMAC), for the mass dyeing of the pulp. This last process required a neutral or slightly alkaline pH within the pulper, which cannot allow the solubilization of chitosan. Hence, chitosan was derivatized into Chi-GTMAC, bearing trimethylammonium moieties as pH-independent functional groups. The thermal stabilities and the aqueous solubilities as a function of pH of these derivatives were investigated in order to determine whether they could support the drying temperature of the papermaking process or whether they could be used within the pulper for mass coloration. Then, the efficiency of some of the obtained derivatives to color the pulp and to fix dyes was determined thanks to a designed of experiments. Chitosan, for its part, has been tested as fixing agent for surface coloration of paper
Vo, Nguyen Dang Khoa. "Synthèse et propriétés de nanoparticules d’or par chimie sous rayonnement utilisant des polysaccharides naturels comme agents stabilisants." Thesis, Reims, 2013. http://www.theses.fr/2013REIMS021/document.
Повний текст джерелаThe goal of this work is to develop a methodology for the synthesis of gold nanoparticles in the presence of chitosan under radiation to obtain a homogeneous object and controlled size. To reach this purpose, we will focus on the study of interactions between the ions Au(III) and chitosan in solution before irradiation. Indeed, the coordination between units of glucosamine and Au(III) promotes the reduction of Au(III) to Au(0) and the formation of gold nanoparticles. This is clearly demonstrated by the influence of pH on the formation of nanoparticles upon aging of HAuCl4 solutions in the presence of chitosan. This formulation has been used to explain the mechanism of reduction of Au(III) in the presence of chitosan in radiation. It was to define whether the reduction mechanism of ion Au(III) ions Au(0) followed a conventional process such as those described by the work of Belloni and Henglein, or if the presence of chitosan affects this process. The development of gold nanoparticles in the presence of chitosan used as a stabilizing agent was produced by the electron beam and gamma radiation. The influence of the synthesis parameters (report [GLA]/[Au (III)], sample conditioning, effect of irradiation dose, dose rate effect, role of a radical scavenger) on the characteristic gold nanoparticles was then evaluated (size, charge, surface plasmon resonance). The catalytic activity of these nanoparticles was tested towards the reduction reaction of 4-nitrophenol to 4-aminophenol by NaBH4.Keywords: gold, nanoparticles, chitosan, coordination, irradiation, electron beam, gamma radiation, 4-nitrophenol
Conzatti, Guillaume. "Biomatériaux pour application chirurgicale : élaboration et fonctionnalisation pour une bioadhésion thermorégulée." Thesis, Toulouse 3, 2017. http://www.theses.fr/2017TOU30159/document.
Повний текст джерелаPancreatic surgery, which leads to 5 % of mortality and around 50 % of morbidity, is one of the most critical digestive operations. The most serious complication is the appearance of pancreatic fistulas (PFs), i.e. enzymatic leaks from the surgical sutures to the peritoneal environment that can lead to the life threatening of the patient. To date, no medical device is indicated for the prevention of these FPs. The aim of this project is to design and validate a biomaterial constituted of a matrix that will ensure the dual function of absorbent and antibacterial agent reservoir, on which a chemical grafting should confer thermoregulated bioadhesive properties. The first part of this work is devoted to the optimisation of the absorbent matrix, based on alginate and chitosan, already developed during a previous thesis. Three types of drying processes were compared: drying by evaporation, lyophilisation and drying in supercritical CO2 medium. These different processes led to materials with different internal structures and porosities. The impact of these structures was evaluated in terms of swelling capacity in various media, including a simulated pancreatic environment, but also in terms of enzymatic resistance and release of an active molecule. Taking into account the obtained results, drying by evaporation was identified as the most appropriate process. In a second part, poly (N-isopropylacrylamide) (PNIPAM) was synthesised by controlled polymerisation (RAFT) in order to be grafted onto the absorbent matrix surfaces. PNIPAM is a thermosensitive polymer with bioadhesive properties which depend on the temperature. This polymer is usually bioadhesive above its lower critical solution temperature (LCST), around 32 ° C. In this study, the molar mass and the grafting density of PNIPAM are the two main parameters studied for the surface modifications. Finally, the surface properties of the grafted matrices were characterised. In vitro, the materials showed thermosensitive bioadhesive properties, with a cellular bioadhesion mainly observed above the LCST. However, ex vivo tests exhibited higher bioadhesion on porcine organs at lower temperatures. This study led to the development of absorbent biomaterials with thermoregulated surface properties. Further understanding of the relationship between surface properties and in vivo bioadhesion would allow the optimisation of the thermoregulated surface properties
Lebouc, Fanny. "Synthèse et caractérisation de polymères à base de chitosane : chitosane greffé poly(éthylène glycol) et chitosane phospahté." Caen, 2004. http://www.theses.fr/2004CAEN2001.
Повний текст джерелаBoulila, Salha. "Comportement "in vitro" et "in vivo" de verres composites poreux : assimilation osseuse, explorations physiologiques et physico-chimiques." Thesis, Rennes 1, 2016. http://www.theses.fr/2016REN1S105/document.
Повний текст джерелаThe application of biomaterials is increasingly widened. Medical progress suggest the use of biomaterials (bioactive glasses, apatites,..) as implants according to the need of the body. The aim of our work is to highlight the biological influence of organic molecules (bisphosphonates, biopolymers and antibiotics) incorporated into matrix of bioactive glasses. Similarly, our study aims to optimize the best synthesis and combination technique of bioactive glasses to these molecules. The detoxification of male rats strain "Wistar" exposed to nickel chloride by a synthetic apatite also has been the object of this work. Following the bone loss induced, we have demonstrated that the use of antibiotics associated with bioactive glass as bone implants, in ovariectomised rats, eliminates some adverse effects systemic. This has been highlighted by the evaluation of biochemical and histological parameters of liver and kidney. Any significant changes in comparison with those of the negative control was revealed. The in vitro study showed in the one hand that the introduction of Chitosan and especially of the antibiotic in the glass matrix can increase antibacterial activity. This in vitro study showed in the other hand that the Ciprofloxacin induces a negative effect on osteoblastic and endothelial cells. This effect is local when it has been an in vivo experiments. This is highlighted by the oxidative status evaluation. Markers of bone turnover, bone histology and physicochemical parameters show the retarding effect of this antibiotic on the dissolution of the implant and consequently on its bone formation. Synthesis by sol-gel method causes a more important bioactivity than melting. The bioactivity of elaborated bioactives glasses will differ depending on the molecule introduced. It is reduced in the case of combination of Clodronate and Ciprofloxacin in vitro and in vivo. While, Polyvinyl Alcohol and especially Chitosan modify the kinetic of the bioactivity in vivo. Concerning the hydroxyapatite, we tried to explore its detoxifying effect in rats receiving nickel chloride. Our results showed that nickel induces an oxidative stress in the liver, kidney, spleen and red cell pellet. Physiological disorders were observed in rats exposed to nickel. However, implantation of hydroxyapatite protects rats intoxicated by nickel against its toxic effects by decreasing the stress status. The used biomaterial is effective to correct ferric phosphate balance, protect kidney and liver function, reduce level of bone nickel and correct anemia
D'Almeida, Mélanie. "Synthèse et caractérisations physico-chimiques et biologiques de revêtements implantaires bioactifs." Thesis, Lyon 1, 2014. http://www.theses.fr/2014LYO10297/document.
Повний текст джерелаIn the past years, population requirement for dental care service increased. More precisely, replacement of missing tooth using dental implant is now a common intervention. As implant provides an artificial root, this procedure is permanent. The failure of the placement procedure is mainly due to an inflammatory disease: peri-implantitis. This disease leads to the death of bone tissues surrounding the dental implant. Today only curative solutions are available, and no implants can prevent bacterial development. It appears that preventing post-surgical complications by designing antibacterial implants is now a public health issue. To achieve this goal, we evaluate in this thesis different solutions to design bioactive implant coatings. We focused our work on coating of a model titanium surface by a bioactive polymer: chitosan. Polymer binding on the substrate is achieved by covalent link using a coupling agent. We described each step of the coating synthesis and characterized its biological properties using both surface chemistry analysis and cell biology techniques. We studied its behavior in an acid environment and analyzed its biological and antibacterial properties in vitro. Results of this work were used to select the bioactive coating with the best properties for the intended application, particularly due to its resistance in acidic condition and its antibacterial activity against common bacteria
Essabti, Fatima. "Mise en œuvre de nanocomposites à matrice chitosane pour renforcer l’imperméabilité aux gaz de films d’emballage alimentaire." Thesis, Paris, ENSAM, 2018. http://www.theses.fr/2018ENAM0059/document.
Повний текст джерелаIn order to protect food, the packaging industry performs a film coating with a very thin polymer layer to increase its gas barrier properties. The major problem of these coatings is that they are generally made of poly(vinylidene chloride) which leads to a toxic gas production during incineration. In view of the rapid change of the global environmental restrictions that become quite stringent, bioplastics seem promising alternatives. In this context, this thesis deals with a fundamental study of poly(ethylene terephthalate) films coated with a polysaccharide: chitosan. Chitosan offers good barrier properties in dry conditions. However, its application in the packaging is limited because of its hydrophilic character. Therefore, the main goal of our work is on one hand to enhance the dry barrier properties of the material through adding nanoclays and on the other hand to improve its resistance to moisture by incorporating palmitic acid by grafting it to the chitosane backbone. The incorporation efficiency of vermiculite was confirmed by DLS, DVS and XRD. A barrier improvement factor (BiF) of about 100 for helium and more than 10 for dioxygen with the addition of 50% vermiculite was obtained under dry conditions. The grafting of palmitic acid has been confirmed by FTIR spectroscopy, ATG, DSC and RMN. The results of helium permeability measurements showed an improvement of the barrier factor (BIF) of 2 in the case of a chitosan-grafted-palmitic acid layer with 60 weight% of vermiculite compared to the uncoated PET at 98% RH
Becerra, Medina José Antonio. "Films mixtes chitosane / protéines : interactions, morphologie et propriétés macroscopiques." Thesis, Lyon 1, 2012. http://www.theses.fr/2012LYO10133.
Повний текст джерелаThis work concerns the elaboration, semicrystalline microstructure and properties study of chitosan films for application of release of active principle. The semicrystalline microstructure of chitosan films strongly influences their physicochemical and functional properties, so their control becomes very important for the aimed application. In this context, we have performed a systematic study by X-ray diffraction on chitosan films varying different parameters that influence their semicrystalline microstructure, particularly, the degree of acetylation, the elaboration routes, the neutralization state, the counter-ion nature and the water content before neutralization. We have achieved to control the semicrystalline microstructure by the combination of these parameters. Furthermore, the study of the molecular mobility behaviour was carried out showing the different relaxation processes present in the chitosan films. A viscoelastic study by mechanical spectroscopy showed hydrophilic/hydrophobic transitions as a function of he thermal treatment. This study showed that the degree of acetylation does not have a strong influence on the molecular mobility in the chitosane films. Finally, we have conducted a study of swelling of chitosan film in relation to the semicrystalline microstructure. Then, a model protein (Ovalbumin) has been incorporated to study its interaction with chitosan in the solid state (in the film) and in solution (after release) and in order to evaluate its release
Diallo, Mamoudou. "Préparation et caractérisations physicochimiques et biologiques de surfaces modifiées par du chitosane." Thesis, Lyon, 2018. http://www.theses.fr/2018LYSE1083/document.
Повний текст джерелаThe surface modifications have been carried out in this thesis by two different routes: by physisorption of chitosan chains with different molecular parameters onto silicon surfaces (spin coating of homogeneous acidic solutions) and grafting of propargyl- terminated chito-oligosaccharides chains onto silicon surfaces (grafting to). The first study case was to understand the relationship between the physicochemical properties of chitosan films and the molecular parameters, and to find the impact of these physicochemical properties and molecular parameters on the biological responses. To this end, the physicochemical properties such as the wettability, morphology, chemical and physical structure of chitosan films on the one hand, and the bacteria adhesion and spreading on chitosan films on the other hand, have been characterized. In this study, we have also considered the effect of the type of acid used when solubilizing the chitosan on the films neutralization as well as the film ageing effects on the physicochemical properties. At the end of the study, the biological response of the chitosan films showed more sensitivity towards the chitosan molecular parameters than towards the physicochemical properties of the films. The aim in the second case of surface modification was to functionalize the silicon surfaces with chito-oligosaccharides by the “grafting to” method. It was conducted in three steps: silanisation, azidation and grafting of chito-oligosaccharides. All these steps were validated one by one by carrying out various characterizations using ellipsometry, tensiometry, AFM, infrared spectroscopy and TOF-SIMS spectrometry
Hansson, Annasara. "Développement et évaluation in vitro d’un dérivé de chitosan fonctionnalisé avec des peptides RGD pour la cicatrisation." Thesis, Lyon 1, 2012. http://www.theses.fr/2012LYO10182/document.
Повний текст джерелаThe aim of the work presented in this thesis, was to develop functionalizednanoparticles with the ability to induce adhesion and migration in normal humankeratinocytes. Using particulate systems to promote and support cell adhesion andmigration in epidermal restoration is a novel approach of tissue engineering.In this view, a water-soluble chitosan derivative functionalized with RGD peptideswas developed. Nanoparticles were formed through complex coacervation betweenthe cationic chitosan derivative and the anionic chondroitin sulfate. The particulatesystem was evaluated in vitro for its ability to change phenotype in cells.In the evaluation of the novel hybrid polymer, the successful synthesis wasconfirmed by the absence of cytotoxicity and a preserved bioactivity specific to theRGD-moieties. Both the polymer and the particles formed thereof induced celladhesion and spreading in human dermal fibroblasts, proving the concept ofbioactive nanoparticles. However, when investigating the interaction between thenanoparticles and keratinocytes, no clear conclusion could be drawn and furtherassays are required. To summarize, a bioactive particulate system was developed. The choice of RGDpeptides to induce migration in keratinocytes needs to be re-evaluated and higherconcentrations, mixtures of adhesion peptides or other adhesion peptides might beconsidered for further investigations
Poret, Karine. "Ciment phosphocalcique et chitosane : élaboration et caractérisation d'un composite minéral-organique." Toulouse 3, 2005. http://www.theses.fr/2005TOU30046.
Повний текст джерелаThis study concerns to the preparation and the physico-chemical and biological properties of an organic-mineral composite for orthopedic use, formed with a natural biopolymer and synthetic phosphocalcium cement. The first part of the work deals with general information on phosphocalcium cements, chitosan and crystallization. The second part presents in the study of the physicochemical behaviour of cements with chitosan. Chitosan can be added either to the liquid phase, or to the solid phase, of the cement. The chemical transformation of the cements is not disturbed by the addition of chitosan. The setting time of the cements is modified according to the mode of incorporation and the quantity of chitosan added. The compression properties of the cements were studied. For a certain quantity and/or type of chitosan, the compressive strength of the cements was preserved or improved. The third part involves the study of the interactions between chitosan and octocalcium phosphate. The method used was constant composition crystal growth. The last part presents the results of the in vivo studies carried out at Haifa University (Israel)
Martinez, Ruvalcaba Agustin. "Rhéologie des solutions de chitosane et des hydrogels de chitosane-xanthane." Thèse, Université de Sherbrooke, 2001. http://savoirs.usherbrooke.ca/handle/11143/1726.
Повний текст джерелаSaucedo, Medina Teresa Imelda. "Adsorption de l'uranium et du vanadium sur chitosane et chitosane modifié." Aix-Marseille 1, 1993. http://www.theses.fr/1993AIX11049.
Повний текст джерелаSupper, Stéphanie. "Development and characterization of parenteral in situ gelling chitosan/glucose-1-phosphate depot systems for controlled drug release." Thesis, Strasbourg, 2013. http://www.theses.fr/2013STRAF048.
Повний текст джерелаThe aim of this work was to develop a new parenteral in situ forming depot (ISFD) system for the controlled delivery of drugs. Chitosan (CS)-based systems that undergo sol / gel transition upon heating at physiological temperature were selected among the different categories of ISFDs due to their well-known biocompatibility and biodegradability. After an overall review of the recent progresses on standard CS-based ISFD systems, the synergistic mechanisms underlying the temperature-induced gelation of the CS / gelling agent systems were investigated through comprehensive rheological studies completed by 31P-NMR measurements. These investigations emphasized the key role of the polyol part of the gelling agent. The next step consisted in developing a new system combining CS and glucose-1-phosphate (G1-P). The physico-chemical characteristics and storage stability of this system were investigated. The results highlighted a sol / gel transition under physiological conditions and improved storage stability compared to the standard CS / glycerophosphate system. Local tolerability studies of the hydrogels in rats showed that the system was reasonably well tolerated. Finally, the last chapter, dedicated to the study of the in vitro release behavior of several model compounds, emphasized the ability of the polymeric CS / G1-P network to sustain the release of the incorporated substances
Venault, de Bourleuf Antoine. "Elaboration d'hydrogels composites chitosane/charbon actif à visée cicatrisante par procédés d'inversion de phase." Thesis, Montpellier 2, 2010. http://www.theses.fr/2010MON20048/document.
Повний текст джерелаChitosan/Activated carbon composite hydrogels were prepared by phase separation induced by (i) immersing the polymeric solution in a non-solvent solution (wet process) and (ii) exposing the polymeric solution to non-solvent vapors (VIPS process). The multi-scale characterization approach (SAXS, WAXS, MEBE, storage modulus, diffusion tests) did not evidence any influence of the contact mode on the functional properties of the gels. Final structures are homogeneous, porous and amorphous. They are suitable to constitute the wound dressings layer in contact with eschar-like sores. An innovative chitosan gelation model was developed coupling mass transfers, heat transfers and chemical reactions. It permitted to forecast gelation times and concentration profiles. Simulation also corroborated the non-influence of the process on the final structuring of the matrices, analyzing transfers throughout the elaboration
Hijazi, Nibal. "Développement de composites nanostructurés à base de biopolyesters et de nanoparticules de chitosane générées par des procédés assistés par CO2 supercritique." Thesis, Ecole nationale des Mines d'Albi-Carmaux, 2014. http://www.theses.fr/2014EMAC0016/document.
Повний текст джерелаIn a logic of eco-design and sustainable development, many works aim to study the bio-sourced polymers. Among these studies, a promising concept consists in structuring materials at micro and nanoscales while enhancing some of their properties, the objective being the creation of original materials with improved functional properties and performance. In this context, particular attention has been paid to the use of supercritical carbon dioxide (sc-CO2). Its ability to dissolve into many polymers in large quantities and thus to change their properties (viscosity, interfacial tension, ...), can improve both the composite material and its manufacturing process. This project focuses on the development of nanostructured biopolymers and addresses two main issues: (1) the synthesis of biopolymer nanoparticles (in this case, chitosan), and (2) the development of nanostructured biopolymers. The first step consisted in designing and developing new processing methods to generate biopolymer nanoparticles, using sc-CO2 as antisolvent agent or as dissolving and atomizing agent. For the second step, poly (lactic acid) PLA and poly (hydroxybutyric-co-hydroxyvaleric acid) PHBV based composite films were prepared by a hot-melt process by twin-screw extrusion of the nanoparticles and the matrix. Thermal, molecular and structural analysis, as well as morphological and particle size distribution studies allowed a good characterization of the biocomposite films
Qurashi, Muhammad Tariq. "Preparation and characterisation of membranes of chitosan and modified chitosan." Thesis, Queen's University Belfast, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.335584.
Повний текст джерелаKasaai, Mohammad Reza. "Depolymerization of chitosan." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape2/PQDD_0026/NQ51261.pdf.
Повний текст джерелаDupasquier, Florence. "Hydrogels physiques de chitosane pour la régénération in vivo du tissu cutané après brûlures du troisième degré." Phd thesis, Université Claude Bernard - Lyon I, 2011. http://tel.archives-ouvertes.fr/tel-00830801.
Повний текст джерелаDelas, Tim. "Formulation et stabilisation de complexes colloïdaux de polyélectrolytes à base de chitosane et de siRNA." Thesis, Bordeaux, 2021. http://www.theses.fr/2021BORD0071.
Повний текст джерелаThe presence of strong electrostatic interactions between nucleic acids such as DNA, RNA and polycations leads to the formation of colloidal particles called polyelectrolyte complexes (PECs). This approach, which allows the formation of non-viral vectors for genetic material delivery, has been the subject of numerous studies based on the use of chitosan as polycation. In the framework of this thesis, the latter was studied for its complexing properties towards small interfering RNA (siRNA). First, chitosan oligosaccharides (COS) were studied for their solution properties and complexation properties with siRNA. The effect of chain length on the solubility of chitosan and their complexing behaviour was demonstrated. Subsequently, the colloidal stability of PECs formed between chitosan and siRNA under physiological conditions was addressed. As the deprotonation of chitosan is redhibitory for the stability of the complexes, it was shown that the introduction of zinc ions in the formulation of complexes allowed to improve their stability at physiological pH. Moreover, the increase in the degree of acetylation of chitosan also allowed a clear improvement in the stability of the complexes at physiological salt conditions. With the introduction of zinc, a study of the interactions between metal ions and siRNA was also carried out and was able to highlight the strong interactions involved between metal ions and siRNA. Finally, a new synthesis leading to the formation of a new chitosan-based copolymer was carried out, making it possible to obtain as yet unexplored chitosan-based structures such as micelles or conjugate-type structures
Chedly, Jamila. "Biomatériau à base de chitosane pour la restauration de la moelle épinière traumatique de rat : analyses anatomiques et fonctionnelles." Thesis, Paris 6, 2016. http://www.theses.fr/2016PA066338.
Повний текст джерелаRegeneration after traumatic spinal cord injury generally fails due to a cascade of cellular and molecular events, including blood-spinal cord barrier breakdown,persistent and uncontrolled inflammation, and glial scarring and cavity formation combined with the presence of axon growth-inhibitory molecules. While efficient therapies are still lacking, recent progress in the design of implantable biomaterials may well open up new possibilites for their development. Chitosan hydrogels (hCh) seem particularly promising as their biological properties can be fine-tuned, notably by their degree of acetylation (DA). In the context of a rat dorsal spinal cord hemisection, I have tested different formulations of fragmented hCh for their ability to integrate into lesioned host tissue without creating additional inflammation, or excessive astrocytic reaction. Thus, I found that implantation of hCh particles of 4% DA allows for tissue reconstruction by attracting different cell types and recreating a functional vasculature. Importantly, it modulates the inflammatory response, favoring polarization of invading macrophages towards the M2 phenotype. In lesioned-implanted animals, the glial scar is less fibrous, astrocyte processes are mainly oriented towards the lesion and accompany a robust regrowth of fibers, whose origin was identified by axon tracing and immunohistochemistry. Many of these fibers are myelinated or ensheathed by Schwann cells, maintained at long term in the implant. Finally, this structural remodeling is associated with significant, long-lasting recovery of locomotor function, as I have shown by open-field and gait analysis
Venter, Chrizelle. "Chitosan and quaternised chitosan polymers as gene transfection agents / Chrizelle Venter." Thesis, North-West University, 2005. http://hdl.handle.net/10394/1015.
Повний текст джерелаThesis (Ph.D. (Pharmaceutics))--North-West University, Potchefstroom Campus, 2006.
Ciobanu, Bogdan Constantin. "De nouveaux biomatériaux polymères complexes pour la modélisation de la cinétique de libération de médicaments." Thesis, Pau, 2013. http://www.theses.fr/2013PAUU3014/document.
Повний текст джерелаThe main objective of the PhD thesis entitled “Complex polymeric biomaterials for modeling the drug release kinetics” was to bring contributions in modeling the release kinetics of active ingredients from polymer-drug systems, attempting to reduce the "burst effect"' and increase the release time. The basic idea of the thesis was, in a first stage, the encapsulation of the drug in liposomes -lipid vesicles capable of drug transport- and their subsequent inclusion in polymeric hydrogels in the rationale of creating two "barriers" in drug release process. First, obtained hydrogels are based on chitosan/gelatin and chitosan/poly(vinyl alcohol) partly covalently crosslinked with glutaraldehyde and dominantly ionically with anion sulfate or tripolyphosphate. A second category is based on chitosan hydrogels, alone or in combination with poly(vinyl alcohol), crosslinked with tannic acid through numerous hydrogen bonds. Hydrogels were characterized structurally, morphologically, in terms of the behavior in aqueous media and thermal stability, the qualities of biomaterial (hemocompatibility and cytotoxicity), the ability to include and release a model compound (calcein) free or encapsulated in liposomes. Dependence of properties (swelling, release of soluble compounds included) on the preparation process parameters (amount of crosslinker, polymers ratio used, chitosan molecular weight) is established. Performing calcein release kinetic studies (calcein included directly in hydrogels or encapsulated in liposomes subsequently dispersed in hydrogels) proves the correctness of the starting hypothesis: whatever type of crosslinking applied for the preparation of hydrogels, the release of calcein from complex systems (hydrogel-liposomes-calcein) is much delayed without manifesting practically "burst effect". The paper concludes with a chapter with modeling the release kinetics from the studied systems and with the Conclusions and Perspectives. Given the potential application of such hydrogels in the form of films for treating skin conditions, preliminary results of levofloxacin release from a transdermal system that simulates human dermis are shown
Carolan, Christina Anne. "Chitosan and chitosan derivatives for use in membrane and ion-exchange technology." Thesis, Queen's University Belfast, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.238984.
Повний текст джерелаIshizawa, Higuchi Claudia Inés. "Hydrogel à base de chitosane-xanthane : une matrice pour l'inclusion et le relargage de médicaments = Chitosan-xanthan hydrogel : a matrix for the inclusion and the delivery of drugs." Sherbrooke : Université de Sherbrooke, 2002.
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