Les liposomes sont des nanovecteurs polyvalents et prometteurs quant à leur utilisation dans plusieurs domaines. Il y a une décennie, un nouveau type de liposome constitué d’amphiphiles monoalkylés et de stérols est né fortuitement dans notre groupe. Ils sont nommés Stérosomes puisqu’ils contiennent une grande proportion de stérols, entre 50 et 70 mol %. Les objectifs de cette thèse sont de développer de nouvelles formulations de Stérosomes ayant des caractéristiques spécifiques et d’acquérir une compréhension plus profonde des règles physicochimiques qui dictent leur comportement de phase. Nous avons spécifiquement examiné le rôle de motifs moléculaires des stérols, de la charge interfaciale et de la capacité à former des liaisons H dans les interactions intermoléculaires menant à l’autoassemblage. Le comportement de phase a été caractérisé par calorimétrie différentielle à balayage (DSC), par spectroscopie infrarouge (IR) et par spectroscopie de résonance magnétique nucléaire du deutérium (²H NMR). Premièrement, nous avons établi certaines corrélations entre la structure des stérols, leur tendance à former des bicouches fluides en présence d'amphiphile monoalkylé et la perméabilité des grandes vésicules unilamellaires (LUV) formées. La nature des stérols module les propriétés de mélange avec de l’acide palmitique (PA). Les stérols portant une chaîne volumineuse en position C17 sont moins aptes à induire des bicouches fluides que ceux qui ont une chaîne plus simple, comme celle du cholestérol. Un grand ordre de la chaîne alkyle de PA est un effet commun à tous les stérols investigués. Il a été démontré que la perméabilité des LUV peut être contrôlée en utilisant des stérols différents. Cependant, ces stérols n’ont aucun impact significatif sur la sensibilité des Stérosomes au pH. Afin de créer des liposomes qui sont sensibles au pH et qui ont une charge positive à la surface, des Stérosomes composés de stéarylamine et de cholestérol (Chol) ont été conçus et caractérisés. Il a été conclu que l’état de protonation de l’amine, dans ce travail, ou du groupe carboxylique, dans un travail précédent, confère une sensibilité au pH et détermine la charge à la surface du liposome. Les premiers Stérosomes complètement neutres ont été fabriqués en utilisant un réseau de fortes liaisons H intermoléculaires. Le groupe sulfoxyde est capable de former de fortes liaisons H avec le cholestérol et les molécules d’eau. Une bicouche fluide métastable a été obtenue, à la température de la pièce, à partir d'un mélange équimolaire d’octadécyl méthyl sulfoxyde (OMSO) et de Chol. Ce comportement distinct a permis d’extruder le mélange pour former des LUV à la température de la pièce. Après 30 h, le temps de vie de la phase métastable, des Stérosomes stables et imperméables existaient toujours sous une forme solide. Un diagramme de température-composition a été proposé afin de résumer le comportement de phase des mélanges d’OMSO/Chol. Finalement, nous avons élaboré des Stérosomes furtifs en incorporant du polyéthylène glycol (PEG) avec une ancre de cholestérol (PEG-Chol) à l’interface de Stérosomes de PA/Chol. Jusqu’à 20 mol % de PEG-Chol peut être introduit sans perturber la structure de la bicouche. La présence du PEG-Chol n’a aucun impact significatif sur la perméabilité de la LUV. L'encapsulation active de la doxorubicine, un médicament contre le cancer, a été réalisée malgré la faible perméabilité de ces LUV et la présence du PEG à l’interface. L’inclusion de PEG a modifié considérablement les propriétés de l’interface et a diminué la libération induite par la variation de pH observée avec des LUV nues de PA/Chol. Cette formulation inédite est potentiellement utile pour l’administration intraveineuse de médicaments. / Liposomes are promising and versatile nanocarriers suitable for potential applications in many fields. A decade ago, a new type of liposomes formed from monoalkylated amphiphiles and sterols was born somehow fortuitously in our group. They are referred to as Sterosomes, because they contain a large proportion of sterols, between 50 and 70 mol %. The objectives of the present thesis are to develop novel Sterosome formulations with specific features, and to gain a deeper understanding of the physicochemical rules that dictate their phase behavior. We have specifically examined the role of the molecular features of sterols, of the interfacial charges and of the H-bond capacity in the intermolecular interactions leading to the self-assembly. The phase behavior was characterized by differential scanning calorimetry (DSC), infrared spectroscopy (IR), and nuclear magnetic resonance spectroscopy of deuterium (2H NMR). First, we have established some correlations between the structure of the sterols, the propensity to form fluid bilayers, and the permeability of the resulting large unilamellar vesicles (LUVs). The nature of the sterol modulates the properties of the mixture with palmitic acid (PA). Sterols bearing a bulky tail chain at C17 are less capable to induce fluid bilayers than those with a non-bulky tail chain, like that of cholesterol. A large ordering of the alkyl chain of PA is an effect exhibited by all of the investigated sterols. It is shown that the permeability of the LUVs can be controlled using different sterols. However, these sterols have no significant impact on the pH-sensitivity of Sterosomes. In order to create liposomes that are pH-sensitive and that have a positive surface charge, Sterosomes composed of stearylamine and cholesterol (Chol) were designed and characterized. It is concluded that the protonation/deprotonation state of the amine (in this work) and carboxylic acid (in previous work) groups confers the pH-sensitivity and determines the surface charge of the liposomes. The first completely neutral Sterosomes were crafted based on the creation of strong intermolecular hydrogen bond networks. The sulfoxide group was capable of forming strong hydrogen bonds with cholesterol and water molecules. In an equimolar octadecyl methyl sulfoxide (OMSO)/Chol mixture, a metastable fluid bilayer was obtained at room temperature. This distinct phase behavior allowed extruding the mixtures to form LUVs at room temperature. After 30 h, the life-time of the metastable phase, stable and impermeable Sterosomes still existed in the solid form. A temperature–composition diagram was proposed to summarize the phase behavior of OMSO/Chol mixtures. Finally, a further step was made to prepare “stealth” Sterosomes by incorporating polyethylene glycol (PEG) with a cholesterol anchor (PEG-Chol) at the interface of PA/Chol Sterosomes. Up to 20 mol % PEG-Chol can be introduced without disturbing the bilayer structure. The presence of PEG-Chol had no significant impact on the permeability of the resulting LUVs. Active-loading of an anti-cancer drug, doxorubicin, can be achieved despite the low permeability of these LUVs and the presence of the PEG at the interface. The inclusion of PEG modified considerably the interface properties and decreased significantly the pH-triggered release observed with naked PA/Chol LUVs. This novel formulation is potentially useful for the application of intravenous administration in the drug delivery field.

Ce travail a été mené afin d’étudier l’effet du FGF 2 et du TGF-β1 sur les étapes précoces de la régénération dentinaire en utilisant la micro-encapsulation de ces facteurs dans une matrice pour les protéger et contrôler leur libération et ensuite l’application des microparticules obtenues en coiffage pulpaire direct dans un modèle de culture de dents entières. Ce travail consiste d’abord à l’optimisation des moyens techniques mis en oeuvre pour réaliser l'encapsulation du TGFβ1, FGF-2 à l'aide de l'acide poly (lactique-glycolique) PLGA. Les études de la caractérisation colloïdal et physico chimique des microparticules montre que les microparticules gardent leurs caractéristiques physicochimiques après séchage et resuspension dans l’eau. La procèdes optimisé a été ensuite utilisé pour encapsuler les facteurs de croissance. L’encapsulation de FGF-2 et TGF-β1 a été obtenue avec une taille, une efficacité d’encapsulation et une profile de libération adaptés au type d’application choisi. Les études biologiques ne montrent aucun effet toxique des particules sur les fibroblastes pulpaires. Les facteurs de croissance ont gardé leur activité biologique spécifique. Un modèle de culture de dent entier humain a été utilisé pour réaliser l’application de nos microparticules comme un matériau de coiffage dentaire pour confirmer leurs activités biologiques ex-vivo. Ces microparticules peuvent être utiles dans les études des étapes précoces de la régénération dentinaire, l'activation et la migration des cellules progénitrices de la pulpe dentaire / The purpose of this work was to investigate the effect of FGF 2 and TGF-β1 on the early steps of dentin regeneration using microencapsulation of theses factors into a microparticles matrix to ensure growth factors protection and to provide bioactive sustained release in contact with dental pulp cells and then the application of the obtained microparticles in direct pulp capping using a culture model of entire tooth. This work involves the optimization of technical means used to achieve encapsulation of TGFβ1, FGF-2 using the poly (lactic-glycolic acid) PLGA. Physicochemical and colloidal characterization of microspheres shows that the microparticles retain their physicochemical characteristics after drying and re-suspended in water. The double emulsion method was used to separately encapsulate (FGF-2) and (TGFβ1). Microparticles morphology, loading, shelf life, potential toxicity and release kinetics were studied. Then the proliferation of dental pulp cells was examined in contact with microparticles. Biological studies show no toxic effect of particles on pulp fibroblasts. Growth factors have kept their specific biological activity. A culture model of human entire tooth was used to achieve the application of microparticles as a dental direct capping material to confirm their biological activities ex vivo. These microparticles can be useful in studies of early steps of dentin regeneration, activation and migration of progenitor cells in dental pulp

L’auto-assemblage de copolymères à blocs amphiphiles est un outil puissant de la chimie supramoléculaire pour la conception de nano-objets complexes et fonctionnels. Dans ces travaux de thèse, l’étude approfondie d’un copolymère à blocs « hybride » synthétique-b-peptidique poly(triméthylène carbonate)-b-poly(acide glutamique) pour des applications de vectorisation a été menée. Des morphologies vésiculaires, obtenues par auto-assemblage en voie « co-solvant » et présentant une grande stabilité ainsi qu’un caractère stimulable ont été mises en évidence. Une transition inédite en température, par des phénomènes de fusion et de fission, a pu être observée. L’encapsulation dans ces vésicules polymères d’un principe actif anti-tumoral et de nanoparticules magnétiques, à des taux très élevés, permet d’améliorer le contraste en IRM ainsi que de moduler la libération de la molécule par une variation des paramètres environnementaux (pH, T) ou par un effet d’hyperthermie magnétique. / Block copolymer self-assembly is a powerful tool within supramolecular chemistry to design smart and functional nano-objects. In this thesis work, comprehensive study of hybrid poly(trimethylene carbonate)-b-poly(glutamic acid) block copolymers for drug delivery applications has been conducted. Highly stable vesicular morphologies presenting stimuli-responsive behaviour were prepared using a solvent-injection method. In particular, original temperature responsiveness mediated by fusion and fission events has been evidenced. Dual loading of an anticancer drug and superparamagnetic nanoparticles in these vesicles, at very high loading contents, allows enhancing MRI contrast and controlling drug release kinetics by varying environmental conditions (pH, T) or by using a magnetic hyperthermia effect.

Made available in DSpace on 2017-07-21T14:13:10Z (GMT). No. of bitstreams: 1 Fernanda Malaquias Barbosa.pdf: 3020021 bytes, checksum: d88917643a806ad362e493cbc6e1776b (MD5) Previous issue date: 2013-02-21 / Manidipine is a third-generation calcium channel blocking effective in the treatment of hypertension, which its use has been related to further metabolic effects of potential clinical interest. However, its high lipophilicity results in undesirable physicochemical and biopharmaceutical properties. Thus, a pharmaceutical improvement is necessary to achieve a remarkable advance in its absorption and bioavailability. In that sense, the aim of this paper was to microencapsulate the manidipine in order to avoid its spontaneous compartmentalization in adipocytes and make its intestinal transit longer, with appropriate release rates and duration to generate the desired antihypertensive effect. Poly(ε-caprolactone) (PCL) and poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) microparticles containing manidipine were successfully prepared by simple emulsion/solvent evaporation method. Considering the lack of validated methods for drug quantification in these microparticles, an analytical method by high efficiency liquid chromatography with spectrometric detection in the ultraviolet region was previously developed and validated. This method proved to be selective, linear (r = 0.9992), precise (RSD < 2.08 %) and accurate (recovery capacity between 95.02 and 100.41%) in the range from 10 to 50 μg.mL-1. The chromatography was robust when underwent slight variations in the mobile phase composition and column temperature. All four formulations showed loading efficiency rates greater than 80% and average particle sizes less than 8 μm. Microparticulate systems showed a spherical shape with smooth and porous surface for PCL and PHBV formulations, respectively. According to Fourier-transformed infrared analysis, initial components were not chemically modified during microencapsulation process, whereas X-ray diffraction patterns and differential scanning calorimetry analysis demonstrated that this process led to drug amorphization. In vitro dissolution profile showed that all microparticles prepared were able to sustain manidipine release, especially which one prepared from PCL, that contained 5% of the drug loaded (PCL-M5). Animal studies demonstrated that PCL-M5 formulation was able to hold the mean arterial pressure variation after phenylephrine administration up to 24 hours. These data demonstrate the sustained antihypertensive effect of the proposed microparticles. Results provided an experimental basis for using PCL-M5 formulation as an oral manidipine carrier. / A manidipina é um bloqueador de canal de cálcio de terceira geração, eficaz no tratamento da hipertensão arterial. Seu uso está relacionado a efeitos metabólicos adicionais de potencial interesse clínico. Entretanto, sua extrema lipofilicidade resulta em propriedades físico-químicas e farmacocinéticas indesejáveis. Assim, torna-se necessário um aprimoramento farmacotécnico para alcançar um avanço expressivo na absorção e na biodisponibilidade desse fármaco. Com esse propósito, o objetivo deste trabalho foi microencapsular a manidipina a fim de evitar sua compartimentalização espontânea nos adipócitos e prolongar seu tempo de trânsito intestinal, com taxas de liberação e duração adequadas para gerar o efeito anti-hipertensivo desejado. Micropartículas de poli(ε-caprolactona) (PCL) e poli(3-hidroxibutirato-co-hidroxivalerato) (PHBV) contendo manidipina foram preparadas com êxito pelo método de emulsão simples/evaporação do solvente orgânico. Diante da ausência de métodos validados para quantificação do fármaco encapsulado nestas micropartículas, um método para o doseamento por cromatografia líquida de alta eficiência com detecção espectrométrica na região do ultravioleta foi previamente desenvolvido e validado. Esse método mostrou-se seletivo, linear (r = 0,9992), preciso (DPR < 2,08 %) e exato (capacidade de recuperação entre 95,02 e 100,41%) no intervalo de 10 a 50 μg.mL-1. Além disso, a cromatografia foi robusta quando submetida a pequenas variações na composição da fase móvel e temperatura da coluna. As quatro formulações apresentaram eficiências de encapsulação superiores a 80% e tamanhos médios de partícula inferiores a 8 μm. Os sistemas microparticulados apresentaram uma forma esférica com superfície lisa e porosa para as formulações de PCL e PHBV, respectivamente. De acordo com as análises por espectroscopia na região do infravermelho com transformada de Fourier, os componentes iniciais não foram quimicamente alterados durante o processo de microencapsulação, ao passo que as análises de difratometria de raios-X e de calorimetria exploratória diferencial demonstraram que esse processo levou a amorfização do fármaco. Os perfis de dissolução in vitro confirmaram a capacidade que as micropartículas apresentam de prolongar a liberação da manidipina, especialmente àquelas preparadas a partir da PCL, que continham 5% de fármaco encapsulado (PCL-M5). Os estudos em animais mostraram que a formulação PCL-M5 foi capaz de minimizar a variação da pressão arterial média, frente à administração de fenilefrina, por até 24 horas. Este dado confirma o efeito anti-hipertensivo prolongado da micropartícula proposta. Os resultados forneceram um embasamento experimental que viabiliza o uso da formulação PCL-M5 como um carreador oral da manidipina.

A nanotecnologia é uma ciência interdisciplinar onde se desenvolve nanomateriais para uso em diversas áreas como a farmácia, cosmética e agroindústria. Um de seus objetivos é aprimorar propriedades de ativos para novas aplicações, por exemplo, através de sistemas para liberação controlada através do uso de biomaterias. Dentre estes biomateriais destaca-se o poliácido lático (PLA) que é constantemente aplicado como matriz polimérica de várias nanoestruturas para o encapsulamento de ativos. Na área cosmética, ativos como os óleos essenciais são de grande interesse. O óleo essencial de pimenta rosa (Schinus molle L.) é composto por terpenos que apresentam, entre outras, atividade antioxidante e inseticida. No presente trabalho desenvolvemos um novo sistema de nanopartículas de PLA em solução aquosa, para liberação controlada do óleo essencial Schinus molle L. visando a utilização cosmética. As nanopartículas de PLA foram avaliadas quanto a estabilidade através da técnica de espalhamento dinâmico de luz (DLS). A formação foi estudada através do uso de difração de raios X (XRD) e espectroscopia vibracional (FTIR). A morfologia foi observada por microscopia eletrônica de varredura (SEM) comparando-se alguns dos resultados obtidos por DLS. Os resultados obtidos mostraram que o sistema é estável por aproximadamente 100 dias quanto ao tamanho, polidispersão e carga de superfície, mesmo com a variação de pH da solução em relação ao tempo. A estabilidade do nanossistema foi atribuída ao tensoativo dodecil sulfato de sódio (SDS), além da própria semicristalinidade e alta massa molar do PLA. Os componentes do sistema apresentaram interações químicas comprovadas por FTIR. O estudo por SEM mostrou que as nanopartículas obtidas têm aparência esférica, com a matriz polimérica contínua e com vários tamanhos constituindo assim um sistema polidisperso, como observadas também por DLS. A eficiência de encapsulação de 83% avaliada por calorimetria exploratória diferencial (DSC) e a liberação do ativo analisada por gravimetria mostraram-se satisfatórias. O sistema de nanopartículas obtido é estável e, por tanto, com potencial adequado para aplicação em produtos cosméticos. / Nanotechnology is an interdisciplinary science through which nanomaterials are developed for use in areas, such as pharmaceutical, cosmetology and agribusiness. One of its objectives is the improvement in the properties of active compounds for new applications by, for example, systems that use biomaterials for controlled release. Lactic polyacid (PLA), one of such biomaterials, has been constantly applied as a polymer matrix of various nanostructures for the encapsulation of active compounds. In cosmetics, active compounds, as essential oils are of great interest. The essential oil of pimenta rosa (Schinus molle L.) is composed of terpenes, which display antioxidant and insecticide activities. This dissertation addresses the development of a new system of PLA nanoparticles in an aqueous solution for the controlled release of essential oil Shinus molle L. to be applied to cosmetology. The stability of PLA nanoparticles was evaluated by dynamic light scattering (DLS). The formation of the system was studied by X-ray diffraction (XRD) and vibrational spectroscopy (FTIR) and its morphology and polydispersivity were verified by scanning electron microscopy (SEM), comparing some of the results obtained by DLS. The results show that the system is stable for approximately 100 days regarding size, polydispersion and surface charge, even when the pH of the solution varies over time. Stability was assigned to surfactant sodium dodecyl sulfate (SDS), PLA\'s semi crystallinity and high molecular weight. The chemical interactions of the system\'s components were evidenced by FTIR. SEM revealed spherical nanoparticles with a continuous polymeric matrix and polydispersivity, also observed by DLS. Satisfactory results were provided by the 83% of encapsulation efficiency calculated by differential scanning calorimetry (DSC) and the drug release analyzed by gravimetric technique. The nanoparticle system obtained is stable and, therefore, suitable for application to cosmetics.

Ceramics are distinguished from metals and polymers by their inorganic nature and lack of metallic properties. They can be highly crystalline to amorphous, and their physical and chemical properties can vary widely. Ceramics can, for instance, be made to resemble the mineral phase in bone and are therefore an excellent substitute for damaged hard tissue. They can also be made porous, surface active, chemically inert, mechanically strong, optically transparent or biologically resorbable, and all these properties are of interest in the development of new materials intended for a wide variety of applications. In this thesis, the focus was on the development of different ceramics for use in the controlled release of drugs and ions. These concepts were developed to obtain improved therapeutic effects from orally administered opioid drugs, and to reduce the number of implant-related infections as well as to improve the stabilization of prosthetic implants in bone. Geopolymers were used to produce mechanically strong and chemically inert formulations intended for oral administration of opioids. The carriers were developed to allow controlled release of the drugs over several hours, in order to improve the therapeutic effect of the substances in patients with severe chronic pain. The requirement for a stable carrier is a key feature for these drugs, as the rapid release of the entire dose, due to mechanical or chemical damage to the carrier, could have lethal effects on the patient because of the narrow therapeutic window of opioids. It was found that it was possible to profoundly retard drug release and to achieve almost linear release profiles from mesoporous geopolymers when the aluminum/silicon ratio of the precursor particles and the curing temperature were tuned. Ceramic implant coatings were produced via a biomimetic mineralization process and used as carriers for various drugs or as an ion reservoir for local release at the site of the implant. The formation and characteristics of these coatings were examined before they were evaluated as potential drug carriers. It was demonstrated that these coatings were able to carry antibiotics, bisphosphonates and bone morphogenetic proteins to obtain a sustained local effect, as they were slowly released from the coatings. / <p>Felaktigt tryckt som Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology 710</p>

Les liposomes sont des nanovecteurs polyvalents et prometteurs quant à leur utilisation dans plusieurs domaines. Il y a une décennie, un nouveau type de liposome constitué d’amphiphiles monoalkylés et de stérols est né fortuitement dans notre groupe. Ils sont nommés Stérosomes puisqu’ils contiennent une grande proportion de stérols, entre 50 et 70 mol %. Les objectifs de cette thèse sont de développer de nouvelles formulations de Stérosomes ayant des caractéristiques spécifiques et d’acquérir une compréhension plus profonde des règles physicochimiques qui dictent leur comportement de phase. Nous avons spécifiquement examiné le rôle de motifs moléculaires des stérols, de la charge interfaciale et de la capacité à former des liaisons H dans les interactions intermoléculaires menant à l’autoassemblage. Le comportement de phase a été caractérisé par calorimétrie différentielle à balayage (DSC), par spectroscopie infrarouge (IR) et par spectroscopie de résonance magnétique nucléaire du deutérium (²H NMR). Premièrement, nous avons établi certaines corrélations entre la structure des stérols, leur tendance à former des bicouches fluides en présence d'amphiphile monoalkylé et la perméabilité des grandes vésicules unilamellaires (LUV) formées. La nature des stérols module les propriétés de mélange avec de l’acide palmitique (PA). Les stérols portant une chaîne volumineuse en position C17 sont moins aptes à induire des bicouches fluides que ceux qui ont une chaîne plus simple, comme celle du cholestérol. Un grand ordre de la chaîne alkyle de PA est un effet commun à tous les stérols investigués. Il a été démontré que la perméabilité des LUV peut être contrôlée en utilisant des stérols différents. Cependant, ces stérols n’ont aucun impact significatif sur la sensibilité des Stérosomes au pH. Afin de créer des liposomes qui sont sensibles au pH et qui ont une charge positive à la surface, des Stérosomes composés de stéarylamine et de cholestérol (Chol) ont été conçus et caractérisés. Il a été conclu que l’état de protonation de l’amine, dans ce travail, ou du groupe carboxylique, dans un travail précédent, confère une sensibilité au pH et détermine la charge à la surface du liposome. Les premiers Stérosomes complètement neutres ont été fabriqués en utilisant un réseau de fortes liaisons H intermoléculaires. Le groupe sulfoxyde est capable de former de fortes liaisons H avec le cholestérol et les molécules d’eau. Une bicouche fluide métastable a été obtenue, à la température de la pièce, à partir d'un mélange équimolaire d’octadécyl méthyl sulfoxyde (OMSO) et de Chol. Ce comportement distinct a permis d’extruder le mélange pour former des LUV à la température de la pièce. Après 30 h, le temps de vie de la phase métastable, des Stérosomes stables et imperméables existaient toujours sous une forme solide. Un diagramme de température-composition a été proposé afin de résumer le comportement de phase des mélanges d’OMSO/Chol. Finalement, nous avons élaboré des Stérosomes furtifs en incorporant du polyéthylène glycol (PEG) avec une ancre de cholestérol (PEG-Chol) à l’interface de Stérosomes de PA/Chol. Jusqu’à 20 mol % de PEG-Chol peut être introduit sans perturber la structure de la bicouche. La présence du PEG-Chol n’a aucun impact significatif sur la perméabilité de la LUV. L'encapsulation active de la doxorubicine, un médicament contre le cancer, a été réalisée malgré la faible perméabilité de ces LUV et la présence du PEG à l’interface. L’inclusion de PEG a modifié considérablement les propriétés de l’interface et a diminué la libération induite par la variation de pH observée avec des LUV nues de PA/Chol. Cette formulation inédite est potentiellement utile pour l’administration intraveineuse de médicaments. / Liposomes are promising and versatile nanocarriers suitable for potential applications in many fields. A decade ago, a new type of liposomes formed from monoalkylated amphiphiles and sterols was born somehow fortuitously in our group. They are referred to as Sterosomes, because they contain a large proportion of sterols, between 50 and 70 mol %. The objectives of the present thesis are to develop novel Sterosome formulations with specific features, and to gain a deeper understanding of the physicochemical rules that dictate their phase behavior. We have specifically examined the role of the molecular features of sterols, of the interfacial charges and of the H-bond capacity in the intermolecular interactions leading to the self-assembly. The phase behavior was characterized by differential scanning calorimetry (DSC), infrared spectroscopy (IR), and nuclear magnetic resonance spectroscopy of deuterium (2H NMR). First, we have established some correlations between the structure of the sterols, the propensity to form fluid bilayers, and the permeability of the resulting large unilamellar vesicles (LUVs). The nature of the sterol modulates the properties of the mixture with palmitic acid (PA). Sterols bearing a bulky tail chain at C17 are less capable to induce fluid bilayers than those with a non-bulky tail chain, like that of cholesterol. A large ordering of the alkyl chain of PA is an effect exhibited by all of the investigated sterols. It is shown that the permeability of the LUVs can be controlled using different sterols. However, these sterols have no significant impact on the pH-sensitivity of Sterosomes. In order to create liposomes that are pH-sensitive and that have a positive surface charge, Sterosomes composed of stearylamine and cholesterol (Chol) were designed and characterized. It is concluded that the protonation/deprotonation state of the amine (in this work) and carboxylic acid (in previous work) groups confers the pH-sensitivity and determines the surface charge of the liposomes. The first completely neutral Sterosomes were crafted based on the creation of strong intermolecular hydrogen bond networks. The sulfoxide group was capable of forming strong hydrogen bonds with cholesterol and water molecules. In an equimolar octadecyl methyl sulfoxide (OMSO)/Chol mixture, a metastable fluid bilayer was obtained at room temperature. This distinct phase behavior allowed extruding the mixtures to form LUVs at room temperature. After 30 h, the life-time of the metastable phase, stable and impermeable Sterosomes still existed in the solid form. A temperature–composition diagram was proposed to summarize the phase behavior of OMSO/Chol mixtures. Finally, a further step was made to prepare “stealth” Sterosomes by incorporating polyethylene glycol (PEG) with a cholesterol anchor (PEG-Chol) at the interface of PA/Chol Sterosomes. Up to 20 mol % PEG-Chol can be introduced without disturbing the bilayer structure. The presence of PEG-Chol had no significant impact on the permeability of the resulting LUVs. Active-loading of an anti-cancer drug, doxorubicin, can be achieved despite the low permeability of these LUVs and the presence of the PEG at the interface. The inclusion of PEG modified considerably the interface properties and decreased significantly the pH-triggered release observed with naked PA/Chol LUVs. This novel formulation is potentially useful for the application of intravenous administration in the drug delivery field.

Submitted by Johnny Rodrigues (johnnyrodrigues@ufcg.edu.br) on 2018-04-04T20:45:16Z No. of bitstreams: 1 DAYSE DE LOURDES MADRGA ESPÍNOLA GUEDES - DISSERTAÇÃO PPG-CEMat 2014..pdf: 2225179 bytes, checksum: ad9f795a81034cb79500cb575de58f73 (MD5) / Made available in DSpace on 2018-04-04T20:45:16Z (GMT). No. of bitstreams: 1 DAYSE DE LOURDES MADRGA ESPÍNOLA GUEDES - DISSERTAÇÃO PPG-CEMat 2014..pdf: 2225179 bytes, checksum: ad9f795a81034cb79500cb575de58f73 (MD5) Previous issue date: 2014-12-12 / A presente pesquisa tem como objetivo, caracterizar filmes de quitosana, de aplicação sublingual, para uso em sistemas de liberação controlada de fumarato de formoterol., buscando uma nova alternativa para o tratamento emergencial das crises de asma. Sabemos que a asma é uma patologia de grande incidência no Brasil e no mundo, pois existem cerca de 300 milhões de pessoas acometidas pela doença a nível mundial e 20 milhões de brasileiros .É uma doença de caráter hereditário, crônica que não tem cura e que se apresenta muitas vezes como uma emergência médica , pois nas crises da doença o socorro deve ser imediato com o intuito de evitar o óbito do paciente. Hoje utiliza-se apenas a via inalatória como preferencial para administração dos broncodilatadores, visto que essa via tem rapidez de ação. No entando, deparamo-nos com a difícil técnica de utilização dos inaladores que veiculam o medicamento o que muitas vezes impossibilita a sua utilização especialmente em crianças, idosos e pacientes muito debilidados. Vendo esta dificuldade, propusemos com o nosso trabalho buscar uma nova via de utilização dos medicamentos broncodilatadores, que tivesse a mesma eficácia da via inalatória, dispensando a difícil técnica de utilização dos fármacos .Para isso , escolhemos a via sublingual de rápida ação e facilidade de utilização, podendo ser empregada mais adequadamente em uma crise de asma . Selecionamos a quitosana, por ser um biopolímero versátil e muito utilizado em sistema de liberação controlada de fármaco para veicular o formoterol , que é um potente broncodilatador, através da produção de um filme para deposição sublingual. E os resultados obtidos através das caracterizações apresentaram membranas com variações de cristalinidade (por DRX) de acordo com o processo de reticulação, além de apresentarem uma possível relação entre reticulação e liberação. Por FTIR pode-se observar certa interação entre o fármaco e os grupos amina da quitosana, assim como possível isomerização do fármaco pela reticulação com 5% de TPP. Pelas microscopias ótica e eletrônica, pode-se observar que o acréscimo de fármaco proporcionou alguma rugosidade a membrana. Também pelas microscopias verificou-se a reticulação não homogênea da superfície da membrana. Por EDS não se verificou nenhum elemento estranho a estrutura da quitosana e do fármaco. Por medida do ângulo de molhabilidade pode-se verificar aumento do perfil hidrofílico da membrana por adição do fármaco, perfil este que não foi modificado pelo processo de reticulação. O ensaio de citotoxicidade apresentou resultados que indicam a membrana como promissora candidata a testes in vivo. / This research aims to characterize chitosan films, sublingual application, for use in controlled release of formoterol fumarate systems., Looking for a new alternative for the emergency treatment of asthma attacks. We know that asthma is a disease of high incidence in Brazil and in the world, because we have about 300milhões of people with the disease worldwide and 20 million Brazilians .It is one hereditary disease, chronic that has no cure and that often presents as a medical emergency, because the crisis of the disease the relief should be immediate in order to prevent the death of the patient. Today only is used inhalation as preferred for administration of bronchodilators, since this route has faster action .In entando, we are faced with the difficult technique for using inhalers that deliver the medicine which often makes it impossible to use especially in children, the elderly and very debilidados patients. Buy this difficulty, we proposed in our work to seek a new route for the use of bronchodilators, which had the same effectiveness of inhaled, eliminating the difficult technique of using drugs .For this, choose the sublingual route of fast action and ease of use and can be used more appropriately in an asthma attack. Chitosan selected because it is a versatile and widely used biopolymer for controlled drug delivery system for conveying formoterol, which is a potent bronchodilator, by producing a film for sublingual deposition. And the results obtained from the characterization showed membranes crystallinity variations (XRD) according to the crosslinking process, besides presenting a possible relationship between cross-linking and release. By FTIR one can observe some interaction between the drug and amino groups of chitosan, and can isomerization of drug by crosslinking with 5% TPP. Through optical and electronic microscopy, it can be seen that addition of drug has provided some roughness to the membrane. Also by microscopy verified the inhomogeneous crosslinking of the membrane surface. EDS there was no foreign object the structure of chitosan and the drug. By measuring the wetting angle can be checked increase the hydrophilic profile of the membrane by addition of the drug, this profile has not been modified by crosslinking process. The cytotoxicity assay results presented indicate that the membrane as a promising candidate for in vivo testing.

Cette étude concerne le développement de nanoparticules hybrides offrant de nouvelles stratégies pour la thérapie et le diagnostic médical. Elles sont constituées d’un cœur magnétique jouant le rôle d’agent de contraste pour l’IRM et d’inducteur de chaleur par hyperthermie, d’une couronne de polymère thermosensible permettant d’encapsuler des principes actifs et de peptides de reconnaissance biologique. Une grande partie de l’étude a consisté à étudier les processus d'adsorption de copolymères poly(éther)-b-poly(L-lysine) de composition variable sur les particules magnétiques et à comprendre le rôle de la conformation des chaînes polymère à la surface des particules sur la stabilité des colloïdes en milieu physiologique. Un agent antitumoral a été encapsulé puis libéré de façon contrôlée sous l’effet d’un champ magnétique alternatif en exploitant le caractère thermosensible des blocs polyéthers. Des séquences peptidiques ciblant les zones d’inflammation de la barrière hémato-encéphalique ont été greffées sur les copolymères. L’efficacité du ciblage a été validée par IRM et fluorescence sur un modèle animal démontrant ainsi la multifonctionnalité des nanoparticules. / This work deals with the development of hybrid nanoparticles that could offer new strategies for therapy and diagnostic. These are based on a magnetic core which can play the role of contrast agent for MRI as well as heat inductor in AC magnetic field. This inorganic core is surrounded by a thermo-responsive polymeric brush that controls the loading and the release of drugs, and can be functionalized by specific ligands ensuring the targeting specificity. A large part of this work consists in studying the adsorption mechanism of poly(ether)-b-poly(L-lysine) based block copolymers onto magnetic particle and to better understand the influence of the polymer chain conformation at particles surface on the colloidal stability under physiological conditions. An anticancer drug has been loaded and released in a controlled manner under alternative magnetic field by taking advantage from the thermosensitivity of the polyether block. Targeting peptides specific of inflammation sites at the blood brain barrier have been grafted onto copolymers. The targeting specificity has been demonstrated by MRI and fluorescence imaging in rats attesting the multifunctionality of such nanoparticles.

Idebenone is an antioxidant, a synthetic derivative of coenzyme Q10, with several applications, such as neuroprotection. However, this drug has low solubility in water, besides is irritant substance and has chemical instability. Hence, idebenone-loaded nano-organized systems have been developed, such as polymeric nanocapsules (NC). Vegetable oils containing antioxidants such as coconut oil and palm oil can be interesting for the composition of these particles. In this way, the aim of this work was to develop NC suspensions containing different oils as core (palm, coconut or medium chain triglycerides) for delivery of neuroprotective agent idebenone in order to compare the behavior of these systems concerning physico-chemical stability, photostability, controlled release, and conversion to redispersible solid dosage forms (lyophilized products). The nanocapsules were prepared by interfacial deposition of preformed polymer. As the results, it was possible to prepare poly(Ɛ-caprolactone) NC suspensions and palm oil (PO/PCL) or Eudragit® RS100 and coconut oil (OC/EUD) containing idebenone (1.0 mg/mL) with appropriate physico-chemical characteristics. Parameters such as the proportion of aqueous phase/organic phase, type of both surfactant (low HLB) and polymer influenced the optimization of these systems. For comparison, corresponding formulations were prepared with medium chain triglycerides (TCM/PCL or TCM/EUD), using the same conditions. The suspensions had an average diameter between 166 and 216nm, low polydispersity index (0.085 to 0.142), positive or negative zeta potential, depending on the characteristics of the polymer, and high encapsulation efficiency. The maintenance of average particle diameter and low polydispersity index have be verified during stability study (room temperature and exposed or not to light) for 75 days. However, the idebenone content significantly decreased in this period, with influence on the type of polymer. Thereafter, photostability study has shown that the suspensions NC OP/PCL (UVC/UVA) and TCM/PCL (UVA) were able to significantly reduce the degradation of idebenone (content: 53,7-76,1%) compared to an aqueous micellar (content: 31,2-63,1%) dispersion containing the drug. In addition, these systems were able to promoting drug controlled release (t1/2 26 h), without burst effect, showing monoexponential profile (t1/2< 3.0 h for free drug). The lyophilization of suspensions, employing trehalose as soluble carbohydrate, resulted in suitable and redispersible products (content of 96-100%, less than 3.6% moisture; 0.8-1.2 index), presenting several spherical structures, including in colloidal range, featuring the presence of NC in these dried products. In the stability study (room temperature/protection from light and moisture), it was observed that the lyophilized products were able to delay or decrease the degradation of idebenone compared to suspensions of origin, regardless of the both type of polymer (PCL/EUD) and oil (OP/OC/TCM). In conclusion, the developed systems are promising for the controlled release of neuroprotective drug idebenone. / A idebenona é um antioxidante, derivado sintético da coenzima Q10, com várias aplicações, como em neuroproteção. No entanto, este fármaco possui baixa solubilidade em água, potencial irritativo e instabilidade química, fato que tem despertado o interesse em sua associação a sistemas nano-organizados. Dentre estes, destacam-se as nanocápsulas poliméricas (NC). Óleos vegetais, contendo compostos antioxidantes, como óleo de coco e de palma, podem ser interessantes para a composição destas partículas. Neste sentido, o objetivo deste trabalho foi desenvolver suspensões de NC contendo diferentes óleos como núcleo (palma, coco ou triglicerídeos de cadeia média), almejando à veiculação do neuroprotetor idebenona, de forma a comparar o comportamento dos sistemas quanto à estabilidade físico-química, fotoestabilidade, controle de liberação, além da conversão em formas farmacêuticas sólidas redispersíveis (liofilizados). As NC foram preparadas pelo método de deposição interfacial de polímero pré-formado. Conforme os resultados, foi possível preparar suspensões de NC de poli(ε-caprolactona) e óleo de palma (OP/PCL) ou de Eudragit® RS100 e óleo de coco (OC/EUD), contendo idebenona (1,0 mg/mL), com características físico-químicas adequadas, sendo que fatores como proporção das fases aquosa/orgânica, tipo de tensoativo de baixo EHL e de polímero influenciaram a otimização dos sistemas. Para fins comparativos, formulações correspondentes foram preparadas com triglicerídeos de cadeia média (TCM/PCL ou TCM/EUD), empregando as mesmas condições. As suspensões apresentaram diâmetros médios entre 166 e 216 nm, baixos índices de polidispersão (0,085-0,142), potencial zeta positivo ou negativo, dependendo das características do polímero e elevada eficiência de encapsulamento. Quando estas suspensões foram submetidas a estudo de estabilidade, à temperatura ambiente e expostas ou não à luz, durante 75 dias, verificou-se manutenção dos diâmetros médios de partículas e baixos índices de polidispersão. Entretanto, o teor de idebenona decaiu significativamente neste período, com influência significativa do tipo de polímero. Após, estudo de fotoestabilidade demonstrou que as suspensões de NC OP/PCL (UVC/UVA) e TCM/PCL (UVA) foram capazes de reduzir significativamente a degradação da idebenona (teor remanescente: 53,7-76,1%) em comparação a uma dispersão micelar aquosa contendo o fármaco (teor remanescente: 31,2-63,1%), além de promoverem liberação controlada da mesma (t1/2 26 h), sem efeito burst, com perfil ajustado ao modelo monoexponencial (t1/2<3,0 h para fármaco livre). A liofilização das suspensões, empregando trealose, um carboidrato solúvel, resultou em produtos adequados (teor entre 96-100 %; umidade inferior a 3,6 %), redispersíveis (índice de ressuspensão entre 0,8-1,2) e com a presença de inúmeras estruturas esféricas, inclusive na faixa coloidal, caracterizando a presença das NC nestes produtos secos. No estudo de estabilidade (temperatura ambiente/proteção da luz e da umidade), observou-se que os produtos liofilizados foram capazes de retardar ou diminuir significativamente a degradação da idebenona em comparação às suspensões de origem, independentemente do tipo de polímero (PCL/EUD) e de óleo (OP/OC/TCM). Sendo assim, os sistemas desenvolvidos são promissores para a liberação controlada do neuroprotetor idebenona.