WorldCat Identities

Picton, Luc

Overview
Works: 21 works in 27 publications in 2 languages and 36 library holdings
Roles: Other, Thesis advisor, Author, Opponent
Classifications: QD505, 541
Publication Timeline
.
Most widely held works by Luc Picton
Propriétés en solution aqueuse d'éthers cellulosiques associatifs. Influence des cosolutés et de la température : conséquences rhéologiques by Luc Picton( )

2 editions published in 1996 in French and held by 3 WorldCat member libraries worldwide

L'hydroxyéthylcellulose hydrophobiquement modifiée (HMHEC) est un polymère associatif industriel obtenu par greffage d'une très faible quantité de chaînes hexadécyle sur le polymère précurseur (HEC). En solution aqueuse, l'association des groupes hydrophobes confère au polymère modifié des propriétés qui diffèrent profondément de celles des précurseurs. En régime dilué, le caractère associatif conduit à la formation d'agrégats intermoléculaires et/ou d'interactions intramoléculaires. Au-delà d'une concentration critique, qui délimite le début du régime semi-dilué, les associations deviennent essentiellement intermoléculaires et les propriétés épaississantes augmentent considérablement. Les solutions plus concentrées présentent alors une structure enchevêtrée tridimensionnelle enrichie de zones de jonctions hydrophobes fluctuantes, responsables de l'apparition d'un caractère viscoélastique. Les associations hydrophobes, de faible énergie, sont facilement détruites sous l'influence d'une contrainte de cisaillement et on observe un caractère rhéofluidifiant. Le temps nécessaire à la reformation réversible des associations se traduit par un phénomène de thixotropie. Les associations hydrophobes sont induites par la structure de l'eau. L'amélioration de l'organisation des molécules d'eau favorise les mécanismes d'associations. Ainsi, les sels lyotropes (NaCl) renforcent les associations hydrophobes, tandis que les sels chaotropes (KSCN) les affaiblissent. La présence d'éthanol entraîne la rupture des associations par une meilleure solvatation des groupements apolaires. D'autre part, la température semble favoriser l'établissement des associations en accord avec leur caractère endothermique
Nouveaux hydrogels à base de polysaccharide obtenus par voie biomimétique ou par photoréticulation. by Ahdi Hadrich( )

2 editions published in 2019 in French and held by 2 WorldCat member libraries worldwide

Dans un contexte de démarche écoresponsable et pour répondre aux exigences de biocompatibilité notamment dans les applications cosmétiques et biomédicales, nous avons développé de nouveaux hydrogels à base de polysaccharides neutres et anioniques en utilisant deux voies originales. La 1ère approche est biomimétique et a consisté à mimer un phénomène d'élaboration naturelle d'hydrogels que l'on retrouve chez certains végétaux pour lesquels une enzyme, la laccase, permet de créer des liens de réticulation par dimérisation des composés phénoliques (en l'occurrence de l'acide férulique FA) présents sur les arabinoxylanes des mucilages des graines de céréales par exemple. Notre travail a ainsi consisté à greffer de l'acide férulique via deux chimies différentes de type imidazole et carbodiimide respectivement pour des polysaccharides neutres ou anioniques. Nous avons ainsi fonctionnalisé trois polysaccharides : le pullulane ou PUL (neutre modèle), le carboxyméthylpullulane ou CMP (anionique modèle) et l'acide hyaluronique ou HA (anionique d'intérêt). Des taux de greffage compris entre 2 et 25% ont été obtenus. L'étude physicochimique en régimes dilué et semi-dilué a permis de mettre en évidence un comportement associatif lié au caractère amphiphile des polysaccharides fonctionnalisés. La réticulation en présence de laccase, suivie in situ en rhéologie, a été réalisée avec succès sur les différents systèmes envisagés avec des contrôles possibles de la cinétique, des propriétés mécaniques finales ou encore du gonflement des hydrogels en fonction du caractère neutre ou chargé des polysaccharides, du degré de substitution en acide férulique, de la concentration en polymère ou de l'activité enzymatique fixée. Les dérivés synthétisés ont globalement démontré des activités biologiques (antioxydante et cytocompatible) intéressantes. La deuxième approche repose sur la photoréticulation possible de polysaccharides (PUL, CMP et HA) fonctionnalisés par le greffage d'amine/acide gras mono ou polyinsaturé (oleylamine, acide oléique et linoléique) via la chimie des imidazoles. Si le pullulane modifié par l'acide linoléique à 2% s'est avéré non hydrosoluble en raison de son caractère neutre, tous les autres dérivés avec des taux de greffages de 3 et 10% ont démontré une bonne solubilité dans l'eau. Les études physicochimiques mettent en évidence un très fort caractère associatif de ces dérivés amphiphiles avec la formation de gels physiques en régime semi-dilué. La photoréticulation a été démontrée en rhéologie sous irradiation UV in situ en présence d'un photoamorceur de type Darocur 1173®. Les résultats préliminaires obtenus selon cette approche en photoréticulation ouvrent ainsi des perspectives intéressantes
Synthèse et caractérisation de dérivés amphiphiles du xanthane by Audrey Roy( )

2 editions published in 2015 in French and held by 2 WorldCat member libraries worldwide

Hydrophobically modified polysaccharides show unusual rheological and interfacial properties in solution due to the self association of hydrophobic entities grafted onto their hydrophilic backbone. Their properties are tunable according to some well known parameters, such as the length of the hydrophobic moieties or the grafting density. However, very few studies deal with the influence of the backbone conformation on the properties of such systems in solution. Therefore, the objective of this work is to determine the impact of the backbone rigidity on the behavior of an amphiphilic polysaccharide based on xanthan. Indeed, in solution, this polymer can adopt two different conformations depending on the experimental conditions: an ordered, rigid helix or a disordered, flexible coil. Hydrophobic moieties have been grafted on xanthan either under its ordered and disordered conformation. Chains modified under the ordered conformation remain ordered and rigid after grafting and the overall properties are controlled by the high rigidity of the polymer backbone. On the contrary, macromolecules grafted under the disordered form show a more flexible conformation in solution. As a result, the organization of these derivatives is mainly controlled by the attractive interactions between the grafted moieties
Effect of biopolymer addition on the formulation and properties of an oil-in-water microemulsion by Safia Djedri( )

1 edition published in 2014 in English and held by 2 WorldCat member libraries worldwide

Polysaccharides fonctionnalisés par des composés d'origine naturelle aux propriétés antioxydantes et antibactériennes. by Marie-Carole Kouassi( )

2 editions published in 2017 in French and held by 2 WorldCat member libraries worldwide

The works described in this manuscript concern the development of natural and water soluble preservatives based on polysaccharides grafted with molecules of plant origin (from phenolic structure). The aim consists in developing new systems with antioxidant and/or antibacterial properties together with rheological ones for cosmetic and/or food application fields. For this purpose, aminoguaiacol (derived from guaiacol) was chemically grafted onto a polysaccharide (carboxymethylpullulan) in various proportions (between 5 and 58 %). The physicochemical studies in dilute and semi-dilute saline media put forward an associative character (of polysoap type) of the most grafted derivatives, with predominant hydrophobic intramolecular interactions which are limiting for rheology. All synthesized products have demonstrated antioxidant and antibacterial properties. The associative character (i.e., the presence of hydrophobic microdomains) was found to be favorable to the antioxidant activity, with the best activity for the most grafted aminoguaiacol derivative (58%). On the contrary, the associative behavior limited the antibacterial activity, in this case, the least grafted derivative (5%) demonstrated the best antibacterial activity, due to best availability of the grafted moieties. In order to improve the biological and/or rheological properties, this grafting approach of aminoguaiacol has been extended to another anionic polysaccharide (alginate), more rigid than carboxymethylpullulan with promising results notably as concerns rheology
Nouveaux complexes polyélectrolytes à amphiphilie contrôlée à base de polysaccharides modifiés by Anne-Sophie Pépin( Book )

1 edition published in 2010 in French and held by 2 WorldCat member libraries worldwide

Polyelectrolyte complexes (PEC) are obtained by self-assembling between a polycation and a polyanion. Commonly, most of the PECs studied are synthetic and they present no biocompatibility. This situation changes when the complementary polyelectrolytes are natural polymers, like DNA or polysaccharides. It is the aim of this study to prepare some natural PECs and to observe the behavior of the system depending on the concentration of the polyelectrolytes, pH and ionic strength, in relation to application. Our PECs are elaborated starting from two functionalized polysaccharides : an anionic pullulan (carboxymethyl pullulan) whose synthesis is presented elsewhere in detail4 and a cationic dextran (diethylaminoethyl dextran), a commercial product. It is possible to obtain a wide range of PECs by controlling the functionalization of pullulan and the degradation of both polysaccharides. The change in the density of charge and the molecular weight of polymer precursors give different PEC systems. The variation in the solubility, the charge ratios and the molecular weight of these PECs are studied along with parameters like size, turbidity, zeta potential, viscosity and interaction characteristics (thermodynamics). With this study, we are able to obtain PECs in which the structure can be modulated by external stimuli. This investigation forms the basis for the next experiments on purpose to obtain amphiphilic polyelectrolyte complexes by grafting hydrophobic chains on the anionic pullulan. These amphiphilic systems are well suited to encapsulate hydrophobic compounds for subsequent controlled release
Enhancement of the Solubility and Efficacy of Poorly Water-Soluble Drugs by Hydrophobically-Modified Polysaccharide Derivatives by Widad Henni-Silhadi( )

1 edition published in 2007 in English and held by 2 WorldCat member libraries worldwide

Effet de l'enchevêtrement et du greffage d'une enzyme sur son activité : étude sur le système pullulanase-pullulane-alginate by Ghina Ali( Book )

1 edition published in 2012 in French and held by 2 WorldCat member libraries worldwide

The aim of this work is to study the immobilization and the enzyme activity on a functionalisable polysaccharide support. The system used is pullulanase-pullulan-alginate. The study of free pullulanase behaviour confirmed a process endo. The assay of reducing extremities and the size exclusion chromatography coupled with light scattering and refractometry allow determining all macromolecular characteristics (Mn, Mw, % maltotriose, and its multiples) during hydrolysis. The presence of alginate slows the hydrolysis kinetics of the free enzyme, in particula whe alginate concentrations are above the critical entanglement concentration (C*). The amount of oligosaccharides is not dependent on the alginate concentration and the endo enzyme behaviour is not modified by the entanglement in the medium. The covalent immobilization of pullulanase on alginate in the presence of activator was carried out via an amide bond. The immobilized enzyme retains its catalytic activity on long time and its mode of action is modified with a tendency to break preferentially the links near to the chain ends. The kinetic parameters of free pullulanase, in the presence of alginate and immobilized were determined by Isothermal Titration Calorimetry. Hydrolysis monitoring shows that the affinity of pullulanase for its substrate, pullulan is affected by the presence of alginate and its grafting
Hydrogels Based on Pullulan Crosslinked with sodium trimetaphosphate (STMP): Rheological study by Stéphane Lack( )

1 edition published in 2004 in English and held by 2 WorldCat member libraries worldwide

The red microalga Flintiella sanguinaria as a new exopolysaccharide producer by Clément Gaignard( )

1 edition published in 2018 in English and held by 2 WorldCat member libraries worldwide

Influence of alkyl chains length on the conformation and solubilization properties of amphiphilic carboxymethylpullulans by Widad Henni-Silhadi( )

1 edition published in 2008 in English and held by 2 WorldCat member libraries worldwide

Détermination des natures des intéractions entre polymères en solution aqueuse à l'échelle moléculaire par spectroscopie de fluorescence by Alexandre Cordinier( )

2 editions published in 2020 in French and held by 2 WorldCat member libraries worldwide

Molecular interactions are everywhere in daily life. Numerous studies were made in the field of supramolecular chemistry on these low-energy non-covalent interactions at the solid state but less were carried out in order to characterize them in solution. That is why this research project was brought to life in order to set up a methodology allowing to characterized molecular interactions in solutions and mixtures of water-soluble polymers and to keep a non disturbed studied system. To achieve ths goal, we chose to use fluorescence spectroscopy. After a large selection, two moleculars probes were selected; ANS for dipole-dipole and hydrophobic interactions and 3HQ-Bf for H-bonds. As a support to study the interactions, xanthan/galactomannan systems, widely studied at the macroscopic scale were analyzed at the molecular scale to better understand xanthan/galactomannan association. Once the methodology tested on a simple system, we were able to characterize molecular interactions in aqueous xanthan/galactomannan solutions and mixtures. Furthermore, molecular synergies were brought to light in the case of hydrophobic interactions and H-bonds. Dipole-dipole interactions may play a major role in the background rather than in the foreground
Pullulan-STMP hydrogels: a way to correlate crosslinking mechanism, structure and physicochemical properties by Virginie Dulong( )

1 edition published in 2011 in English and held by 2 WorldCat member libraries worldwide

Hydrogels à base de biopolymères : applications en ingénierie tissulaire de la peau by Raluca Vulpe( Book )

2 editions published in 2016 in French and held by 2 WorldCat member libraries worldwide

The main objective of this PhD work was to design new hydrogels based on proteins and polysaccharides with biocompatible properties and high potential in tissue engineering in particular in the field of skin tissue regeneration and drug release. We have chosen to develop binary or ternary systems with collagen, acid hyaluronic (HA) and séricine. The originality consisted in developing new access ways of hydrogels by using non cytotoxic crosslinking agents on the contrary to the classic ways. Hydrogels from these biopolymers were so crosslinked with carbodiimides but also by using an original method thanks to the grafting of the riboflavine on biopolymers followed by crosslink under UV irradiation. The obtained hydrogels were characterized by infrared spectroscopy and NMR, swelling in water, morphology by SEM, thermogravimetric analysis and differential scanning calorimetry indicating the success of the crosslinking. The biodegradability was confirmed in particular under the enzymatic ways (collagenase and hyaluronidase). The absence of cytotoxicity was also validated. The capacity of these hydrogels in drug delivery (ibuprofen) was also confirmed. Finally a rheological study made on the carbodiimide crosslinked systems confirmed the importance of the molecular dynamics of the initial and the mixtures solutions on crosslinking kinetics and on the final structures of the hydrogels. These promising results could be used in future developments of new materials used for biomedical applications
Hydrogel poreux pour la reconstruction osseuse : élaboration, caractérisation et mise en œuvre dans un bioréacteur à perfusion by Jérôme Grenier( )

1 edition published in 2019 in French and held by 1 WorldCat member library worldwide

The reconstruction of large bone defects requires the implantation of scaffolds that are biocompatible, biodegradable and able to promote bone healing. This thesis focused on a porous biomaterial that had already demonstrated its osteo-inductive properties after implantation in rats and goats. This biomaterial is produced by freeze-drying of a chemically crosslinked polysaccharide-based (pullulan and dextran) hydrogel.First, we studied the influence of the process parameters on the properties of the biomaterial porous structure. The scaffolds were characterized at each step of the fabrication process: by dynamic rheometry during crosslinking, by electron cryo-microscopy just after freezing, by X-ray microtomography in the dry state and finally by confocal microscopy in the swollen state. It appears that the porous structure obtained at the end of freeze-drying strongly depends on the microstructure of the ice formed during the freezing stage: each pore results from the growth of one to a few crystals. Ice grains are mostly generated by secondary nucleation, this phenomenon is enhanced by the presence of the polymer network. Two parameters controlling the porous structure were particularly examined: the amount of crosslinker that reacts with the polysaccharides (which affects the correlation length of the polymer network), and the nucleation temperature at the onset of freezing. After sublimation of ice, the biomaterial becomes highly porous (92-94%).The seeding efficiency of the dried scaffolds was quantified using suspensions of narrow-sized calibrated microspheres and suspensions of cells: the seeding threshold is in the order of the average diameter of the dry pores. After swelling (occurring simultaneously with seeding), porosity is significantly lower (~ 30%) and the average diameter of the swollen pores is 2 to 4 times lower than in the dry state (depending on the crosslink density).Secondly, we investigated in vitro the interactions between the porous hydrogel scaffolds and osteo-competent cells derived from a mouse cell line. The experimental device was designed in order to mimic the physiological conditions. A perfused bioreactor was chosen because of its ability to generate a 3D environment with controlled shear stress and controlled solute concentration. Such a system should help to optimize the biomaterial while reducing the use of animal experiments. A multiscale characterization of the bioreactor tests was implemented: use of biomarkers and confocal microscopy at the spheroid and scaffold scales, magnetic resonance imaging at the bioreactor scale. We also investigated the hydrodynamics and the transport of oxygen within the bioreactor using computational fluid dynamics: fluid, hydrogel and spheroids were described at the MRI spatial resolution (i.e. 55 µm), NavierStokes equations and advection-diffusion equation were simulated using lattice-Boltzmann methods. These methods are indeed particularly suitable for complex geometries. The influence of organoid size and density on the oxygen concentration field was studied to optimize cell viability.This thesis provides key elements to control the microstructure of the porous hydrogel scaffolds and proposes a workflow to optimize the bone healing properties of the biomaterial by coupling tests in perfused bioreactors, experimental characterizations and numerical modelling
Rheological study of a new semi-rigid giant polysaccharide for the mechanical reinforcement of hydrogels by Tom Saint-Martin( )

1 edition published in 2017 in English and held by 1 WorldCat member library worldwide

Nous étudions la relation structure/propriétés d'hydrogels rigides composés d'un nouveau polysaccharide géant, le sacran. Ce nouveau polysaccharide possède une longueur de contour supérieure à 10 µm et une longueur de persistance intrinsèque d'à peu près 60 nm. Ainsi la réticulation de ces chaines polysaccharides est capable de former des réseaux dits rigides, dans lesquels la taille de maille est contrôlée par des segments de chaines rigides. A partir du sacran, des hydrogels physiques (liaisons transitoires) et chimiques (liaisons covalentes) ont été fabriqué dans l'optique d'observer des différences comportementales entre ces réseaux. La formation de réseaux rigides de sacran à être démontrée par l'utilisation de la microrhéologie non-conventionnelle par DWS permettant le suivi de la dynamique d'une chaine polymère individuelle composant le réseau. Différentes signatures rhéologiques propres à ces réseaux rigides ont été mises en évidence et des propriétés de strain-hardening ont été observées dans le régime non-linéaire des gels chimiques de sacran, et plus étonnamment des gels physiques également. Les strain-hardening observés pour les gels chimiques de sacran, grands devant ceux reportés dans la littérature, ont pu être modélisés permettant l'obtention des paramètres structurant ces réseaux et conduisant à leur durcissement
Etude des mécanismes de libération d'actifs nanodispersés : application au traitement de puits by Céline Rondon( )

1 edition published in 2010 in French and held by 1 WorldCat member library worldwide

Many thermodynamic changes occur in reservoir rock when oil is produced. These changes enable scale formation on micrometric rock pores that can block them and impede/block oil extraction. Antiscale treatment efficiency depends on minimal inhibitor concentration and product release rate in fluids downhole. In this context, we have studied two encapsulation techniques allowing us to have a sustainable release system composed of an anionic polyelectrolyte as a model additive. The first formulation consists in formation of polyelectrolyte complexes nanoparticles. In this system, active ingredient release was stimulated through medium ionic strength modulation. Under basic conditions, release takes place in particles swelling/dissociation process; whereas, under acidic condition, particles precipitate and no release can be expected. The second system we have worked on is a diluted reverse (W/O) emulsion, in which dispersed aqueous droplets contain a model additive. These systems are stable and small additive percentage is released under mechanic strain
Suivi multi-échelle in situ des réactions de polymérisation en macroémulsion par spectrométrie Raman by Elise Dropsit( )

1 edition published in 2017 in French and held by 1 WorldCat member library worldwide

The development of in situ monitoring techniques of emulsion polymerization reactions is a real current challenge. First, it may help establish relations between the structure, the physicochemical properties and the performance properties of final latexes. Moreover, it brings a better understanding of chemical and physicochemical phenomenon that happened. Easy installation, performance of measures and abundance of information gathered (from molecular to material scales) make the Raman spectroscopy an adequate technique for this kind of issue, as shown in recent studies. The main goal of that work was to demonstrate the capacity of the Raman spectroscopy to control the polymerization of styrene via macroemulsion process, in terms of smooth reaction process (conversion, ...) and final properties of the latex (stability, ...). This work was carried in the laboratoire des Matériaux Optiques, Photonique et Systèmes (LMOPS) where a polymerization pilot was implemented for the first time. The latest has been designed in order to ensure a maximum freedom for spectroscopic measurements (optical setup). Because of this special design, the first part of this work was to adapt experimental conditions, in terms of polymer latex synthesis and spectroscopic data acquisition. Thereafter, we proved that Raman spectroscopy could be a suitable technique for real time in situ conversion monitoring in the case of the polymerization of styrene via macroemulsion process. The monomer conversion monitoring has been realized in two different methods: the first one is well-known and is based on monitoring changes in the normalized Raman signal of specific band and the second one is an innovative method that is based on the Ramanshift of a common band of styrene and polystyrene. On the basis of these experimental data and using a suitable smoothing method, the polymerization rate was quantified for the first time. The results were compared to the theory of this polymerization process and previous experimental results from other experimental techniques. Whereas experimental results show similarities, they all show a deviation from the theory. Finally, an in-depth study of the impact of the heterogeneity of the reaction media on the Raman signal has been made. We have demonstrated that this latest was sensitive to elastic scattering of light by dispersed particles. The influence of elastic scattering on the intensity of the collected Raman signal makes the Raman spectroscopy a suitable method to detect a specific transition of the polymerization process: the disappearance of monomer droplets around 40 % of conversion in case of styrene
Formulation de pâtes céramiques innovantes contenant des composés organiques biosourcés by Jeremy Marie( )

1 edition published in 2018 in French and held by 1 WorldCat member library worldwide

The aim of this work is focused on the elaboration of new alumina suspensions with biopolymer additives and rheological properties adapted to the tape casting process. The suspensions used in the tape casting process are basically composed of a ceramic powder, a solvent, a dispersant, a binder and a plasticizer. These additives are usually polymers coming from the petrochemical sector which show risks for the operator health or the environment (in particular with organic solvents). Thus, natural polymers extracted from plants were identified as promising candidates in order to substitute the classical organic additives. Then, the study of the interactions between different organic additives with alumina led to a specific protocol for the formulation of aqueous alumina suspensions with these bio-polymers. Then, mechanical properties of the green and sintered tapes were evaluated in relation with the nature of bio-polymer additives. The obtained densities are close to the values reported in the litterature
Microparticules préparées par transacylation entre sérumalbumine humaine et polysaccharides estérifiés : Approche physicochimique, structurelle et fonctionnelle by Imane Hadef-Djebaili( )

1 edition published in 2015 in French and held by 1 WorldCat member library worldwide

In our laboratory, an original method of microencapsulation was developed, based on the use of a transacylation reaction, creating covalent bonds between proteins and propylene glycol alginate (PGA). The covalent bonds are created after alkalization of the aqueous phase of a W/O emulsion, without using bifunctional crosslinking reagent.The resulting microparticles, which are stable, biocompatible and biodegradable, have potential applications for the delivery of active compounds for therapeutics or cosmetics.The first aim of this work is to study the influence of the physicochemical properties of the two polymers (protein and PGA) and of their solutions, as well as the effect of the preparation parameters on the transacylation reaction and on microparticle characteristics. For this purpose, human serum albumin (HSA) was picked as a model protein and microparticles were prepared using several physicochemical conditions then characterized. Several relationships were established between the physicochemical properties of the initial solutions of the two polymers and the functional properties of the resulting microparticles.The second purpose is to replace the PGA, only polysaccharide used for microencapsulation by transacylation so far, by other natural polysaccharides in the preparation of microparticles. Given its limiting intrinsic properties, the replacement of PGA by other polysaccharidic esters seems advantageous in the field of microparticle applications.In this work, the PGA was successfully replaced by a series of semisynthetic alginate esters, and then by other polysaccharidic esters, either natural esters (pectin) or semisynthetic esters (polypectate esters and hyaluronate esters). The optimal conditions for the use of each ester were then determined
 
moreShow More Titles
fewerShow Fewer Titles
Audience Level
0
Audience Level
1
  General Special  
Audience level: 0.00 (from 0.00 for Propriéte ... to 0.00 for Propriéte ...)

Alternative Names
Luc Picton wetenschapper

Languages
French (19)

English (7)