A Terapia Fotodinâmica é um tratamento promissor no cura de várias doenças oftalmológicas e dermatológicas, assim como tumores. Este tratamento utiliza a combinação de luz e um composto fotossensível na presença de oxigênio. Neste trabalho objetivamos entender mecanismos de fotossensibilização em membranas. Para isso, estudamos os efeitos de irradiação em Vesículas Unilamelares Gigantes (GUVs) compostas de POPC e Cardiolipina (CL) e POPC e Colesterol (Col), contendo uma molécula fotoativa (diC12-porf) ancorada à superfície dessas membranas. GUVs compostas por POPC e POPC:Col na presença da molécula fotoativa reagem ao estímulo da luz exibindo um aumento de área seguido de flutuações. O mesmo foi observado para membranas de POPC contendo menos que 50mol% de CL. Já para composições contendo 50mol% de CL, a membrana passa a formar domínios lipídicos podendo ou não ser destruída durante a irradiação. Estes domínios podem ser suprimidos com a adição de EDTA (agente quelante de íons divalentes) na solução. Ao adicionarmos CaCl2 ao meio externo das GUVs contendo EDTA, percebemos que o efeito dos domínios e destruição da membrana reaparece. Tal fato evidencia que íons Ca++ presentes em solução devem complexar com as cargas da CL, levando à formação de domínios lipídicos. Ao quantificar o aumento de área sofrido pelas membranas percebemos que a presença de CL na membrana de POPC inibe o aumento de área para concentrações acima de 40mol% de CL. Já a presença de Col na membrana parece não contribuir significativamente para o aumento de área, embora o mesmo sofra oxidação. Além disso, evidenciou-se que na presença de CL/Col o tempo de fotoclareamento de diC12-porf é muito maior do que na ausência destes. Estes resultados evidenciam que a inclusão de CL na membrana oferece um número maior de sítios de reação para o oxigênio singlete reduzindo a foto-degradação da molécula fotoativa. Já a inclusão de Col aumenta o tempo de vida da molécula fotoativa provavelmente devido ao fato da dupla ligação do Col estar mais próxima ao centro produtor de oxigênio singlete do que a dupla ligação do POPC. / Photodynamic Therapy is a promising treatment for the cure of many diseases, like tumors. This treatment uses a combination of light and a photosensitive molecule in the presence of oxygen. In this way, our objective is to understand photosensibilization mechanisms on membranes. For this purpose, we studied the effects of irradiation in Giant Unilamelar Vesicles (GUVs) composed of POPC and Cardiolipin (CL) and POPC and Cholesterol (Chol) in the presence of a photosensitive molecule (diC12-porf). When the GUVs composed of POPC or POPC and Cholesterol (Chol) in the presence of the photosensitive molecule were irradiated, increase in surface area followed by fluctuations was observed. For GUVs composed of low concentrations of CL, the membrane photo-response was similar to that observed for pure POPC. For GUVs composed of 50 mol% CL different responses to light irradiation were observed. Some lipid domains appear for GUVs in water under irradiation and the GUV might be destroyed. When the irradiation was done in the presence of EDTA (chelant agent), the formation of the domains was prevented. Further addition of CaCl2 to this solution induced the formation of domains again leading eventually to membrane disruption. These results suggest that divalent cations have effect on the binding to CL negative polar heads, favoring lipid domain formation. We quantified the area increase obtained for the GUVs. For GUVs composed of CL we observed that until 40mol% of CL, the maximum expansion reached by the membrane area was similar to that obtained for pure POPC. For 50mol% of CL the increase of area is smaller than that found for GUVs composed only by POPC. For GUVs composed of Chol the behavior of the area is similar to that found for POPC. This means that the increase of area is mainly related to POPC peroxidation, although Chol hydroperoxide must be concomitantly formed too. Further, we observed that the diC12-porf photobleaching characteristic time for GUVs composed of CL/Chol is greater than that noted for GUVs composed of POPC. This means that when we introduce CL we are increasing the possibilities of reaction of the singlet oxygen and the photosensitive molecule is protected. The insertion of Chol in the membrane also protects the photosensitive molecule.

A Terapia Fotodinâmica é um tratamento promissor no cura de várias doenças oftalmológicas e dermatológicas, assim como tumores. Este tratamento utiliza a combinação de luz e um composto fotossensível na presença de oxigênio. Neste trabalho objetivamos entender mecanismos de fotossensibilização em membranas. Para isso, estudamos os efeitos de irradiação em Vesículas Unilamelares Gigantes (GUVs) compostas de POPC e Cardiolipina (CL) e POPC e Colesterol (Col), contendo uma molécula fotoativa (diC12-porf) ancorada à superfície dessas membranas. GUVs compostas por POPC e POPC:Col na presença da molécula fotoativa reagem ao estímulo da luz exibindo um aumento de área seguido de flutuações. O mesmo foi observado para membranas de POPC contendo menos que 50mol% de CL. Já para composições contendo 50mol% de CL, a membrana passa a formar domínios lipídicos podendo ou não ser destruída durante a irradiação. Estes domínios podem ser suprimidos com a adição de EDTA (agente quelante de íons divalentes) na solução. Ao adicionarmos CaCl2 ao meio externo das GUVs contendo EDTA, percebemos que o efeito dos domínios e destruição da membrana reaparece. Tal fato evidencia que íons Ca++ presentes em solução devem complexar com as cargas da CL, levando à formação de domínios lipídicos. Ao quantificar o aumento de área sofrido pelas membranas percebemos que a presença de CL na membrana de POPC inibe o aumento de área para concentrações acima de 40mol% de CL. Já a presença de Col na membrana parece não contribuir significativamente para o aumento de área, embora o mesmo sofra oxidação. Além disso, evidenciou-se que na presença de CL/Col o tempo de fotoclareamento de diC12-porf é muito maior do que na ausência destes. Estes resultados evidenciam que a inclusão de CL na membrana oferece um número maior de sítios de reação para o oxigênio singlete reduzindo a foto-degradação da molécula fotoativa. Já a inclusão de Col aumenta o tempo de vida da molécula fotoativa provavelmente devido ao fato da dupla ligação do Col estar mais próxima ao centro produtor de oxigênio singlete do que a dupla ligação do POPC. / Photodynamic Therapy is a promising treatment for the cure of many diseases, like tumors. This treatment uses a combination of light and a photosensitive molecule in the presence of oxygen. In this way, our objective is to understand photosensibilization mechanisms on membranes. For this purpose, we studied the effects of irradiation in Giant Unilamelar Vesicles (GUVs) composed of POPC and Cardiolipin (CL) and POPC and Cholesterol (Chol) in the presence of a photosensitive molecule (diC12-porf). When the GUVs composed of POPC or POPC and Cholesterol (Chol) in the presence of the photosensitive molecule were irradiated, increase in surface area followed by fluctuations was observed. For GUVs composed of low concentrations of CL, the membrane photo-response was similar to that observed for pure POPC. For GUVs composed of 50 mol% CL different responses to light irradiation were observed. Some lipid domains appear for GUVs in water under irradiation and the GUV might be destroyed. When the irradiation was done in the presence of EDTA (chelant agent), the formation of the domains was prevented. Further addition of CaCl2 to this solution induced the formation of domains again leading eventually to membrane disruption. These results suggest that divalent cations have effect on the binding to CL negative polar heads, favoring lipid domain formation. We quantified the area increase obtained for the GUVs. For GUVs composed of CL we observed that until 40mol% of CL, the maximum expansion reached by the membrane area was similar to that obtained for pure POPC. For 50mol% of CL the increase of area is smaller than that found for GUVs composed only by POPC. For GUVs composed of Chol the behavior of the area is similar to that found for POPC. This means that the increase of area is mainly related to POPC peroxidation, although Chol hydroperoxide must be concomitantly formed too. Further, we observed that the diC12-porf photobleaching characteristic time for GUVs composed of CL/Chol is greater than that noted for GUVs composed of POPC. This means that when we introduce CL we are increasing the possibilities of reaction of the singlet oxygen and the photosensitive molecule is protected. The insertion of Chol in the membrane also protects the photosensitive molecule.

La construction de nouvelles architectures d'aimant moléculaire basé sur l'approche métal-radical repose sur la conception de nouvelles molécules radicalaires. Dans cette optique, notre stratégie s'est concentrée sur la synthèse de porphyrins incorporant des composés radicaux libres. En effet, les porphyrines sont des composés π conjugués qui devraient favoriser la délocalisation de spin et la transmission des interactions magnétiques sur l'entier macrocycle et de plus sur l'ensemble du composé obtenu. A cause de leur excellente stabilité dans une grande diversité d'environnements chimiques et leur capacité à coordonner avec des métaux de transitions, notre choix s'est porté sur les radicaux nitroxides. Dans cette thèse, une série de porphyrines contenant des tBUNO, nitronyl and imino nitroxide directement liés sur le squelette de la molécule ont été synthétisées. Les macrocycles obtenus ont été caractérisés par UV-Vis, Masse et RPE spectroscopie. De plus, durant ce travail, des intermédiaires réactionnaires intéressant ont été obtenus et caractérisés pour la première fois. Ce fut le cas pour la meso-tetrakis(4-formylphenyl)porphyrin et ses équivalents métallés pa le Cu(II) et le Mn(II). Ainsi que pour quelques précurseurs prometteurs de macrocycle tetrapyrroliques comme 2-(3,4-dicyanophenyl)-4,4,5,5-tetramethylimidazoline-3-oxide-1oxyl, 2-(3,4-dicyanophenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl and 2-(4-benzaldehyde)-4,4,5,5-tetramethylimidazoline-1-oxyl. D'après ce que nous savons, ces composés représentent le premier exemple de porphyrines substituées par des nitronyl et imino nitroxide radical, ayant été caractérisées sans ambiguïté par des méthodes spectroscopiques / The preparation of Molecule-Based Magnets is based on the assembling carriers of magnetic moment. These may be the metal ions only with diamagnetic linkers or the metal ions connected through open-shell organic molecule. The building of novel Molecule-Based Magnets architectures following the metal-radical approach relies on the design of innovative open-shell organic molecular blocks. In this regard, we focus our strategy on the synthesis of porphyrins incorporating free radicals. Indeed, porphyrins compounds are π-conjugated systems which should favor spin delocalization and the transmission of the magnetic interactions on the overall macrocycle and further over the all architecture. Due to their excellent stability in a wide variety of chemical environments, and their abilities to coordinate with transition metal we focus our attention on nitroxide radicals. In this dissertation a series of porpyrin macrocycles were synthesized, bearing tBuNO, nitronyl and imino nitroxide covalently linked to the skeleton. Characterization was done by UV-Vis, Mass and EPR spectroscopy. Moreover during this work some interesting synthetic intermediates were obtained with good yield and characterize for the first time. This was the case for meso-tetrakis(4-formylphenyl)porphyrin and its corresponding metallated derivatives by Cu(II) and Mn(II). Some novel promising tetrapyrrolic macrocycle precursors bearing nitronyl and imino nitroxides free radicals as 2-(3,4- dicyanophenyl)-4,4,5,5-tetramethylimidazoline-3-oxide-1-oxyl, 2-(3,4- dicyanophenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl and 2-(4-benzaldehyde)-4, 4, 5, 5-tetramethylimidazoline-1-oxyl. To the best of our knowledge, these compounds represent the first example of nitronyl and imino nitroxide substituted porphyrin derivatives that have been unambiguously characterized by spectroscopic techniques