Le lait écrémé est utilisé depuis plus d’un demi-siècle comme diluant protecteur des spermatozoïdes de mammifères. Depuis quelques années, il existe une demande grandissante pour des diluants exempts de produits d’origine animale. Toutefois, le mécanisme par lequel le lait protège les spermatozoïdes n’est pas connu, ce qui rend difficile de lui trouver un substitut. Les protéines majeures du plasma séminal de taureau, les protéines « Binder of SPerm » (BSP), sont néfastes lors de la conservation de la semence. Les spermatozoïdes sont en contact avec une grande concentration de protéines BSP qui stimulent une extraction continuelle de cholestérol/phospholipides de leur membrane plasmique. Les lipoprotéines de faible densité (LDL) du jaune d’oeuf, un autre composé utilisé dans les diluants, empêcheraient les protéines BSP de se lier à la membrane des spermatozoïdes de taureaux et de stimuler un efflux des lipides membranaires, ce qui les protégerait durant la conservation. Notre hypothèse était que les protéines du lait protègent les spermatozoïdes durant la conservation en séquestrant les protéines BSP. Premièrement, nous avons démontré par filtration sur gel qu’il y a une interaction entre les protéines BSP bovines et les protéines du lait. Le lait écrémé a été fractionné en trois fractions : F1 (alpha-lactalbumine, bêta-lactoglobuline et caséine kappa), F2 (toutes les protéines du lait) et F3 (sels, sucres et petits peptides). Les protéines BSP1 et BSP5 ont une affinité plus grande pour F1 que BSP3, tandis que toutes les protéines BSP ont une affinité pour F2. Le titrage calorimétrique isotherme a permis de confirmer l’interaction entre les protéines BSP et les protéines du lait. L’association entre la protéine BSP1 bovine et les micelles de caséines est caractérisée par une constante d’affinité (Ka) de 3.5 × 10^5 M-1 et un paramètre stoichiométrique (n) de 4,5 BSP1 pour une caséine. L’association entre la protéine BSP1 bovine et l’alpha-lactalbumine (une protéine du sérum principale), est caractérisée par un Ka de 2.4 × 10^5 M-1 et une valeur “n” de 0,8. Ces résultats indiquent que le lait protège les spermatozoïdes bovins en séquestrant les protéines BSP grâce à une interaction protéine : protéine, tandis que le jaune d’oeuf les protège grâce à une interaction protéine : lipoprotéine. Deuxièmement, nous avons démontré par filtration sur gel que les protéines homologues aux BSP bovines retrouvées dans le plasma séminal de porc, d’étalon et de bélier ont une affinité avec les protéines du lait, ce qui suggère que le mécanisme de protection des spermatozoïdes par le lait pourrait être le même chez ces espèces. Troisièmement, nous avons caractérisé l’interaction entre BSP1 bovine et les LDL du jaune d’oeuf qui a un Ka de 3.4 ± 0.4 × 10^6 M-1 et une valeur de « n » de 104 BSP1 pour une particule de LDL, indiquant qu’il existe des différences entre le mécanisme de protection des spermatozoïdes par le lait et le jaune d’oeuf. Nous croyons que les résultats présentés dans cette thèse aideront à créer de nouveaux diluants ne contenant pas de produits d’origine animale afin de cryoconserver les spermatozoïdes des mammifères. / Skim milk is being used as a protective agent for mammalian semen conservation over half a century. Recently, there has been increased interest in developing extenders free of animal products. However, it is difficult to find suitable component in order to replace milk as an extender, because the mechanisms by which milk protect sperm against cooling and freezing damages during the storage is unknown. The Binder of SPerm (BSP) proteins are the major proteins of bull seminal plasma and they are harmful during sperm storage. In fact, sperm would be in contact with a large quantity of BSP proteins that induce a continuous cholesterol and phospholipids efflux from the sperm membrane during storage. When bull sperm is diluted with an extender containing egg yolk, another compound frequently used in extender, the low-density lipoproteins (LDL) present in the egg yolk prevent the binding of the BSP proteins to the sperm membrane, thus, preventing the lipid efflux from the sperm membrane induced by the BSP proteins. Our hypothesis was that milk proteins would protect sperm during storage by binding BSP proteins. First, we demonstrated by gel filtration that bovine BSP proteins could bind the milk proteins. Skim milk was fractionated into three fractions: F1 (alpha-lactalbumin and beta- lactoglobulin, the major whey proteins and kappa-casein), F2 (mainly caseins and all other milk proteins in small amounts) and F3 (salts, sugars and small peptides). Bovine BSP1 and BSP5 have more affinity for F1 as compared to BSP3 and all the BSP proteins have affinity for F2. We confirmed the interaction between bovine BSP proteins and milk proteins by isothermal titration calorimetry. The binding of BSP1 to casein micelles is characterized by an affinity constant (Ka) of 3.5 × 10^5 M-1 and of a stoichiometric parameter for the association (n) of 4.5 BSP1 per casein. The association between BSP1 and alpha-lactalbumin (one of the major whey proteins) is characterized by a Ka of 2.4 × 10^5 M-1 and a “n” value of 0.8. These results support our contention that milk can protect sperm by preventing the BSP proteins’ binding to the sperm membrane attributable to a protein : protein interaction, while egg yolk sperm protection is attributable to a protein : lipoprotein interaction. Second, our studies showed that the homologous BSP proteins found in the boar, stallion and ram seminal plasma can bind the milk proteins. These results indicate that the mechanism of sperm protection by milk in these species should be similar to the one in bovine species. Third, we characterized the interaction between bovine BSP1 protein and LDL from hen’s egg yolk. The binding was characterized by a Ka of 3.4 ± 0.4 × 10^6 M-1 and a « n » value of 104 BSP1 per LDL particle. Our results indicated that there is difference between the mechanism of sperm protection by milk and egg yolk. We believe that the results presented in this thesis may help to create new extenders free of animal product for mammal sperm preservation in liquid or frozen state.

Thèse numérisée par la Division de la gestion de documents et des archives de l'Université de Montréal

The thesis involves computer simulation and theoretical studies of dynamics of water under confinement and structural transformation in different complex systems. Based on the systems and phenomena of interest, the work has been classified in to three major parts: I. Dynamics of water under confinement II. Dynamics of water in presence of amphiphilic solutes III. Structural transformation in complex systems The three parts have further been divided into nine chapters. Brief chapter wise outline of the thesis is discussed below. Part I deals with the dynamics of water in confined systems. In Chapter I.1, we provide a brief introduction of water dynamics inc on fined systems. We also give a brief outline of relevant experimental and theoretical techniques used to study the water dynamics under confinement. Chapter I.2 describes a model based analytical study of dynamical correlation in confined systems. Here, we introduce a novel one dimensional Ising model to investigate the propagation and annihilation of dynamical correlations in confined systems and to understand the intriguing shortening of the orientational relaxation time that has been reported for small sized reverse micelles (RMs).In our model, the two spins located at the two end cells are oriented in the opposite directions to mimic the surface effects present in the real systems. These produce opposing polarizations which propagate from the surface to the center, thus producing bulk like condition at the center. This model can be solved analytically for short chains. For long chains, we solve the model numerically with Glauber spin flip dynamics (and also with Metropolis single-spin flip Monte Carlo algorithm).We show that the model satisfactorily reproduces many of the features observed in experiments. Due to the destructive interference among correlations that propagate from the surface to the core, one of the rotational relaxation time components decays faster than the bulk. In general, the relaxation of spins is non-exponential due to the interplay between various interactions. In the limit of strong coupling between the spins or in the limit of low temperature, the nature of the relaxation of spins undergoes a change with the emergence of homogeneous dynamics, where the decay is predominantly exponential. In Chapter I.3, layer-wise distance dependent orientation relaxation of water confined in reverse micelle s(RM)is studied using theoretical and computational tools. We use both a newly constructed spins on a ring (SOR) Ising-type model with modified Shore-Zwanzig rotational dynamics and atomistic simulations with explicit water. Our study explores the size effect of RMs and the role of intermolecular correlations, compromised by the presence of a highly polar surface, on the distance (from the surface) dependence of water relaxation. The SOR model can capture some aspects of distance dependent orientation relaxation, such as acceleration of orientation relaxation at intermediate layers. In atomistic simulations, layer-wise decomposition of hydrogen bond (H-bond) formation pattern clearly reveal that the H-bond arrangement of water at a certain distance away from the surface can remain frustrated due to interaction with the polar surface head groups. We show that this layer-wise analysis also reveals the presence of a non-monotonic, slow relaxation component which can be attributed to the frustration effect and is accentuated in small to intermediate size RMs. For larger RMs, the long-time component decreases monotonically from the interface to the interior of the RMs with slowest relaxation observed at the interface. In ChapterI.4, we present theoretical two dimensional infrared spectroscopic (2D-IR) studies of water confined within RMs of various sizes. Here we focus again mainly on the altered dynamics of confined water by performing a layer-wise decomposition of water. We aim to quantify the relative contributions to the calculated 2D-IR spectra by water molecules located in different layers. The spectra of 0-1 transition clearly show substantial elongation along the diagonal, due to in homogeneous broadening and incomplete spectral diffusion, in the surface water layer of different size of RMs studied in this work. Our study reveals that the motion of the surface water molecules is sub-diffusive, establishing the constrained nature of their dynamics. This is further supported by the two peak nature of the angular analogue of the van Hove correlation function. With increasing system size the motion of water molecules becomes more diffusive in nature and the structural diffusion is observed to be almost completed in the central layer of larger RMs. Comparisons between experiment and simulation help establishing the correspondence between the spectral decomposition available in experimental 2D-IR with the spatial decomposition of simulated 2D-IR. Simulations also allow a quantitative exploration of the relative role of water, sodium ions and sulfonate head groups in irrational dephasing. Interestingly, the negative cross correlation between forces on oxygen and hydrogen of O-H bond in bulk water significantly decreases in the surface layer of different RMs. This negative cross correlation gradually increases in the central layer with increasing size of the RMs and this is found to be partly responsible for the faster relaxation rate of water in the central layer. Part II consists of two chapters and focuses on the dynamics of water in presence of amphiphilic solutes. In Chapter II.1, we present a brief introduction of water – DMSO binary mixture and various anomalous properties of the same. In Chapter II.2, we present theoretical IR study of water dynamics in water–DMSO binary mixtures of different compositions. We show that with increasing DMSO concentration, the IR absorption peak maxima show the presence of structural transformation in similar concentration range, observed in earlier studies. Analysis of H-bonded network near hydrophilic and hydrophobic part of DMSO also suggests that average number of hydrogen bonds near the hydrophobic parts possess maxima at the same concentration range. We also show that with increasing DMSO concentration water dynamics becomes very slow. This has been supported by the diagonal elongation of the 2D-IR spectra and also the slow decay of frequency fluctuation correlation n function (FFCF) and the orientation time correlation function (OTCF). The decoupling of the OTCF establishes that water-DMSOH-bond is much stronger than that of water-water. The last part (Part III) consists of three chapters that deal with structural transformation in various complex systems. In Chapter III.1, we introduce polydisperse systems and present existing theoretical, computer simulation and experimental studies. It also contains the importance and diversity of polydisperse system in nature. In Chapter III.2, we present computer simulation study of melting of polydisperse Lennard-Jones (LJ) system with Gaussian polydispersity in size. The phase diagram reproduces the existence of an early temperature in variant terminal polydispersity (δt0.11), with no signature of re-entrant melting. The absence of re-entrant melting can be attributed to the influence of attractive part of the potential on melting. We find that at terminal polydispersity the fractional density change approaches zero that seems to arise from vanishingly small compressibility of the disordered phase. At constant temperature and volume fraction system undergoes a sharp transition from crystalline solid to disordered state with increasing polydispersity. This has been quantified by second and third order rotational invariant bond orientational orders as well as by the average inherent structure energy. The translational order parameter also indicates similar structural change The free energy calculation further supports the nature of the transition. The third order bond orientational order shows that with increasing polydispersity, local cluster favors more icosahedral-like arrangements and thus the system loses its crystalline symmetry. In Chapter III.3, we present study of phase transition and effect of confinement on it in SOR model. This system is similar to our SOR model discussed in Chapter I.3. The spins execute continuous rotation under a modified XY Hamiltonian. In order to understand the nature of phase transition in such confined spin systems we have performed extensive Monte Carlo simulations. The system size dependence of Binders cumulant, specific heat, order parameter and finite size scaling of order parameter universally suggest the existence of a phase transition. The absence of hysteresis and Scaling of Binders energy cumulant minimum confirm the continuous nature of the transition. The finite size scaling analyses give rise to the mean field nature of the transition. Plausible applications of the proposed model in modeling dipolar liquids in confined systems are also discussed. In Appendix A, we discuss a preliminary study of front propagation in a non-equilibrium system. The model system analogous to the super cooled liquid shows non-Avrami domain growth during rejuvenation. The origin of the non-Avrami nature of the domain growth and the presence of cross over are also discussed. In Appendix B, we discuss umbrella a sampling technique and WHAM analysis which is used in ChapterIII.2 to get the free energy of polydisperse LJ system.

L’objectif de cette thèse était de mettre au point une analyse critique de vecteurs polymères utilisés pour la thérapie photodynamique (PDT) et de faire le lien avec l’efficacité thérapeutique observée. Pour cela, une analyse complète des vecteurs a été réalisée par des techniques classiques comme la diffusion dynamique de la lumière ou la microscopie électronique, mais aussi grâce au fractionnement flux-force, technique peu utilisée jusqu’à présent dans le domaine des auto-assemblages polymères. Dans un deuxième temps, les auto-assemblages ont été utilisés comme vecteurs d’un photosensibilisateur, le Phéophorbide a, et l’efficacité thérapeutique évaluée en travaillant sur culture cellulaire 2D et 3D de lignées HCT116 (cancer du colon) ou FaDu (cancer tête et cou). Différents vecteurs polymères simples ont tout d’abord été examinés, à savoir des micelles ou des polymersomes à base de copolymères diblocs amphiphiles comme le poly(oxyde d’éthylène-b--caprolactone), le poly(oxyde d’éthylène-b-lactide) ou le poly(oxyde d’éthylène-b-styrène). Ceci a permis d’obtenir des vecteurs présentant des tailles et des morphologies variables. Les résultats en PDT ont montré des comportements différents et une meilleure efficacité en 3D pour les systèmes à base de PEO-PDLLA. La technique de fractionnement flux-force asymétrique (AsFlFFF) a particulièrement été utilisée pour ces vecteurs afin de démontrer la pureté des auto-assemblages. Les connaissances acquises dans cette première partie ont permis de caractériser des vecteurs faits à base de mélanges d’auto-assemblages micelles/vésicules. Ceux-ci ont révélé des phénomènes d’antagonisme ou de synergie dans l’efficacité en PDT, démontrant l’existence de processus complexes au niveau de la réponse cellulaire.Des auto-assemblages figés par réticulation ont aussi été développés, caractérisés et examinés en PDT. Ils se sont avérés extrêmement intéressants pour la PDT sur les cultures cellulaires en 3D, démontrant une efficacité accrue comparée aux systèmes simples. La comparaison de ces résultats avec ceux obtenus en culture 2D pour les mêmes objets a de plus permis de mettre en évidence la différence entre ces deux modèles biologiques. Enfin, des auto-assemblages à base de complexes poly-ioniques ont aussi été formés et caractérisés. Le fractionnement flux-force s’est là encore avéré efficace, mais a nécessité l’utilisation d’une injection spéciale par Frit-inlet. Leur efficacité en PDT s’est avérée faible. / The objective of this study was to critically analyze different polymer self-assemblies used for photodynamic therapy (PDT) and to link this analysis to their therapeutic efficiency. To do that, a thorough characterization of the vectors has been performed by classical techniques such as Dynamic Light Scattering or electron Microscopy, but also using flow fractionation, which has been seldomly used so far for polymeric self-assemblies. In a second step, these have been used as vectors of a photosensitizer, namely Phéophorbide a, and the therapeutic efficiency assessed on both 2D and 3D cell cultures of HCT 116 (colon cancer) and FaDu (head and neck cancer) cells. Different simple polymer vectors have first been evaluated, namely micelles and polymersomes based on diblock amphiphilic copolymers such as poly(ethylene-oxide-b--caprolactone), poly(ethylene-oxide-b-lactide) or poly(ethylene-oxide-b-styrene). This enabled obtaining vectors exhibiting various sizes and morphologies. Results in PDT showed different behaviours and a better efficiency in 3D for PEO-PDLLA. The Asymmetric Flow Field Flow Fractionation was particularly used for these systems to demonstrate their purity. The acquired expertise on this part enabled us to also characterize vectors made of known mixtures of micelles and polymersomes. These revealed antagonism and synergy effects in PDT, demonstrating the presence of complex processes for the cell response. Other self-assemblies consisting of crosslinked systems have also been developed and characterized. These were observed to be particularly efficient for PDT on 3D cell cultures. The comparison of these results with those for the 2D cell culture enabled to highlight the difference between those two biological systems. Finally, self-assemblies based on Polyion Complexes were also formed and characterized. Field Flow Fractionation was once again used as a powerful technique for this, although this implied the use of a special injection device called Frit Inlet. Their PDT efficiency however proved to be low.

Des poly(liquides ioniques) (PILs) arrangés sous la forme de copolymères statistiques,de nanoparticules à chaine unique ou bien sous la forme de copolymères à blocs autoassemblés ont été employés comme précurseurs de carbènes N-hétérocycliques (NHC)s à des fins de catalyses organiques ou organométalliques. L’introduction d’anions acétate dans des unités PIL dérivés d’imidazolium permet la génération in situ de NHCs actifs en catalyse. Les nanoparticules composées d’une chaine unique polymère repliée sur elle-même (SCNP) ont été spécialement conçues selon deux stratégies impliquant, d’une part, une réaction d’autoquaternisation entre groupements fonctionnels antagonistes portés par la chaine et, d’autre part, une réaction de complexation organométallique à l’aide d’un sel de palladium. Dans lesdeux cas, les chaines polymères ont été obtenues par polymérisation contrôlée (méthode RAFT). Les copolymères à blocs amphiphiles comportant un bloc PIL fonctionnalisé par du palladium ont été synthétisés par polymérisation RAFT et auto-assemblés dans l’eau sous forme de micelles.Un effet de confinement des sites catalytiques a clairement été démontré à travers des réactions de catalyse pour les couplages de Suzuki et de Heck dans l’eau, avec un gain cinétique très net par rapport à des homologues non micellisés, en plus d’une grande facilité de recyclage de ces supports micellaires.Enfin, des copolymères à blocs à base de PIL-benzimidazolium à contre anion bis(trifluoromethane)-sulfonylimide de lithium ont été développés comme agents dopants conducteurs ioniques de matrices structurantes PS-b-PEO. Des mélanges configurés en films minces avec une quantité minimale d’agent dopant ont conduit dans certaines conditions à des valeurs optimales de conductivité ionique grâce à une nano structuration des films à longue distance. / Poly(ionic liquid)s (PILs) in the form of random copolymers, single chain nanoparticles(SCNPs), or self assembled block copolymers have been used as N-heterocyclic carbenes(NHCs) precursors for the purpose of organic and organometallic catalysis. Introducing acetate derivative counter anion in imidazolium based PIL units enable in situ generation of catalyticallyactive NHC. SCNPs have been specially designed along two strategies including, firstly, a self quaternization reaction involving two antagonists groups supported on to the polymer chain and,secondly, an organometallic complexation featuring palladium salt. Both polymeric precursors were obtained using RAFT as controlled polymerization method. Amphiphilic block copolymers composed of a PIL block functionalized by palladium have been synthesized by RAFT and self-assembled in water, leading to micellar structures. Confinement effect has been demonstrated through Suzuki and Heck coupling in water showing kinetic gain compared to molecular homologue in addition to an easier recycling method.Finally, PIL-benzimidazolium based block copolymers with lithium bis(trifluoromethane)-sulfonylimide anion have been developed as ionic conductor doping agent for PS-PEO matrix. Thin films blends with minimum doping agent amount led to optimum ionic conductivity owing tolong range order.

<p>Uvod: U pro&scaron;losti žučne kiseline su uglavnom razmatrane sa stanovi&scaron;ta njihove funkcije koju obavljaju u crevima jer posreduju u varenju masti i apsorpciji liposolubilnih vitamina. Nedavne studije potvrđuju da žučne kiseline ne igraju samo ulogu u varenju masti, nego se pona&scaron;aju i kao signalni molekuli koji stupaju u interakciju sa raznim receptorima uključujući nuklearne receptore i receptore vezane za G-proteine. Kao amfipatični molekuli one su sposobne da reaguju sa fosfolipidima ćelijskih membrana i da pobolj&scaron;avaju prolazak lekova kroz njih. Stoga se žučne kiseline razmatraju kao promoteri u bukalnim, okularnim i nazalnim farmaceutskim formulacijama. Cilj: Svrha ovog istraživanja je bila da se ispitaju žučne kiseline i njihovi okso derivati kao jedinjenja koja utiču na propustljivost ćelijskih membrana i prolazak lekova do ciljnih tkiva. Materijal i metod: Interakcije makrolidnih antibiotika i žučnih kiselina su ispitivane uz pomoć NMR difuzionih merenja i relaksacije paramagnetičnim jonima. Retencioni parametri odabranih žučnih kiselina su dobijeni kori&scaron;ćenjem hromatografije na normalnim fazama i evaluisani su primenom pet različitih softvera. In vivo ekaperimenti su sprovedeni na 126 eksperimentalnih životinja koje su bile podeljene u 21 grupu. Rezultati: Vezivanje žučnih kiselina za micele je indikovano razlikama u hemijskom pomeranju makrolida i pro&scaron;irenju signala kao posledica redukovane mobilnosti unutar micela. Dodatak micela žučnih kiselina povećava solubilizaciju makrolida za faktor približno 2-3. Sprovedena korelaciona analiza pokazala je značajnu zavisnost između faktora retencije i intestinalne apsorpcije, prodora u MDCK epitelne ćelije, permeabilnost kroz kožu, logBB i PPB%. Putem implementacije in vivo eksperimentalnog dela pokazano je da žučne kiseline utiču na prolazak makrolida u tkivo mozga, bubrega i jetre. Zaključak: Ispitivane žučne kiseline pokazuju dobre farmakokinetske karakteristike i olak&scaron;avaju prolazak makrolida kroz različite ćelijske membrane.</p> / <p>Introduction: In the past, bile acids were mostly considered to function in the intestine where they play a role in digestion of fats and mediate absorption of fat-soluble vitamins. Recent studies confirm that bile acids not only facilitate solubilization of fats but behave as signal molecules that interact with various receptors including nuclear receptors and G protein-coupled receptors. As amphipathic molecules they are able to interact with phospholipids of cells membranes and enhance drugs permeation. Thus, bile acids are considered as drug promoters in buccal, ocular, nasal, and transdermal dosage forms. Purpose: The purpose of this research was to investigate bile acids and its oxo derivatives as enhancers in drug permeability. Three research methods to evaluate the characteristics of bile acids and its properties were used. Material and method: The interaction between macrolide antibiotics and bile acids was investigated by NMR chemical-shift titration, self-diffusion measurements and paramagnetic relaxation enhancements. Retention parameters of selected bile acids are acquired by normal-phase thin layer chromatography and evaluated using five different softwares. In vivo experiments were conducted on 126 animals which were divided in 21 groups. Results: Binding bile acids to the micelles is indicated by differences in the chemical shift of the macrolides and line broadening as a consequence of reduced mobility in the micelle. Addition of bile micelles increases the solubility of macrolide antibiotics by a factor of approximately 2&ndash;3. Examined correlation analysis confirmed significant dependence between retention factor and intestinal absorption, MDCK epithelial cells, skin permeability, logBB and PPB%. Through the implementation of in vivo experiments it is shown that bile acids promote penetration of macrolides in brain tissue, kidney and liver. Conclusion: Investigated bile acids showed good pharmacokinetic properties and facilitate in macrolides permeation through various membranes.</p>

Les copolymères poly (acétate de vinyle-co-alcool vinylique), désignés par PVA, sont des tensioactifs macromoléculaires obtenus par hydrolyse partielle de poly (acétate de vinyle)(PVAc). Si les propriétés tensioactives des PVA ont pu être corrélées aux caractéristiques moléculaires il n'en est par de même en ce qui concerne les associats du type nanogels présents dans les solutions aqueuses. L'objectif de cette thèse était de caractériser les nanogels par des techniques telles que la diffusion dynamique de la lumière, la chromatographie d'exclusion stérique et la viscosimétrie. 9 PVA, de degrés d'hydrolyse de 73 à 88 mole% et de degrés de polymérisation de 650 à 2500 ont été étudiés. Il est apparu que les nanogels présent dans les PVA de DH =73 mole% et formés par interactions hydrophobe-hydrophobe entre séquences acétate ont des tailles entre 20-40 nm, avec des fractions volumiques de l'ordre de 20-30%. La désagrégation des nanogels par formation de complexes avec des tensioactifs anioniques du type SDS et SDBS a ensuite été démontrée. En faisant appel à la technique de fractionnement par « point de trouble » il est apparu que les chaînes les plus riches en acétate et en particulier celles ayant des longueurs des séquences acétate importantes complexent plus de SDS.Des « copolymères modèles » du type copolymères diblocs PVAc-b-PVOH comportant une séquence hydrophobe PVAc et une hydrophile PVOH ont pu être préparés par polymérisation RAFT, suivie par une réaction click. Une étude préliminaire de la micellisation de tels copolymères a permis de montrer la très grande analogie entre micelles de copolymères à blocs PVAc-b-PVOH et les nanogels de PVA examinés précédemment. / Poly (vinyl acetate-co-vinyl alcohol) copolymers, designated by PVA, are macromolecular surfactants obtained by partial hydrolysis of poly (vinyl acetate) (PVAc). If the surfactant properties of PVA have been correlated with molecular characteristics it is not the same for the colloidal aggregates in aqueous solutions so-called nanogels. The objective of this thesis was to characterize the nanogels using techniques such as dynamic light scattering, size exclusion chromatography and viscometry.9 PVA with degrees of hydrolysis between 73 and 88 mole% and polymerization degrees of 650 to 2500 were studied. It appeared that the nanogels, formed by hydrophobic-hydrophobic interactions between acetate sequences, are the size in the range of 20 to 40 nm with volume fractions between 20 and 30%. The disaggregation of nanogels by complex formation with anionic surfactants such as SDS and SDBS was further demonstrated. By using the "cloud point" fractionation technique it appeared that SDS is complexed by the sequences with high acetate content and in particular those with significant lengths of acetate sequences.As a model system diblock copolymers PVAc-b-PVOH containing a PVAc hydrophobie sequence and a PVOH hydrophilic sequence were prepared by RAFT polymerization, followed by a click reaction. A preliminary micellization study of these copolymers showed a very strong analogy between PVAc-b-PVOH block copolymer micelles and PVA nanogels discussed above.

A própolis verde brasileira é um dos produtos de abelha mais consumidos no mundo devido às suas atividades antioxidantes, antiinflamatórias, antimicrobianas e antitumorais. Coletada pela espécie Apis mellifera, esta própolis possui a maior porcentagem de Artepilina C dentre as demais própolis. A molécula, derivada do ácido cinâmico, possui dois grupos prenilados, o que favorece a afinidade do composto pelo ambiente lipofílico. Um grupo carboxila também está presente na estrutura da Artepilina C, tornando-a um composto sensível ao pH, o que pode modular sua atividade biológica relacionada a interações com a membrana celular de organismos e tecidos. Neste trabalho investigamos as propriedades da Artepilina C em solução aquosa e interações entre Artepilina C e agregados anfifílicos comumente usados como modelos de membranas, ou seja, micelas e vesículas unilamelares, usando absorção óptica e espectroscopias de fluorescência em estado estacionário e resolvida no tempo. O grupo carboxila pode estar tanto na forma protonada quanto na forma desprotonada, mostrando equilíbrio em pH 4,65. Em pH abaixo do valor de pKa, uma banda de absorção aumentou em torno de 350 nm em concentração de Artepillin C acima de 50 M devido à agregação da molécula. Em pH neutro, com excitação a 310 nm, a Artepilina C apresenta dupla emissão a 400 e 450 nm, onde a segunda pode estar relacionada com diferentes interações entre as formas isoméricas da molécula. O tempo de vida fluorescente foi ajustado por uma função triexponencial, dominada por uma componente muito curta, em torno de 60 ps. Desta forma, a emissão fluorescente ocorreu antes da despolarização, resultando em valores muito altos de anisotropia de fluorescência. A interação da Artepilina C e membranas modelo foi estudada com micelas aniônicas, catiônicas e zwitteriônicas (respectivamente SDS, CTAB e HPS) e com vesículas unilamelares grandes de DMPC, DMPG e DODAB. Devido às cargas na superfície das micelas e das vesículas, o pH local é diferente do meio (bulk) e os espectros de absorção óptica mostraram que o estado de protonação do composto depende deste pH local. A polaridade em torno da Artepilina C diminuiu na presença de micelas e vesículas de acordo com os espectros de emissão de fluorescência, levando-nos a acreditar que a molécula está localizada na interface água/lipídio. A carga negativa do composto em estado desprotonado favorece a interação com micelas catiônicas e vesículas neutras. Os efeitos são mais proeminentes quando vesícula lipídica está na fase fluida. / Brazilian green propolis is one of the most consumed bee product in the world because of its known antioxidant, anti-inflammatory, antimicrobial and antitumor activities. Collected by the species Apis mellifera, this propolis has the major percentage of Artepillin C among others worldwide propolis. The molecule, derived of cinnamic acid, has two prenylated groups, which improves the affinity of the compound for lipophilic environment. A carboxylic group is also present in the Artepillin C structure, making it a pH-sensitive compound, what may modulate its biological activity related to interactions with the cellular membrane of organisms and tissues. In this work we investigated the properties of Artepillin C on aqueous solution and interactions between Artepillin C and amphiphilic aggregates commonly used as membrane models, namely, micelles and unilamellar vesicles, using optical absorption, steady state and time-resolved fluorescence spectroscopies. The carboxyl group may be either in protonated or deprotonated form, showing equilibrium at pH 4,65. In pH below the pKa value, an absorption band raised around 350 nm at Artepillin C concentration above 50 M, due to aggregation of the molecule. In neutral pH, with excitation at 310 nm, Artepillin C presents dual emission at 400 and 450 nm, where the second one could be related with different interactions between isomeric forms of the molecule. The fluorescent lifetime is a three-exponential function dominated by a very short component, around 60 ps. Therefore, the emission occurred before fluorescence depolarization, resulting in very high values of fluorescence anisotropy. The interaction of Artepillin C and membrane models was studied with anionic, cationic and zwitterionic (respectively SDS, CTAB and HPS) micelles, and with large unilamellar vesicles of DMPC, DMPG and DODAB. Due to the charges in micelles and in vesicles surfaces, the local pH was different from the bulk and the optical absorption spectra showed that the protonation state of the compound depends on this pH. The polarity around Artepillin C decreased in the presence of micelles and vesicles according to fluorescence emission spectra, leading us to believe that the molecule should be located at the water/lipid interface. The negative charge of the compound in deprotonated state favors the interaction with cationic micelles and neutral vesicles. The effects are more prominent when the lipid vesicles are in the fluid phase

A própolis verde brasileira é um dos produtos de abelha mais consumidos no mundo devido às suas atividades antioxidantes, antiinflamatórias, antimicrobianas e antitumorais. Coletada pela espécie Apis mellifera, esta própolis possui a maior porcentagem de Artepilina C dentre as demais própolis. A molécula, derivada do ácido cinâmico, possui dois grupos prenilados, o que favorece a afinidade do composto pelo ambiente lipofílico. Um grupo carboxila também está presente na estrutura da Artepilina C, tornando-a um composto sensível ao pH, o que pode modular sua atividade biológica relacionada a interações com a membrana celular de organismos e tecidos. Neste trabalho investigamos as propriedades da Artepilina C em solução aquosa e interações entre Artepilina C e agregados anfifílicos comumente usados como modelos de membranas, ou seja, micelas e vesículas unilamelares, usando absorção óptica e espectroscopias de fluorescência em estado estacionário e resolvida no tempo. O grupo carboxila pode estar tanto na forma protonada quanto na forma desprotonada, mostrando equilíbrio em pH 4,65. Em pH abaixo do valor de pKa, uma banda de absorção aumentou em torno de 350 nm em concentração de Artepillin C acima de 50 M devido à agregação da molécula. Em pH neutro, com excitação a 310 nm, a Artepilina C apresenta dupla emissão a 400 e 450 nm, onde a segunda pode estar relacionada com diferentes interações entre as formas isoméricas da molécula. O tempo de vida fluorescente foi ajustado por uma função triexponencial, dominada por uma componente muito curta, em torno de 60 ps. Desta forma, a emissão fluorescente ocorreu antes da despolarização, resultando em valores muito altos de anisotropia de fluorescência. A interação da Artepilina C e membranas modelo foi estudada com micelas aniônicas, catiônicas e zwitteriônicas (respectivamente SDS, CTAB e HPS) e com vesículas unilamelares grandes de DMPC, DMPG e DODAB. Devido às cargas na superfície das micelas e das vesículas, o pH local é diferente do meio (bulk) e os espectros de absorção óptica mostraram que o estado de protonação do composto depende deste pH local. A polaridade em torno da Artepilina C diminuiu na presença de micelas e vesículas de acordo com os espectros de emissão de fluorescência, levando-nos a acreditar que a molécula está localizada na interface água/lipídio. A carga negativa do composto em estado desprotonado favorece a interação com micelas catiônicas e vesículas neutras. Os efeitos são mais proeminentes quando vesícula lipídica está na fase fluida. / Brazilian green propolis is one of the most consumed bee product in the world because of its known antioxidant, anti-inflammatory, antimicrobial and antitumor activities. Collected by the species Apis mellifera, this propolis has the major percentage of Artepillin C among others worldwide propolis. The molecule, derived of cinnamic acid, has two prenylated groups, which improves the affinity of the compound for lipophilic environment. A carboxylic group is also present in the Artepillin C structure, making it a pH-sensitive compound, what may modulate its biological activity related to interactions with the cellular membrane of organisms and tissues. In this work we investigated the properties of Artepillin C on aqueous solution and interactions between Artepillin C and amphiphilic aggregates commonly used as membrane models, namely, micelles and unilamellar vesicles, using optical absorption, steady state and time-resolved fluorescence spectroscopies. The carboxyl group may be either in protonated or deprotonated form, showing equilibrium at pH 4,65. In pH below the pKa value, an absorption band raised around 350 nm at Artepillin C concentration above 50 M, due to aggregation of the molecule. In neutral pH, with excitation at 310 nm, Artepillin C presents dual emission at 400 and 450 nm, where the second one could be related with different interactions between isomeric forms of the molecule. The fluorescent lifetime is a three-exponential function dominated by a very short component, around 60 ps. Therefore, the emission occurred before fluorescence depolarization, resulting in very high values of fluorescence anisotropy. The interaction of Artepillin C and membrane models was studied with anionic, cationic and zwitterionic (respectively SDS, CTAB and HPS) micelles, and with large unilamellar vesicles of DMPC, DMPG and DODAB. Due to the charges in micelles and in vesicles surfaces, the local pH was different from the bulk and the optical absorption spectra showed that the protonation state of the compound depends on this pH. The polarity around Artepillin C decreased in the presence of micelles and vesicles according to fluorescence emission spectra, leading us to believe that the molecule should be located at the water/lipid interface. The negative charge of the compound in deprotonated state favors the interaction with cationic micelles and neutral vesicles. The effects are more prominent when the lipid vesicles are in the fluid phase

Made available in DSpace on 2014-12-17T15:42:14Z (GMT). No. of bitstreams: 1 GuymmannCS_DISSERT-.pdf: 2904070 bytes, checksum: 4cd1c00978977c422c79766db70f2678 (MD5) Previous issue date: 2011-08-12 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior / Alkyl polyethoxylates are surfactants widely used in vastly different fields, from oil exploitation to pharmaceutical applications. One of the most interesting characteristics of these surfactants is their ability to form micellar systems with specific geometry, the so-called wormlike micelle. In this work, microemulsions with three distinct compositions (C/T = 40 %, 30 % and 25 %) was used with contain UNITOL / butanol / water / xylene, cosurfactant / surfactante (C/S) ratio equal to 0,5. The microemulsion was characterized by dynamic light scattering (DLS), capillary viscometry, torque rheometry and surface tensiometry experiments carried out with systems based on xylene, water, butanol (cosurfactant) and nonaethyleneglycolmonododecyl ether (surfactant), with fixed surfactant:cosurfactant:oil composition (with and without oil phase) and varying the overall concentration of the microemulsion. The results showed that a transition from wormlike micelles to nanodrops was characterized by maximum relative viscosity (depending on how relative viscosity was defined), which was connected to maximum effective diameter, determined by DLS. Surface tension suggested that adsorption at the air water interface had a Langmuir character and that the limiting value of the surfactant surface excess was independent of the presence of cosurfactant and xylene. The results of the solubilization of oil sludge and oil recovery with the microemulsion: C/S = 40%, 30% and 25% proved to be quite effective in solubilization of oil sludge, with the percentage of solubilization (%solubilization) as high as 92.37% and enhanced oil recovery rates up to 90.22% for the point with the highest concentration of active material (surfactant), that is, 40%. / Os tensoativos alquil-polietoxilados s?o amplamente utilizados em diferentes campos, desde a explota??o de petr?leo at? aplica??es na ind?stria farmac?utica. Uma das caracter?sticas mais interessantes destes tensoativos ? a sua capacidade de formar sistemas micelares que apresentam uma geometria micelar espec?fica, a chamada micela wormlike, tipo verme . Neste trabalho, foram utilizados tr?s pontos de microemuls?o: C/T = 40 %, C/T = 30 % e C/T = 25 % num sistema contendo UNITOL/xileno/butanol/?gua. Esses pontos de microemuls?o foram caracterizados por espalhamento de luz din?mico (DLS), viscosimetria capilar, reometria de torque e tens?o superficial com composi??es de tensoativo, cotensoativo e ?leo fixo - 5 % (com e sem fase ?leo) e variando a concentra??o total dos pontos de microemuls?o. Os resultados mostraram que a transi??o da geometria de micela wormlike para nanogotas poderia ser caracterizada por um m?ximo na viscosidade relativa (dependendo de como a viscosidade foi definida), que foi vinculado a um m?ximo de di?metro efetivo, determinada por DLS. A tens?o superficial sugeriu que a adsor??o na interface ?gua/ar tinha um car?ter de Langmuir, o limite de excesso da superf?cie do tensoativo ? independente da presen?a de cotensoativo e do xileno, e que o valor limite do excesso superficial foi independente da presen?a de cotensoativo e xileno. Os resultados da solubiliza??o da borra de petr?leo e da recupera??o avan?ada de petr?leo com os pontos de microemuls?o C/T = 40 %, C/T = 30 % e C/T = 25 %, se mostraram bastante eficaz com solubiliza??o da borra de petr?leo, com porcentagem de solubiliza??o (% solubiliza??o) at? 92,37 %, e recupera??o avan?ada de petr?leo de at? 90,22 % para o ponto que apresenta maior concentra??o de mat?ria ativa (tensoativo), ou seja, C/T = 40 %.