Many biological processes, pathogens, and pharmaceuticals act upon, cellular membranes. Accordingly, cell membrane mimics are attractive targets for biosensing, with research, pathology, and pharmacology applications. Lipid bilayers represent a versatile sensor functionalization platform providing antifouling properties, and many receptor integration options, uniquely including transmembrane proteins. Bilayer-coated sensors enable the kinetic characterization of membrane/analyte interactions. Addressed theoretically and experimentally is the self-assembly of model membranes on plasmonic sensors. Two categories of plasmonic sensors are studied in two parts. Part I aims to deposit raft-forming bilayers on planar nanoaperture arrays suitable for multiplexing and device integration. By vesicle fusion, planar bilayers are self-assembled on thiol-acid modified flame-annealed gold without the need for specific lipid head-group requirements. Identification of coexisting lipid phases is accomplished by AFM imaging and force spectroscopy mapping. These methods are successfully extended to metallic, plasmon-active nanohole arrays, nanoslit arrays and annular aperture arrays, with coexisting phases observed among the holes. Vis-NIR transmission spectra of the arrays are measured before and after deposition, indicating bilayer detection. Finally, the extraction of membrane proteins from cell cultures and incorporation into model supported bilayers is demonstrated. These natural membrane proteins potentially act as lipid-bound surface receptors. Part II aims to encapsulate in model lipid bilayers, metallic nanoparticles, which are used as probes in surface enhanced Raman spectroscopy. Three strategies of encapsulating particles, and incorporating Raman-active dyes are demonstrated, each using a different dye: malachite green, rhodamine-PE, and Tryptophan. Dye incorporation is verified by SERS and the bilayer is visualized and measured by TEM, with support from DLS and UV-Vis spectroscopy. In both parts, lipid-coated sensors are successfully fabricated and characterized. These results represent important and novel solutions to the functionalization of plasmonic surfaces with biologically relevant cell membrane mimics.

No description available.

abstract: Biological membranes are critical to cell sustainability by selectively permeating polar molecules into the intracellular space and providing protection to the interior organelles. Biomimetic membranes (model cell membranes) are often used to fundamentally study the lipid bilayer backbone structure of the biological membrane. Lipid bilayer membranes are often supported using inorganic materials in an effort to improve membrane stability and for application to novel biosensing platforms. Published literature has shown that a variety of dense inorganic materials with various surface properties have been investigated for the study of biomimetic membranes. However, literature does not adequately address the effect of porous materials or supports with varying macroscopic geometries on lipid bilayer membrane behavior. The objective of this dissertation is to present a fundamental study on the synthesis of lipid bilayer membranes supported by novel inorganic supports in an effort to expand the number of available supports for biosensing technology. There are two fundamental areas covered including: (1) synthesis of lipid bilayer membranes on porous inorganic materials and (2) synthesis and characterization of cylindrically supported lipid bilayer membranes. The lipid bilayer membrane formation behavior on various porous supports was studied via direct mass adsorption using a quartz crystal microbalance. Experimental results demonstrate significantly different membrane formation behaviors on the porous inorganic supports. A lipid bilayer membrane structure was formed only on SiO2 based surfaces (dense SiO2 and silicalite, basic conditions) and gamma-alumina (acidic conditions). Vesicle monolayer adsorption was observed on gamma-alumina (basic conditions), and yttria stabilized zirconia (YSZ) of varying roughness. Parameters such as buffer pH, surface chemistry and surface roughness were found to have a significant impact on the vesicle adsorption kinetics. Experimental and modeling work was conducted to study formation and characterization of cylindrically supported lipid bilayer membranes. A novel sensing technique (long-period fiber grating refractometry) was utilized to measure the formation mechanism of lipid bilayer membranes on an optical fiber. It was found that the membrane formation kinetics on the fiber was similar to its planar SiO2 counterpart. Fluorescence measurements verified membrane transport behavior and found that characterization artifacts affected the measured transport behavior. / Dissertation/Thesis / Ph.D. Chemical Engineering 2011

Neste estudo investigamos os efeitos dos ácidos graxos sobre a função e sinalização intracelular de linfócitos humanos. Os ácidos oléico (OA) e linoléico (LA), em baixas concentrações, estimularam a proliferação celular induzida pela IL-2 através do aumento da fosforilação da proteína PKC-<font face=\"symbol\">Z que levou a um aumento da fosforilação de ERK 1/2. Já os ácidos palmítico (PA), esteárico (SA), DHA e EPA diminuíram a proliferação destas células e inibiram a fosforilação de JAK1 e 3, STAT5, ERK e Akt. Os resultados obtidos são sugestivos de que o efeito inibitório promovido por PA, SA, DHA e EPA sobre a proliferação de linfócitos ocorreu devido à diminuição da fosforilação de proteínas fundamentais para a proliferação celular. Por outro lado, OA e LA estimularam a proliferação de linfócitos aumentando a fosforilação de ERK 1/2 através da ativação de PKC-<font face=\"symbol\">Z, efeito dependente da PI3K. O efeito inibitório promovido pelo DHA está associado a uma alteração na quantidade de lipid rafts na membrana plasmática nos quais o receptor de IL-2 está localizado. / The effect of fatty acids (FA) on interleukin -2 (IL-2) signaling pathway in human lymphocytes was investigated. Docosahexaenoic (DHA), eicosapentaenoic (EPA), palmitic (PA) and stearic (SA) acids decreased lymphocyte proliferation in concentrations above 50 <font face=\"symbol\">mM. However, oleic (OA) and linoleic (LA) acids increase lymphocyte proliferation at 25 <font face=\"symbol\">mM. PA, SA, DHA and EPA decreased JAK 1, JAK 3, STAT 5 and AKT phosphorylation induced by IL-2 but OA and LA did not cause any effect. OA and LA increased ERK1/2 phosphorylation whereas the other FA caused a marked decrease. PKC-<font face=\"symbol\">Z phosphorylation was decreased by OA and LA only. In conclusion, the inhibitory effect of PA, SA, DHA and EPA on lymphocyte proliferation observed in our previous study was due to a decrease in protein phosphorylation activated by IL-2. Probably, OA and LA stimulated lymphocyte proliferation by increasing ERK 1/2 phosphorylation throught PKC-<font face=\"symbol\">Z activation. The inhibition of JAK 1, JAK3, STAT 5, ERK1/2 and Akt phosphorylation caused by DHA is associated to a decrease in membrane lipid rafts contend.

Orientador: Francisco Benedito Teixeira Pessine / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Química / Made available in DSpace on 2018-08-23T23:52:35Z (GMT). No. of bitstreams: 1 Sousa_Marcelode_D.pdf: 3494030 bytes, checksum: 462ff3b363ece6e2ff2f83e5d1028485 (MD5) Previous issue date: 2013 / Resumo: Nos dias atuais não há cura e nem vacina para as pessoas portadoras de HIV. A erradicação do vírus não é possível porque a maioria está depositado em órgãos que são de difícil acesso aos fármacos antirretrovirais. Uma alternativa seria direcionar os fármacos à estes órgãos por intermédio de nanocarreadores. Os fármacos utilizados neste trabalho foram a Nevirapina, o Saquinavir e o Efavirenz e o nanocarregador foi as Nanopartículas Lipídicas Sólidas (NLS). As NLS foram produzidas utilizando ácido esteárico, ácido mirístico e Compritol 888 ATO como matrizes dos nanocarregadores, brometo de cetiltrimetilamônio, Lipoid-S75 e Tween 80 como surfatantes e n-butanol como co-surfatante. A formulação otimizada foi obtida através de um planejamento experimental 2 com ponto central utilizando os surfatantes como variáveis. A molécula direcionadora adicionada na superfície das nanopartículas foi a d-manose, a qual estava ligada na octadecilamina. Este açúcar foi escolhido por que é receptor dos macrófagos/monócitos. A estratégia é que estas células capturem os nanocarregadores carregados com fármacos antirretrovirais e os enviem aos órgãos depósitos de HIV. Estas NLS foram caracterizados pelas técnicas de espalhamento dinâmico de luz, potencial Zeta, Calorimetria Diferencial de Varredura (DSC), Difratometria de raios-X e Microscopia Eletrônica de Varredura (MEV), além dos estudos de liberação in vitro. / Abstract: Nowadays there is neither cure nor vaccine for people living with HIV. However, virus eradication is not possible because most are deposited in organs that are difficult access to antiretroviral drugs. An alternative would be to target the drugs to these organs via nanocarriers. The drugs used in this work were Nevirapine, Saquinavir and Efavirenz and the nanocarriers were Solid Lipid Nanoparticles (SLN). The SLN were produced using stearic acid, myristic acid and Compritol 888 ATO as matrix of nanocarriers, cetyltrimethyl ammonium bromide, Lipoid-S75 and Tween 80 as surfactants and n-butanol as cosurfactant. The optimized formulation was obtained through an 2 experimental design with central point using surfactants as variable. The target molecule added in the nanocarriers surface was d-mannose, which was linked in the octadecylamine. This sugar was chosen because it is receptor of macrophages/monocytes. The strategy is that these cells capture the nanocarriers loaded antiretroviral drugs and it send deposit organs of HIV. These SLN were characterized by techniques dynamic light scattering (DLS), zeta Potential, Differential Scanning Calorimetry (DSC), X-ray diffraction and Scanning Electron Microscopy (MEV), beyond of in vitro released studies. / Doutorado / Físico-Química / Doutor em Ciências

Orientadores: Eneida de Paula, Daniele Ribeiro de Araújo / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Biologia / Made available in DSpace on 2018-08-24T00:52:12Z (GMT). No. of bitstreams: 1 Barbosa_RaqueldeMelo_D.pdf: 5424104 bytes, checksum: a7f0888c7fb32138387068083d5bf74f (MD5) Previous issue date: 2013 / Resumo: Nanopartículas lipídicas sólidas (SLN) e carreadores lipídicos nanoestruturados (NLC) têm sido utilizados com sucesso como sistemas de liberação modificada. O anestésico local dibucaína (DBC) foi encapsulado em SLN e NLC objetivando aplicação tópica, para melhora de sua disponibilidade redução de efeitos adversos. As nanopartículas lipídicas foram preparadas pelas técnicas de sonicação (Son) ou homogeinização à alta pressão (HP), sendo utilizados palmitato de cetila (CP) ou miristato de miristila (MM) como matrizes lipídicas sólidas, acrescidos (NLC) ou não (SLN) de uma mistura de triglicerídeos de ácido cáprico e caprílico; poloxamer 188 foi usado como tensoativo. A DBC encapsulada foi quantificada por metodologia validada por cromatografia líquida de alta eficiência. As análises físico-químicas compreenderam diâmetro médio, potencial zeta, distribuição de tamanhos e morfologia das nanopartículas, percentual de encapsulação além de medidas de calorimetria exploratória de varredura (DSC), espectroscopia de infravermelho (FTIR), ressonância paramagnética eletrônica (RPE) e difração de raios X à baixo ângulo (SAXS). Medidas in vitro do perfil de liberação do fármaco, da estimativa de fluxo, deformação e elasticidade das partículas através de membranas artificiais e de toxicidade em cultura de células (fibloblastos 3T3 e queratinócitos HaCat) foram feitas. A estabilidade das amostras foi avaliada em função do tempo e testes de antinocicepção (tail flick, em ratos Wistar) foram usados para avaliar a atividade terapêutica in vivo. O diâmetro médio das partículas de SLN e NLC produzidas foi similar (ca. 200nm). A estabilidade física das nanopartículas foi satisfatória por até 240 dias de armazenamento a 4 ºC, principalmente para NLCMM/HP com e sem DBC, sugerindo que a metodologia de HP produz partículas mais estáveis. Todas as formulações apresentaram eficiência de encapsulação maior que 70%, sendo que NLCMMDBC/HP apresentou a maior encapsulação (90,54 ± 0,95%). Medidas de FTIR e DSC revelaram a DBC molecularmente dispersa na matriz lipídica das nanopartículas. Quanto à organização molecular das SLN e NLC, resultados de SAXS indicaram a existência de arranjos lipídicos lamelares no interior das SLN, não alterados pela adição da DBC; as medidas de RPE com marcadores de spin doxil-estearato revelaram espectros compatíveis com bicamadas, com maior organização molecular dos lipídios das SLN e NLC, após inserção da DBC. Ensaios in vitro confirmaram a liberação modificada da dibucaína associada às partículas, governada por difusão de Fick. Tanto a elasticidade quanto o fluxo das partículas in vitro apresentaram baixos valores evidenciando deposição das mesmas nas membranas com poros de 30 nm. A citotoxicidade intrínsica da DBC sobre ambos os tipos celulares foi reduzida após encapsulação nas SLN e NLC. O efeito analgésico in vivo da DBC a 0,05% aplicada topicamente (dispersa em gel de carbopol) aumentou significativamente após encapsulação nas formulações, em particular para SLNCPDBC liofilizada com o crioprotetor maltose. Assim, formulações de dibucaína em SLN ou NLC, preparadas com MM ou CP mostraram-se promissoras como bases para produtos farmacêuticos de liberação modificada, para anestesia dérmica / Abstract: Solid lipid nanoparticles (SLN) and nanostructured lipid carriers (NLC), intended for topical application, were successfully prepared as sustained release systems for the encapsulation of the local anesthetic dibucaine (DBC), aiming to reduce its toxic effects and to improve its availability. The particles were prepared by two differents procedures: sonication (Son) or high pressure homogenization (HP), employing either cetyl palmitate (CP) or myristyl myristate (MM) as the solid lipid matrix, in the presence (NLC) or absence (SLN) of a mixture of capric and caprylic acids; poloxamer 188 was used as surfactant. DBC was quantified through a validated HPLC procedure. Physico-chemical analysis of the nanoparticles included measurements of size distribution, zeta potential, morphology, DBC encapsulation efficiency, as well as exploratory scanning calorimetry (DSC), infrared spectroscopy (FTIR), electron paramagnetic resonance (EPR) and small angle X-ray scattering (SAXS) tests. In vitro analysis of the release profile, flow and elasticity of the particles were performed through artificial membranes while toxicity was tested in 3T3 fibroblasts and HaCaT keratinocytes in culture. Stability of the formulations as a function of time was also measured. The therapeutic activity of the formulations was determined using antinociception tests (tail flick) in Wistar rats. SLN and NLC produced by both methodologies were similar (~200 nm), but HP produced more stable nanoparticles. The physical stability of the nanoparticles was satisfactory during a storage period of 240 days, especially for NLCMM/HP with or without DBC. All formulations showed encapsulation efficiencies higher than 70%, the greatest being assigned for NLCMMDBC/HP (90.54 ± 0.95%). FTIR and DSC revealed that DBC was molecularly dispersed in the lipid matrix of the nanoparticles. As for the SLN and NLC molecular packing, SAXS diffractrograms indicated the existence of lamellar repeats in SLN core region, which were not disturbed by the addition of DBC while EPR data with doxyl stearate probes revealed spectra compatible with bilayers, with higher molecular order in the presence of DBC. In vitro assays confirmed the prolonged release of dibucaine from the nanoparticles, by Fickian diffusion. Nanoparticles's elasticity and flow were low showing deposition on the surface of 30 nm pore membranes. The intrinsic cytotoxicity of DBC against both cell types was decreased, when encapsulated in SLN and NLC. The in vivo analgesic effect of 0.05% DBC topically applied (dispersed in carbopol gel) was significantly prolonged in the nanoparticle formulations, largely for SLNCPDBC lyophilized with maltosis as crioprotector. In conclusion, dibucaine formulations in SLN or NLC prepared with MM or CP are promising for the development of pharmaceutical products intended for prolonged dermal anesthesia / Doutorado / Bioquimica / Doutora em Biologia Funcional e Molecular

Orientador: Francisco Benedito Teixeira Pessine / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Química / Made available in DSpace on 2018-08-24T01:26:17Z (GMT). No. of bitstreams: 1 Marques_LeticiaPaifer_M.pdf: 4333961 bytes, checksum: dd287508ba192ad95556c2094f8d9d2a (MD5) Previous issue date: 2013 / Resumo: Através de modificações na estrutura química da molécula de pectina cítrica, polissacarídeo utilizado nas indústrias alimentícias como agente gelificante/espessante, foi desenvolvido um Sistema Depot para entrega subcutânea de nanopartículas lipídicas sólidas (NLS) e carreadores lipídicos nanoestruturados (CLN) contendo, respectivamente, Dexametasona (DXM) e Valerato de Betametasona (BTM). Os fármacos foram encapsulados nesses sistemas devido à necessidade de modificar seus perfis de liberação, diminuindo o número de aplicações e sua dosagem, reduzindo ocorrência de efeitos adversos. O produto da reação de oxidação da pectina cítrica foi caracterizado através de Espectroscopia da região do Infravermelho, Análise Termogravimétrica e Calorimetria Diferencial de Varredura. Os resultados indicaram o sucesso da reação, confirmado através da gelificação do hidrogel de pectina cítrica oxidada. As NLS e os CLN apresentaram valores de diâmetro médio em torno de 80nm, alta eficiência de encapsulação e perfis de liberação prolongada; para os CLN o fármaco BTM foi liberado ao longo de 144 horas e para as NLS o fármaco DXM foi liberado ao longo de 24 horas. Estes resultados mostram que as NLS de DXM poderiam ser utilizadas para tratar processos inflamatórios agudos e que os CLN de BTM seriam úteis no tratamento de processos inflamatórios crônicos / Abstract: A modified chemical structure of citrus pectin was used to develop a Depot system for subcutaneuous delivery of solid lipid nanoparticles (SLN) and nanostructured lipid carriers (NLC) containing, respectively, Dexamethasone (DXM) and Betamethasone Valerate (BTM). Citrus pectin is a polysaccharide used in food industry as a gelling/thickener agent. The drugs were encapsulated in this system with the aim to modify their release profiles. This would result in the reduction of the number of applications and dosage. As a consequence, it would also reduce adverse side effects that these drugs may cause. The citrus pectin oxidation product was characterized by Infrared Spectroscopy, Thermogravimetric Analysis and Differential Scanning Calorimetry. The results indicated that the reaction occurred. This was confirmed by gelation of the citrus pectin oxidation product. SLN and CLN showed values with diameters around 80nm, high encapsulation efficiency and sustained release profiles. BTM was released from the CLN over 144 hours and DXM was released from the NLS over 24 hours. These results showed that the DXM-NLS would be useful in the treatment of acute inflammatory processes. BTM-CLN could be applied in the treatment of chronic inflammatory processes / Mestrado / Físico-Química / Mestra em Química

Orientador: Mario Roberto Marostica Junior / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia de Alimentos / Made available in DSpace on 2018-08-19T15:52:41Z (GMT). No. of bitstreams: 1 Marineli_RafaeladaSilva_M.pdf: 1312364 bytes, checksum: 642784e4925126072a876363cda8324f (MD5) Previous issue date: 2012 / Resumo: Têm-se atribuído inúmeros efeitos biológicos ao ácido linoléico conjugado (CLA) e aos fitosteróis. O CLA vem sendo estudado principalmente por sua ação anticarcinogênica, imunomoduladora, reguladora do balanço energético, pela alteração do perfil lipídico e da composição corporal, influência sobre o processo de resistência à insulina e aumento da oxidação lipídica. Os fitosteróis levam a redução dos níveis de colesterol sérico e, consequentemente, a prevenção de doenças cardiovasculares, além de outros efeitos benéficos reportados recentemente, como atividade antidiabetogênica e antioxidante. É possível que a interação entre CLA e fitosteróis melhore ou potencialize os seus efeitos biológicos isolados. O objetivo deste trabalho foi avaliar os efeitos causados pela associação da suplementação de CLA e de fitosteróis no perfil lipídico, hormonal e oxidativo, na sensibilidade à insulina e na composição corporal in vivo. Foi realizado um ensaio biológico com 40 ratos machos Sprague Dawley, saudáveis, em crescimento divididos em 5 grupos (n=8) e alimentados por 9 semanas com dieta normolipídica (AIN-93G) suplementada com 2% dos compostos lipídicos de interesse: grupo S com óleo de soja (padrão), grupo LA com óleo de cártamo (controle), grupo CLA com CLA TonalinÒ, grupo P com fitosteróis Vegapure 95FFÒ e grupo CLA+P com uma mistura de CLA e fitosteróis. Foram determinados e avaliados: ingestão alimentar, ganho de peso, peso dos órgãos, composição corporal, perfil lipídico e hormonal, teste de tolerância à glicose e à insulina, conteúdo de lipídios hepáticos e fecais, enzimas antioxidantes e produtos primários e secundários da autoxidação lipídica. A associação entre CLA e fitosteróis não alterou a ingestão de dieta, ganho de peso, composição corporal, peso dos rins, coração e fígado, mas reduziu o peso do tecido adiposo epididimal (-42%), sem alteração no conteúdo de lipídios hepáticos e perfil lipídico sérico; aumentou a concentração de insulina sérica sem comprometer a sensibilidade à insulina, já que os testes de tolerância à glicose e à insulina e os índices de HOMA-IR não diferiram entre os grupos. Além disso, o consumo isolado da mistura dos isômeros do CLA diminuiu o consumo de dieta, sem alteração do ganho de peso dos animais, reduziu os níveis de leptina sérica e aumentou o peso do fígado dos animais sem alterar o conteúdo de lipídios hepáticos. O consumo isolado de fitosteróis reduziu a glicose sanguínea, melhorando o índice de HOMA-BCF, e aumentou a excreção de lipídios fecais em 6 vezes, com ou sem a adição de CLA. Quanto ao perfil oxidativo, o grupo CLA+P não apresentou alteração nos valores plasmáticos de MDA e GSH, na atividade das enzimas SOD, GRd e GPx, mas restaurou os níveis de isoprostana e a atividade de catalase aos valores basais, as quais estiveram aumentadas com a suplementação de CLA. A suplementação com CLA+P também reduziu os produtos primários e secundários da peroxidação lipídica no fígado. A suplementação isolada de fitosteróis e de CLA também foi capaz de reduzir a peroxidação lipídica no fígado dos animais e os valores plasmáticos de MDA. Tendo em vista os resultados encontrados, pôde-se concluir que a associação entre a suplementação de CLA e fitosteróis não apresentou efeito sobre a composição corporal, perfil hormonal e lipídico, mas atuou positivamente na redução do tecido adiposo, sem comprometer a sensibilidade à insulina e induzir a hepatomegalia ou esteatose hepática. Além disso, o efeito sinérgico entre esses compostos melhorou o perfil oxidativo e reduziu a peroxidação lipídica nos animais. Porém, os mecanismos responsáveis por tais alterações não foram elucidados, sendo necessárias outras investigações / Abstract: Several biological effects have been assigned to the conjugated linoleic acid (CLA) and phytosterols. CLA has been studied mainly by anticarcinogenic actions, immunomodulatory, regulation of energy balance, modulation of circulating lipids and body composition, influence on the process of insulin resistance and increase in lipid oxidation. Phytosterols provide a reduction in serum cholesterol levels and prevent cardiovascular disease, and other biological effects reported recently, as antidiabetic and antioxidant activity. It is possible that the interaction between CLA and phytosterols improves or potentiate their isolated effects. The aim of this work was to evaluate the effects of dietary CLA associated with phytosterols on lipid, hormonal and oxidative profile, insulin sensitivity and body composition in vivo. A biological assay was conducted with 40 male healthy Sprague Dawley rats divided into 5 groups (n = 8) and fed for 9 weeks with a standard lipid diet (AIN-93G) supplemented with 2% of lipid compounds of interest: group S with soybean oil (standard), group LA with safflower oil (control), group CLA with CLA TonalinÒ, group P with phytosterols Vegarupe 95FFÒ, and group CLA+P with a mixture of CLA and phytosterols. Food intake, weight gain, organs weight, body composition, lipid and hormonal profile, glucose tolerance test and insulin tolerance test, hepatic and fecal lipid content, antioxidant enzymes, primary and secondary lipid autoxidation products were determined. The association between CLA and phytosterols did not alter food intake, weight gain, body composition, kidneys, heart and liver weight, but reduced epididymal adipose tissue weight (-42%), without change in hepatic lipids content and lipid profile, increased serum insulin concentration, without impairment of insulin sensitivity, since the glucose tolerance test, insulin tolerance test and HOMA-IR index did not differ among the groups. In addition, the isolated consumption of mixture CLA isomers reduced food intake, without alter the weight gain of animals, reduced serum leptin and increased animals liver weight without change the hepatic lipid content. And the isolated consumption of phytosterols reduced blood glucose, improving the HOMA-BCF index, and increased lipid fecal excretion by 6 times, with or without the addition of CLA. For the oxidative profile, CLA+P group showed no change in plasma MDA and GSH levels, SOD, GPx and GRd activity, but restored the levels of isoprostane and catalase activity to baseline, which were increased with CLA supplementation. Supplementation with CLA+P also reduced the primary and secondary products of lipid peroxidation in the liver. Supplementation of isolated phytosterols and CLA was also able to reduce lipid peroxidation in liver and plasma levels of MDA. We concluded that the association between phytosterols and CLA supplementation had no effect on body composition, hormonal and lipid profile, but acted positively on the reduction of adipose tissue without impairment of insulin sensitivity and hepatic steatosis or hepatomegaly. In addition, the synergistic effect between these compounds improved the oxidative profile and reduced lipid peroxidation in animals. However, the mechanisms responsible for these changes were not elucidated, so further investigations are necessary / Mestrado / Nutrição Experimental e Aplicada à Tecnologia de Alimentos / Mestre em Alimentos e Nutrição

Les membranes cellulaires sont des systèmes complexes composés de lipides variés qui interagissent avec les protéines pour accomplir une fonction. Leur adressage spécifique dans la cellule est crucial pour le fonctionnement cellulaire. Les vésicules COP (coat protein) sont impliquées dans leur transport dans les premières étapes de la voie de sécrétion. Récemment, une interaction très spécifique a été identifiée entre le domaine transmembranaire de la protéine p24 (p24TMD) abondante dans la membrane des vésicules COP et la sphingomyéline C18:0. Cette spécificité a été identifiée dans le cas d’interaction protéine-protéine et protéine-acide nucléique comme impliquée dans la régulation de fonctions cellulaires, C’est pourquoi nous avons décidé d'étudier sur cette interaction. A cet effet, le p24TMD a été obtenu par synthèse chimique et sa structure étudiée par RMN du solide en présence de la sphingomyèline avec pour but ultime de comprendre la fonction. / Cell membranes are complex systems composed of variety of lipids that interacts with proteins to trigger cellular function. The delivery of these lipids to the right compartment is crucial for cells to work efficiently. The coat protein (COP) complex vesicles are involved in lipids traffic in the early stages of the secretory pathway. Recently, a highly specific interaction has been found between the transmembrane domain of p24 protein (p24TMD) abundant in COPI membrane and sphingomyelin C18:0. As such highly specific interaction have been reported for protein-protein and protein-nucleic acid interactions to be involved in regulation of cell functions, we decide to investigate this specific interaction. The p24TMD was obtained chemically and investigated by solid state NMR in presence of sphingomyelin with the ultimately goal to understand the function behind.

Les écrans solaires sont des formulations dont l’application permet de protéger la peau des effets néfastes du rayonnement ultraviolet (UV) et notamment de l’apparition des cancers cutanés. Ces formulations contiennent des filtres UV organiques et/ou inorganiques. Certains filtres UV organiques sont connus pour pénétrer la peau et engendrer des réactions allergiques et photo-allergiques. De plus, certains d’entre eux peuvent engendrer des effets toxiques sur les cellules cutanées vivantes et atteindre la circulation systémique. Les filtres UV inorganiques sont la plupart du temps incorporés dans les écrans solaires sous forme de nanoparticules afin d’améliorer les qualités esthétiques des écrans solaires minéraux. Les nanoparticules utilisées comme filtres UV inorganiques exerceraient des effets toxiques sur les cellules nucléées de la peau. Les nanoparticules et nanocapsules lipidiques sont des particules lipidiques submicroniques intéressantes pour formuler les actifs pharmaceutiques et cosmétiques et notamment les filtres UV. L’objectif de ce travail était de développer des suspensions de nanoparticules lipidiques pour formuler des filtres UV inorganiques et organiques en les maintenant à la surface de la peau tout en augmentant leur efficacité photo-protectrice. Ces travaux ont permis de développer des suspensions de nanoparticules lipidiques encapsulant des filtres UV inorganiques en augmentant leur pouvoir photo-protecteur. Cette étude a également mis en évidence l’intérêt de ces suspensions de nanoparticules lipidiques pour encapsuler un filtre UV organique et limiter sa perméation percutanée tout en augmentant son efficacité filtrante dans le domaine UV / Sunscreens are topical formulations that protect the skin against damages induced by ultraviolet (UV) radiations and notably skin cancers formation. Those formulations contain organic and/or inorganic UV filters. Some organic UV filters are known to penetrate the skin and trigger allergic and photo-allergic cutaneous reactions. Moreover, some of them are responsible for toxic effects on skin nucleated cells and could reach systemic circulation. Nanoparticles of inorganic UV filters are often incorporated into sunscreens to improve their aesthetic qualities. Nanoparticles used as inorganic UV filters could exercise toxic effects on skin nucleated cells. Lipid nanoparticles and nanocapsules are submicronic lipid particles interesting to formulate pharmaceutical and cosmetic active compounds and notably UV filters. The aim of this work was to develop lipid nanoparticles to entrap organic and inorganic UV filters maintaining them at skin surface while increasing their photo-protection efficiency. This study permitted to develop lipid nanoparticle suspensions entrapping inorganic UV filters enhancing their photo-protection efficiency. This work also highlighted the interest of these lipid nanoparticle suspensions to entrap an organic UV filter avoiding its percutaneous permeation while enhancing its photo-protection efficiency