No description available.

No description available.

<p> Photodynamic therapy (PDn is an effective treatment option for various types of invasive tumors, the efficacy of which depends strongly on selective cell uptake and selective excitation of the tumor, which relies on proper dosage. The characterization of the fluorescence lifetimes of photosensitizers localized inside living cells may provide the basis for further investigation of in vitro PDT dosage measurements using time-domain spectroscopy and imaging. In this thesis, the fluorescence lifetimes of localized Photofrin ® and delta-aminolevulinic acid (ALA) induced protoporphyrin IX (PpiX) were investigated in living MAT-LyLu (MLL) rat prostate adenocarcinoma cells. Cells were incubated with the photosensitizers, and then treated with light under well-oxygenated conditions using a two-photon fluorescence lifetime imaging microscope (FLIM). Fluorescence lifetime images of these cells were recorded with average lifetimes of 5.5 ± 1.2 ns for Photofrin and 6.3 ± 1.2 ns for ALA-induced PpiX over 600 to 750 nm. Two channel FLIM revealed lifetimes of7.8 ± 0.5 ns for Photofrin® and 10.8 ± 1.7 ns for PpiX over 620 to 645 nm, while photoproducts observed on the second channel yielded lifetimes of 5.1 ± 0.4 ns over 650 to 670 nm for Photofrin® and 6.3 ± 1.0 ns over 670 to 690 nm for PpiX. Fluorescence lifetimes of both photosensitizers were found to be significantly shorter when localized in cells than when measured in solutions, suggesting that photosensitizers' lifetimes go through significant changes when bonded to intracellular components. These changes in lifetime also provide opportunities to quantitatively measure and monitor the binding states of the photosensitizers and their microenvironment, which may be used in real-time PDT dosimetry, as well as for diagnostic purposes. </p> / Thesis / Master of Applied Science (MASc)

Zinc dipyrrin complexes have the potential to act as cheap, effective photosensitizers. Synthesizing and studying different types could lead to more efficient solar energy harvesting processes, especially the production of solar fuel. Here, two attempts to synthesize 1,3,7,9-tetraphenyl-5-mesityldipyrromethene are reported and discussed. According to 1H NMR, the first synthesis attempt was not successful. The second synthesis attempt was not purified effectively, so 1H NMR produced inconclusive results. Further purification strategies or alternate synthesis methods are required.

No description available.

No description available.

Este trabalho tem por objetivo investigar o comportamento da terapia fotodinâmica (PDT) em leveduras patogênicas. Tem sido proposto que a PDT pode inativar células microbianas e, um grande número de fotossensibilizadores e fontes de irradiação são reportados em diferentes parâmetros. Para melhor entendimento dos processos fotodinâmicos, a taxa de fluência, fluência e tempo de irradiação foram estudadas, bem como fluências iguais em parâmetros diferentes foram comparadas entre si. O papel da concentração de azul de metileno e do transporte desta droga pela membrana fúngica foram investigados. Diferentes cepas de Cryptococcus neoformans foram comparadas frente à ação fotodinâmica com fotossensibilizadores distintos. Após esta etapa, atividades metabólicas de processo de morte microbiana e produção de melanina foram avaliadas quanto a sua interferência na inativação fúngica. Por fim, um modelo de criptococose foi desenvolvido para avaliação in vivo da ação fotodinâmica. Foi observado que parâmetros de irradiação influenciam substancialmente os resultados da PDT em leveduras e que, fluências iguais em diferentes tempos de irradiação podem apresentar resultados diferentes. Em conclusão, a fluência não deve ser utilizada como parâmetro único para comparação dos resultados de fotoinativação de leveduras. Além disso, o transporte de azul de metileno pela membrana fúngica pode influenciar os efeitos da PDT. A ação fotodinâmica depende do sítio de ligação do fotossensibilizador na célula e não somente da quantidade de moléculas no interior do microrganismo. É importante ressaltar que características intrínsecas de cada cepa podem influenciar diretamente os efeitos da PDT. As células morrem geralmente por processo não lítico, e quando utilizada in vivo, a PDT mostrou-se capaz de reduzir a recuperação de células viáveis. / This study aimed to investigate the photodynamic therapy (PDT) behavior on pathogenic yeasts. It has been proposed in literature that PDT is able to inactivate microbial cells, and a number of photosensitizer (FS) agents and irradiation sources were reported with different parameters. The role of fluence rate, as well as fluence and irradiation time was studied to achieve a deep understanding of this subject and to compare equivalent fluences under dissimilar irradiation parameters. Methylene blue concentration and its transport through yeast membrane were also focused. Cryptococcus neoformans strains that present particular metabolic characteristics were used to investigate photosensitizers and their ability to inactivate yeast. Furthermore, the role of PDT in microbial death process and inhibition of killing effects by melanin production were analyzed. Thereafter, an in vivo model of cryptococcosis was developed to evaluate photodynamic effect. The main point of our results was that light parameters play an important role on yeast inactivation and the same fluence under different irradiation parameters present dissimilar quantity of cell death. In conclusion, fluence per se should not be used as the only parameter to compare photoinactivation effects on yeast cells. In addition, MB transport thought yeast membrane can change PDT effects, as well as the photosensitizer preferential bind site inside the cell. The quantity of PS uptake, under specific conditions, does not seem to present a direct relation with cell inactivation. In addition, microbial strain characteristics can directly interfere on PDT results and cells appear to be killed by an apoptotic-like effect. Finally, PDT can kill C. neoformans in vivo and reduces its recover from infected site.

Este trabalho tem por objetivo investigar o comportamento da terapia fotodinâmica (PDT) em leveduras patogênicas. Tem sido proposto que a PDT pode inativar células microbianas e, um grande número de fotossensibilizadores e fontes de irradiação são reportados em diferentes parâmetros. Para melhor entendimento dos processos fotodinâmicos, a taxa de fluência, fluência e tempo de irradiação foram estudadas, bem como fluências iguais em parâmetros diferentes foram comparadas entre si. O papel da concentração de azul de metileno e do transporte desta droga pela membrana fúngica foram investigados. Diferentes cepas de Cryptococcus neoformans foram comparadas frente à ação fotodinâmica com fotossensibilizadores distintos. Após esta etapa, atividades metabólicas de processo de morte microbiana e produção de melanina foram avaliadas quanto a sua interferência na inativação fúngica. Por fim, um modelo de criptococose foi desenvolvido para avaliação in vivo da ação fotodinâmica. Foi observado que parâmetros de irradiação influenciam substancialmente os resultados da PDT em leveduras e que, fluências iguais em diferentes tempos de irradiação podem apresentar resultados diferentes. Em conclusão, a fluência não deve ser utilizada como parâmetro único para comparação dos resultados de fotoinativação de leveduras. Além disso, o transporte de azul de metileno pela membrana fúngica pode influenciar os efeitos da PDT. A ação fotodinâmica depende do sítio de ligação do fotossensibilizador na célula e não somente da quantidade de moléculas no interior do microrganismo. É importante ressaltar que características intrínsecas de cada cepa podem influenciar diretamente os efeitos da PDT. As células morrem geralmente por processo não lítico, e quando utilizada in vivo, a PDT mostrou-se capaz de reduzir a recuperação de células viáveis. / This study aimed to investigate the photodynamic therapy (PDT) behavior on pathogenic yeasts. It has been proposed in literature that PDT is able to inactivate microbial cells, and a number of photosensitizer (FS) agents and irradiation sources were reported with different parameters. The role of fluence rate, as well as fluence and irradiation time was studied to achieve a deep understanding of this subject and to compare equivalent fluences under dissimilar irradiation parameters. Methylene blue concentration and its transport through yeast membrane were also focused. Cryptococcus neoformans strains that present particular metabolic characteristics were used to investigate photosensitizers and their ability to inactivate yeast. Furthermore, the role of PDT in microbial death process and inhibition of killing effects by melanin production were analyzed. Thereafter, an in vivo model of cryptococcosis was developed to evaluate photodynamic effect. The main point of our results was that light parameters play an important role on yeast inactivation and the same fluence under different irradiation parameters present dissimilar quantity of cell death. In conclusion, fluence per se should not be used as the only parameter to compare photoinactivation effects on yeast cells. In addition, MB transport thought yeast membrane can change PDT effects, as well as the photosensitizer preferential bind site inside the cell. The quantity of PS uptake, under specific conditions, does not seem to present a direct relation with cell inactivation. In addition, microbial strain characteristics can directly interfere on PDT results and cells appear to be killed by an apoptotic-like effect. Finally, PDT can kill C. neoformans in vivo and reduces its recover from infected site.

Ce travail concerne le développement de nanoparticules de TiO2 et de SiO2 sensibilisées aux photosensibilisateurs pour application dans la photocatalyse et la thérapie photodynamique (PDT). Les NP ont été soit recouverts d'une coquille de polysiloxane, soit modifiés par l'aminopropyltriéthoxysilane (APTES) seul. Les PSs de tétraphényl monocarboxylphosphine (P1-COOH) ou de chlorine e6 (Ce6) ont été couplés aux NP par liaison amide. En photocatalyse, les NP hybrides modifiées par l'APTES, en particulier TiO2-APTES-Ce6, présentent une activité photocatalytique supérieure vis-à-vis de la dégradation du bleu de méthylène et de l’orange de méthyle sur les systèmes cœur-coquille sous lumière solaire et visible. Pour la PDT, des tests in vitro ont été désignés sur la lignée cellulaire de glioblastome U87 à différentes concentrations de NP éclairées à 652 nm. TiO2-APTES-Ce6 a révélé une bonne phototoxicité car la viabilité cellulaire a diminué de 89% après illumination. L'incorporation cellulaire et la localisation de ces NP et de leurs analogues de la silice ont été explorées. Les ROS impliqués dans la photocatalyse et la PDT ont été étudiés / This work addresses the development of dye-sensitized TiO2 and SiO2 nanoparticles (NPs) for application in photocatalysis and photodynamic therapy (PDT). The NPs were either coated with a polysiloxane shell or modified by aminopropyl triethoxysilane (APTES) alone. Monocarboxylic tetraphenyl porphyrin (P1-COOH) or chlorin e6 (Ce6) PSs were coupled to the NPs by amide bond. In photocatalysis, The APTES-modified sensitized NPs, particularly TiO2-APTES-Ce6, exhibit a superior activity towards the degradation of methylene blue and methyl orange over the core-shell systems under solar and visible light. For PDT, in vitro tests were conducted on the glioblastoma cell line U87 at different NPs’ concentrations illuminated at 652 nm. TiO2-APTES-Ce6 revealed a good phototoxicity as the cell viability decreased by 89% after illumination. The cellular uptake and localization of those NPs and their silica analogues were explored. The ROS involved in photocatalysis and PDT were investigated

Photocatalytic carbon dioxide reduction transforms CO2 to useful chemicals and fuels, reducing CO2 emissions and making fossil fuels more renewable. Due to a lack of earthabundant sensitizers, we want to design new earth-abundant sensitizers to go with the many known carbon dioxide reduction catalysts. Zn(II) dipyrrin complexes strongly absorb visible light, but their excited state properties have not been widely studied. To investigate their photophysical properties, two Zn dipyrrin complexes, with and without heavy atoms, were synthesized and characterized by NMR and mass spectrometry. The photophysical properties of the two complexes were measured in polar and non-polar solvents, particularly fluorescence quantum yield and extinction coefficient. Also, through transient absorption spectroscopy, the triplet state quantum yield of both complexes was measures to determine the effect of solvent polarity and heavy atoms on the triplet state formation.