Porphyrins represent one of the oldest, most widely studied chemical structures, both in nature and in biomedical applications. Due to their tumor avidity and favorable photophysical properties, such as long wavelength absorption and emission, easy derivatization, high singlet oxygen quantum yield and low in vivo toxicity, porphyrins have found particular success for photodynamic therapy and fluorescence imaging of cancer. Additionally, they are excellent metal chelators, forming highly stable metallo-complexes, making porphyrins an efficient delivery vehicle for radioisotopes. Thus, there is great potential in the applications of these multi-modal porphyrin-based agents for cancer imaging and therapy. I have investigated the characteristics of various porphyrin-based probes and their potential application in different clinically relevant models. Here, I will discuss three types of porphyrin-based agents: 1) photodynamic molecular beacons (PPMMPB), 2) targeted peptide porphyrins (PPF) and 3) porphyrin-lipid nanovesicles, porphysomes. I will demonstrate that all of these porphyrin-based agents have potential clinical applications in various fields of cancer imaging and therapy. Although these three agents differ greatly, they all aim to increase the signal-to-background ratio of tumor to healthy tissue uptake of porphyrins, thereby increasing our ability to detect tumor tissue and better preserve healthy tissue during therapy.

Porphyrins represent one of the oldest, most widely studied chemical structures, both in nature and in biomedical applications. Due to their tumor avidity and favorable photophysical properties, such as long wavelength absorption and emission, easy derivatization, high singlet oxygen quantum yield and low in vivo toxicity, porphyrins have found particular success for photodynamic therapy and fluorescence imaging of cancer. Additionally, they are excellent metal chelators, forming highly stable metallo-complexes, making porphyrins an efficient delivery vehicle for radioisotopes. Thus, there is great potential in the applications of these multi-modal porphyrin-based agents for cancer imaging and therapy. I have investigated the characteristics of various porphyrin-based probes and their potential application in different clinically relevant models. Here, I will discuss three types of porphyrin-based agents: 1) photodynamic molecular beacons (PPMMPB), 2) targeted peptide porphyrins (PPF) and 3) porphyrin-lipid nanovesicles, porphysomes. I will demonstrate that all of these porphyrin-based agents have potential clinical applications in various fields of cancer imaging and therapy. Although these three agents differ greatly, they all aim to increase the signal-to-background ratio of tumor to healthy tissue uptake of porphyrins, thereby increasing our ability to detect tumor tissue and better preserve healthy tissue during therapy.

Photodynamic therapy has been established as one of the approaches for the treatment of various malignant tumors. While most of the reagents used for this purpose are porphyrin derivatives, there is a strong motivation for finding novel and better sensitizers. Perylenediimides are known for their photo- and chemical stability, but they do not have absorptions in the red end of the visible spectrum. However, recently reported green perylenediimides which have dialkylamino substituents on the perylene core, provide an alternative. To that end, we have designed and synthesized novel green perylenediimides with remarkable water solubility at neutral pH and absorption peaks beyond 650 nm. We demonstrated that on red-light excitation, singlet oxygen trap 1,3-diphenyl-iso-benzofuran is rapidly degraded. We also carried out cell culture experiments / an important parameter to be optimized for practical application as a novel photodynamic therapy agent was the excited dye toxicity to dark toxicity. Our results confirmed that these novel perylenediimides acted as sensitizers generating singlet oxygen and the initial in vitro biological experiments demonstrated their potential utility in photodynamic therapy.

Submitted by Ligia Souza (ligia@ufscar.br) on 2017-09-21T14:27:46Z No. of bitstreams: 1 TeseMCG.pdf: 3682312 bytes, checksum: fd17a7f18e76507395baaaf315348805 (MD5) / Approved for entry into archive by Ronildo Prado (ronisp@ufscar.br) on 2017-09-25T12:32:38Z (GMT) No. of bitstreams: 1 TeseMCG.pdf: 3682312 bytes, checksum: fd17a7f18e76507395baaaf315348805 (MD5) / Approved for entry into archive by Ronildo Prado (ronisp@ufscar.br) on 2017-09-25T12:32:44Z (GMT) No. of bitstreams: 1 TeseMCG.pdf: 3682312 bytes, checksum: fd17a7f18e76507395baaaf315348805 (MD5) / Made available in DSpace on 2017-09-25T12:37:57Z (GMT). No. of bitstreams: 1 TeseMCG.pdf: 3682312 bytes, checksum: fd17a7f18e76507395baaaf315348805 (MD5) Previous issue date: 2017-07-31 / Outra / Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / Infectious pneumonia is a major cause of morbidity/mortality, mainly due to the increasing rate of microorganisms resistant to antibiotics. Photodynamic Inactivation (PDI) is emerging as a promising approach, as effects are based on oxidative stress, preventing the emergence of resistant microorganism strains. In previous studies, the in vitro inactivation of Streptococcus pneumoniae using indocyanine green (ICG) and infrared light source was successful, and achieved reduction of 5 log10 colony-forming units (CFU/mL) with concentration as low as 10 μM ICG. In the present study, a proof-of-principle protocol was designed to treat lung infections by PDI using extracorporeal illumination with a 780 nm laser device and ICG as photosensitizer. In a first row of experiments, hairless mice were infected with S. pneumoniae and PDI was performed two days after infection. For control groups, CFU recovery ranged between 103-104 CFU/mL/mouse. For PDT group, however, no bacteria were recovered in 80% of the animals. Animal survival was evaluated separately over 50 days. No deaths occurred in PDT group, whereas 60% of the control did not survive. Lung injury analyses were performed in BALB/c mice, the bacteria reduction were 2 and 4 log10 in 2 mice (5 in total) and the wet-to-dry ratio showed that PDI did not increase the edema in lungs. The bronchoalveolar lavage data indicated a larger absolute number of cells (mononuclear and polymorphonuclear) in the PDI group in contrast to control group, meaning that the technique could increase the immune system response. In vitro results showed the irradiated ICG could generate aggregates or photoproducts that help PDI to inactivate the bacteria. Our results indicate that extracorporeal PDI has potential for pneumonia treatment, and pulmonary decontamination with PDI may be used as a single therapy or as an antibiotics adjuvant. / A pneumonia infecciosa é uma das principais causas de morbidade/mortalidade no mundo, principalmente devido à taxa crescente de micro-organismos resistentes a antibióticos. A inativação fotodinâmica (IFD) está emergindo como uma abordagem promissora, cujos efeitos são baseados no estresse oxidativo, impedindo o surgimento de cepas de micro-organismos resistentes. Em estudos anteriores, a inativação in vitro de Streptococcus pneumoniae utilizando indocianina verde (ICV) e fonte de luz de infravermelho foi efetiva, inativando 5 log10 (UFC/mL) com apenas 10 μM ICV. Neste estudo, foi avaliado protocolo de prova de princípio para tratar infecções pulmonares por IFD usando irradiação extracorpórea com dispositivo a laser emitindo em 780 nm e ICV como fotossensibilizador (FS). Em uma primeira série de experimentos, camundongos hairless SKH-1 foram infectados com S. pneumoniae e a IFD foi realizada dois dias após a infecção. Para os grupos de controles, a recuperação de UFC variou entre 103-104 UFC/mL/animal. Para o grupo IFD, no entanto, nenhuma bactéria foi recuperada em 80% dos animais. A sobrevivência animal foi avaliada durante 50 dias. Não ocorreram mortes no grupo IFD, enquanto 60% do grupo controle foi a óbito. Foram realizadas análises de lesões pulmonares em camundongos BALB/c, onde a redução bacteriana foi de 2 e 4 log10 em dois animais (total 5) em comparação com o grupo controle, e a proporção de peso úmido e seco mostrou que a IFD não aumentou o edema nos pulmões. Os dados de lavagem broncoalveolar indicaram um aumento no número absoluto de células (mononucleares e polimorfonucleares) no grupo IFD, o que indica que a técnica pode aumentar a resposta do sistema imunológico. Os resultados in vitro mostraram que a ICV irradiada pode gerar agregados ou fotoprodutos que auxiliam a IFD a inativar a bactéria. Os resultados deste estudo indicam que a IFD com irradiação extracorpórea tem potencial para o tratamento de pneumonia, e a descontaminação pulmonar com IFD pode ser usada como terapia ou como adjuvante aos antibióticos. / CAPES: 99999.003154/2015-07

Made available in DSpace on 2015-05-14T12:56:09Z (GMT). No. of bitstreams: 1 arquivototal.pdf: 910904 bytes, checksum: c726c0e05bf38f910085210325321242 (MD5) Previous issue date: 2010-08-19 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Candida species are part of the commensal microbiota of the oral cavity of most healthy individuals. The emergence of new species of Candida and the selection of lines tolerant to conventional antifungal agents stimulates the development of new therapies for the treatment of infections caused by species of Candida. In this context stands the photodynamic therapy (PDT) which is capable of killing fungal cells by administration of a photosensitizing substance followed by the application of light in the visible wavelength. This study evaluated, in vitro, the efficacy of PDT in photoinactivation of Candida species (C. albicans, C. krusei, C. tropicalis and C. guilhermondii) using the photosensitizing agent methylene blue (150&#956;g/ml) and irradiation with a diode laser operating in the visible red (&#654;660nm, 40mW). Initially, the tested microorganisms were inoculated in test tubes containing liquid culture medium and incubated overnight at 37°C. Then cell s uspensions were obtained containing 106 cfu / ml. These suspensions were transferred to 96-holes plates and exposed to 03 doses of laser light (Group 1- 60J/cm2 (2,4J), Group 2- 120J/cm2 (4,8J), Group 3-180J/cm2 (7,2J)). Additional suspensions were treated with only the photosensitizer, with only the laser light or with 0.85% saline (control group). Each experimental condition was performed twice. After the treatments, 1&#956;l aliquots of the suspensions were plated on Sabouraud Dextrose Agar. The plates were incubated at 37°C for 24-48h and after this period there was the counting of colonies (cfu / ml). The three doses evaluated determined significant inactivation of Candida spp. (P <0.05). The 180J/cm2 dose was the most effective, inactivating 78% of cfu/ml followed by doses of 120J/ cm2 and 60J/cm2 with inactivation average of 62% and 42% respectively. A statistically significant difference between the rates of inactivation of C. albicans, C.krusei, C. tropicalis and C. guilhermomdii at doses of 60 J/cm2 and 120 J/cm2 (p> 0.05) was not verified. However, at a dose of 180 J/cm2 C. albicans was the most susceptible species to the effects of PDT. We conclude that photodynamic therapy (PDT) has demonstrated effectiveness in the inactivation of Candida spp. / As espécies de Candida fazem parte da microbiota comensal da cavidade bucal da maioria dos indivíduos saudáveis.. A emergência de novas espécies de Candida e a seleção de linhagens tolerantes aos antifúngicos convencionais estimula o desenvolvimento de novas modalidades terapêuticas para o tratamento das infecções causadas por espécies de Candida.Nesse contexto destaca-se a terapia fotodinâmica (TFD) que é capaz de eliminar células fúngicas através da administração de uma substância fotosensibilizadora seguido da aplicação de luz em comprimento de onda visível e compatível. Este estudo avaliou, in vitro, a eficácia da TFD na fotoinativação de espécies do gênero Candida (C. albicans, C. krusei, C. tropicalis e C. guilhermondii) por meio do agente fotossensibilizador azul de metileno (150&#956;g/ml) e da irradiação com um Diodo Laser (660nm, 40mW)). Inicialmente os microrganismos avaliados foram inoculados em tubos de ensaio contendo meio de cultura líquido e incubados overnight a 37°C. Em seguida foram obtidas suspensões celulares contendo 106 ufc/ml, as quais foram transferidas para placas de 96 orifícios e expostas a 03 doses de luz Laser (Grupo1- 60J/cm2 (2,4J), Grupo2- 120J/cm2 (4,8J), Grupo 3-180J/cm2 (7,2J). Suspensões adicionais foram tratadas apenas com o fotossensibilizador, apenas com a luz Laser ou com solução salina 0,85% (grupos controle). Cada condição experimental foi realizada 2 vezes. Após a aplicação dos tratamentos, alíquotas de 1&#956;l das suspensões foram plaqueadas em Agar Sabouraud Dextrose. As placas foram incubadas a 37°C por 24-48h e após esse período foi realizada a contagem das colônias (ufc/ml). As três doses avaliadas determinaram inativação significativa de Candida spp. (p<0,05). A dose de 180J/cm2 foi a mais eficaz, inativando 78% das ufc seguida pelas doses de 120J/ cm2 e 60J/cm2 com inativação média de 62% e 42% respectivamente. Não foi verificada diferença estatística significativa entre as taxas de inativação de C.albicans, C.krusei, C. tropicalis e C. guilhermomdii nas doses de 60 J/cm2 e 120 J/cm2 (p> 0,05). No entanto, na dose de 180 J/cm2 C. albicans foi a espécie mais susceptível aos efeitos da TFD. Conclui-se que a terapia fotodinâmica (PDT) demonstrou efetividade na inativação de Candida spp.

O objetivo deste estudo foi avaliar o efeito antibacteriano e a dissolução de biofilme promovido pela terapia fotodinâmica (PDT) associada com o hipoclorito de sódio (NaOCl) 2,5% e a clorexidina (CHX) sobre biofilmes mono-espécie e multi-espécies. No modelo de biofilme mono-espécie, quarenta e seis prémolares inferiores foram contaminados com cepas de Enterococcus faecalis (ATCCC 29212) por 21 dias. Os espécimes foram divididos em três grupos de acordo com a solução irrigadora utilizada: soro fisiológico, CHX 2% e NaOCl 2,5%. Após irrigação com 5 mL de cada irrigante, a PDT foi realizada. Amostras foram coletadas previamente aos protocolos de irrigação (S1), após irrigação (S2) e após PDT (S3). No modelo de biofilme multi-espécies, sessenta blocos de dentina bovina foram infectados intraoral e divididos em seis grupos: soro fisiológico, soro fisiológico/PDT, CHX, CHX/PDT, NaOCl e NaOCl/PDT. Microscopia confocal a laser foi usada para avaliar a porcentagem e o biovolume de células vivas e o volume total de biofilme. Todos os grupos reduziram as contagens de UFCs após os procedimentos de irrigação (S1-S2); porém a CHX e o NaOCl promoveram as menores contagens de UFCs (P < 0,05). A PDT diminuiu significativamente a contagem bacteriana no grupo do soro fisiológico (S2-S3; P < 0,05). No modelo de biofilme multi-espécies, a menor quantidade de células vivas foi observada nos grupos CHX, CHX/PDT, NaOCl e NaOCl/PDT, sem diferenças entre si (P > 0,05). A PDT não reduziu o volume total de biofilme (P > 0,05); porém parece diminuir o biovolume e a quantidade de células vivas após irrigação com CHX 2% e NaOCl 2,5%. A terapia fotodinâmica associada ao soro fisiológico reduziu a carga bacteriana em canais infectados com E. faecalis. A PDT parece reduzir a quantidade e o volume de células vivas, mas não o volume total de células em biofilme multiespécies induzido in situ. Finalmente, o tipo de irrigante foi decisivo para dissolver biofilme multi-espécies. / The aim of this study was to evaluate the antibacterial effect and the biofilm dissolution promoted by photodynamic therapy (PDT) associated with 2.5% NaOCl and 2% CHX over monospecies and multispecies biofilms. In monospecies biofilm model, forty-six mandibular premolars were contaminated with Enterococcus faecalis strains (ATCC 29212) broth culture for 21 days. Specimens were divided into three groups according to the irrigant used: saline, 2% of CHX and 2.5% of NaOCl. After irrigation with 5 mL of each irrigant, PDT was performed. Samples were collected at baseline (S1), after irrigation (S2) and after PDT (S3). In multispecies biofilm model, sixty bovine dentin blocs were infected intraorally, and divided into six groups: saline, saline/PDT, CHX, CHX/PDT, NaOCl and NaOCl/PDT. Confocal laser scanning microscopy was used to assess the percentage and the biovolume of live cells and the total biovolume. All groups reduced UFC’ counts after irrigation procedures (S1-S2); however CHX and NaOCl promoted the lowest UFCs counts (P < 0.05). PDT significantly reduced the bacterial counts in saline group (S2-S3; P < 0.05). In multispecies biofilm model, the lowest amount of live cells was observed in CHX, CHX/PDT, NaOCl and NaOCl/PDT groups, with no differences among them (P > 0.05). PDT did not reduce the total biovolume (P > 0.05); however it appears to decrease the biovolume and the amount of live cells after irrigation with 2% CHX and 2.5% NaOCl. PDT associated with saline reduced the bacterial load in canal infected with E. faecalis. PDT seems to reduce the amount and the biovolume of live cells, but did not reduce the total biovolume of cells in multispecies biofilm induced in situ. Finally, the irrigant was decisive to dissolve multispecies biofilm.

Submitted by Ana Maria Fiscina Sampaio (fiscina@bahia.fiocruz.br) on 2015-09-29T16:35:13Z No. of bitstreams: 1 Anderson F. Suzart Miranda ...2015.pdf: 1366998 bytes, checksum: 77aaca114530e82c696b0330413431a9 (MD5) / Approved for entry into archive by Ana Maria Fiscina Sampaio (fiscina@bahia.fiocruz.br) on 2015-09-29T16:35:44Z (GMT) No. of bitstreams: 1 Anderson F. Suzart Miranda ...2015.pdf: 1366998 bytes, checksum: 77aaca114530e82c696b0330413431a9 (MD5) / Made available in DSpace on 2015-09-29T16:35:45Z (GMT). No. of bitstreams: 1 Anderson F. Suzart Miranda ...2015.pdf: 1366998 bytes, checksum: 77aaca114530e82c696b0330413431a9 (MD5) Previous issue date: 2015 / Fundação Oswaldo Cruz. Centro de Pesquisas Gonçalo Moniz. Salvador, BA, Brasil / O câncer é considerado a segunda maior causa de morte em países ocidentais. Nos Estados Unidos da América (EUA) as mortes por câncer anualmente superam a soma das mortes provocadas em guerras como Vietnã, Coreia e as Grandes Guerras Mundiais. Apresentando-se como a mais agressiva das neoplasias dermatológicas, o melanoma cutâneo está associado à cerca de 75% das causas de morte por câncer de pele. Um dos tratamentos estudados para aplicação em pacientes com esta e outras patologias é a Terapia Fotodinâmica (TFD), que é baseada no uso de corantes de baixa toxicidade, que tem seletividade por alguns tecidos ou células e quando ativados por baixas doses de luz visível induzam alterações celulares como a produção ERO. Os fenotiazínicos são moléculas catiônicas com, absorção de luz na região entre 620-660nm, espectro que permite maior penetração nos tecidos, promovendo maior ação do composto em tecidos mais profundos. A irradiação foi feita com luz lazer com λ= 660nm, com potência de 100 mW, densidade de energia de 150 J/cm2 por 1 min. As quantificações de viabilidade celular foram feitas por método colorimétrico, e realizada a leitura em leitor de microplaca a 655 nm. A determinação das IC50 do Azul de Metileno e Azul de Toluidina O foi 2,5 μM e 8,4 μM, respectivamente. Utilizando a TFD observamos que os efeitos citotóxicos dos compostos fenotiazínicos apresentam significância estatística (p<0,05) tanto em AM quanto em ATO. Em microscopia óptica com coloração por May-Grunwald-Giemsa observamos que existe uma aparente diminuição do conteúdo citoplasmático e preservação nuclear nas células tratadas com TFD, além da diminuição da quantidade de células por campo. A avaliação ultraestrutural por Microscopia de varredura mostra células com visível extração citoplasmática após a TFD, apontando uma lesão membranar. Novas avaliações precisam ser feitas como estabelecer um melhor protocolo para aumentar os efeitos da TFD. / Cancer is considered the second leading cause of death in Western countries. In the United States of America (USA) cancer deaths annually exceed the total of deaths in wars like Vietnam, Korea and the Great World Wars. Presenting as the most aggressive of the skin neoplasms, cutaneous melanoma is associated with circa 75% of the deaths from skin cancer. One of the therapies used in patients with melanoma and other pathologies is Photodynamic Therapy (PDT), which is based upon the use of dyes of low toxicity, which has selectivity for certain tissues or cells and low doses when activated by visible light induce cellular changes such as ROS production. The phenothiazic dyes are cationic molecules, absorption of light in the region between 620-660 nm, allowing greater spectrum tissue penetration, promoting higher activity of the compound in deeper tissues. The irradiation was performed with laser light with λ = 660 nm with 100 mW, energy density of 150 J/cm2 for 1 min. Quantification of cell viability was performed by the colorimetric method, and performed a reading in a microplate reader at 655nm. Determination of IC50 of Methylene Blue and Toluidine Blue O was 2.5 μM and 8.4 μM respectively. Using the protocol of PDT observed that there is one of the cytotoxic effects of phenothiazine compounds with statistical significance (p <0.05) in both MB and in TBO. Through optical microscopy by staining with fast Panotic was observed that there is an apparent decrease in the cytoplasm in cells treated with MB and TBO as well as reduced number of cells per field. The Scanning Electron Microscopy, shows cells with cytoplasm extraction, after PDT, indicated possibility, membrane damage. New assessments need to be made to establish a better protocol to potentiate the effects of PDT.

O objetivo deste estudo foi avaliar o efeito antibacteriano e a dissolução de biofilme promovido pela terapia fotodinâmica (PDT) associada com o hipoclorito de sódio (NaOCl) 2,5% e a clorexidina (CHX) sobre biofilmes mono-espécie e multi-espécies. No modelo de biofilme mono-espécie, quarenta e seis prémolares inferiores foram contaminados com cepas de Enterococcus faecalis (ATCCC 29212) por 21 dias. Os espécimes foram divididos em três grupos de acordo com a solução irrigadora utilizada: soro fisiológico, CHX 2% e NaOCl 2,5%. Após irrigação com 5 mL de cada irrigante, a PDT foi realizada. Amostras foram coletadas previamente aos protocolos de irrigação (S1), após irrigação (S2) e após PDT (S3). No modelo de biofilme multi-espécies, sessenta blocos de dentina bovina foram infectados intraoral e divididos em seis grupos: soro fisiológico, soro fisiológico/PDT, CHX, CHX/PDT, NaOCl e NaOCl/PDT. Microscopia confocal a laser foi usada para avaliar a porcentagem e o biovolume de células vivas e o volume total de biofilme. Todos os grupos reduziram as contagens de UFCs após os procedimentos de irrigação (S1-S2); porém a CHX e o NaOCl promoveram as menores contagens de UFCs (P < 0,05). A PDT diminuiu significativamente a contagem bacteriana no grupo do soro fisiológico (S2-S3; P < 0,05). No modelo de biofilme multi-espécies, a menor quantidade de células vivas foi observada nos grupos CHX, CHX/PDT, NaOCl e NaOCl/PDT, sem diferenças entre si (P > 0,05). A PDT não reduziu o volume total de biofilme (P > 0,05); porém parece diminuir o biovolume e a quantidade de células vivas após irrigação com CHX 2% e NaOCl 2,5%. A terapia fotodinâmica associada ao soro fisiológico reduziu a carga bacteriana em canais infectados com E. faecalis. A PDT parece reduzir a quantidade e o volume de células vivas, mas não o volume total de células em biofilme multiespécies induzido in situ. Finalmente, o tipo de irrigante foi decisivo para dissolver biofilme multi-espécies. / The aim of this study was to evaluate the antibacterial effect and the biofilm dissolution promoted by photodynamic therapy (PDT) associated with 2.5% NaOCl and 2% CHX over monospecies and multispecies biofilms. In monospecies biofilm model, forty-six mandibular premolars were contaminated with Enterococcus faecalis strains (ATCC 29212) broth culture for 21 days. Specimens were divided into three groups according to the irrigant used: saline, 2% of CHX and 2.5% of NaOCl. After irrigation with 5 mL of each irrigant, PDT was performed. Samples were collected at baseline (S1), after irrigation (S2) and after PDT (S3). In multispecies biofilm model, sixty bovine dentin blocs were infected intraorally, and divided into six groups: saline, saline/PDT, CHX, CHX/PDT, NaOCl and NaOCl/PDT. Confocal laser scanning microscopy was used to assess the percentage and the biovolume of live cells and the total biovolume. All groups reduced UFC’ counts after irrigation procedures (S1-S2); however CHX and NaOCl promoted the lowest UFCs counts (P < 0.05). PDT significantly reduced the bacterial counts in saline group (S2-S3; P < 0.05). In multispecies biofilm model, the lowest amount of live cells was observed in CHX, CHX/PDT, NaOCl and NaOCl/PDT groups, with no differences among them (P > 0.05). PDT did not reduce the total biovolume (P > 0.05); however it appears to decrease the biovolume and the amount of live cells after irrigation with 2% CHX and 2.5% NaOCl. PDT associated with saline reduced the bacterial load in canal infected with E. faecalis. PDT seems to reduce the amount and the biovolume of live cells, but did not reduce the total biovolume of cells in multispecies biofilm induced in situ. Finally, the irrigant was decisive to dissolve multispecies biofilm.

La thérapie photodynamique (PDT) est une technique thérapeutique qui permet un traitement localisé par irradiation lumineuse d’un photosensibilisateur (PS) grâce à la génération d’une espèce cytotoxique, généralement de l’oxygène singulet. Cependant, de nombreux PS sont également luminescents et les deux processus sont compétitifs. L’emploi de métaux de transition est connu pour améliorer le processus de PDT mais l’impact des ions lanthanides(III) en PDT est encore peu connu. Par ailleurs, l’utilisation de l’absorption biphotonique a de nombreux avantages parmi lesquels la possibilité d’exciter le PS dans la fenêtre de transparence biologique pour des applications en milieux biologiques.Les travaux de cette thèse visent à étudier quel est l’influence de la complexation d’un atome de lanthanide(III) à un PS sur la photophysique de désexcitation de ce dernier. Les complexes synthétisés et ceux étudiés ont montré que l’effet dépend du lanthanide(III). Il est ainsi possible, avec un choix judicieux du métal, de favoriser une voie de désexcitation par rapport à une autre. En particulier, l’ion Gd(III) se révèle avoir un effet bénéfique important pour la génération d’oxygène singulet et cet effet s’ajoute à celui que des atomes lourds comme le brome peuvent avoir. L’ion Yb(III) en revanche, favorise de manière générale le transfert d’énergie par effet d’antenne et la luminescence du lanthanide est alors le processus majoritaire. Enfin, l’emploi de Gd(III) complexé à un PS excitable à deux photons ouvre la voie à des agents théranostiques moléculaires combinant l’IRM en tant que fonction d’imagerie et la PDT pour la thérapie. / Photodynamic Therapy (PDT) is a therapeutic technique which consists in generating a highly reactive species, generally singlet oxygen, by shining light on a photosensitizer (PS). However, many PS are also luminescent and both processes are competitive. The use of transition metals is well known to enhance the PDT effect, but little is known about the effect of lanthanide(III) metals.On the other hand biphotonic absorption has numerous advantages, among them the possibility to excite the PS in the so-called biological transparency window for biological applications.The aim of this PhD is to get a better comprehension of the effect of complexation of a lanthanide(III) atom with a PS on the photophysics and deactivation pathways of the latter. The synthesis and conducted studies of lanthanide complexes showed that the effect is dependent on which lanthanide(III) metal is used. Thus by choosing carefully the lanthanide metal, one can favor one deactivation pathway over another. In particular, the Gd(III) ion turns out to be very efficient in promoting singlet oxygen generation and its effect is additive to the already known positive effect of heavy atoms such as bromine. On the opposite, the Yb(III) ion mainly favors the energy transfer through the antenna effect and the complex preferentially emits light.Finally, using Gd(III) linked to a two-photon excited PS opens the path to molecular theranostic probes combining MRI as a imagery technique and PDT as a therapeutic one.

Orientador: Prof. Dr. Maurício Domingues Coutinho Neto / Dissertação (mestrado) - Universidade Federal do ABC, Programa de Pós-Graduação em Ciência & Tecnologia - Química, 2015. / Derivados porfirínicos têm encontrado uso promissor como fotossensibilizadores na terapia fotodinâmica (TFD) por possuírem uma janela de absorção intensa dentro da região terapêutica desejada. Entretanto, processos de agregação em solução, comum a estes compostos, reduzem a eficiência da absorção de luz e da TFD como um todo. Esforços na direção de diminuir o grau de agregação destes compostos com a introdução de substituintes volumosos produziu resultados promissores. O presente trabalho estudou por meio de cálculos químico-quânticos os derivados porfirínico Clorina, Hematoporfirina e seu derivado 21,22 [N,N-dicarbonil-N-4(formilfenil)]-8,12-di[2-(metoxicarbonil)etil]-2,7,13,17-tetrametil-18 vinil2,21,22,23-tetrahidrobenzil[b] porfirina com o objetivo descrever a energética de agregação destes compostos em meio aquoso. Este último composto foi sintetizado recentemente e obteve sucesso em inibir processos de agregação em água. A Teoria do Funcional da Densidade aliada ao funcional M06-2X com função de base 6-311G(d,p) foi utilizada para o cálculo de perfis de interação na configuração H destes compostos em vácuo. A inclusão de efeitos do meio aquoso foi feita via o modelo de soltavação implícito IEF-PCM. Verificou-se também o impacto na energia de interação da introdução do Zinco(II) complexado ao anel porfirínico presente nos compostos. Os resultados obtidos concordaram com verificações experimentais de que a clorina é o composto com a maior tendência de agregação, e que o derivado substituído da Hematoporfirina possui a menor. Em todos os casos, o efeito do meio aquoso foi o de diminuir a energia de agregação quando comparado a resultados no vácuo. O efeito do meio aquoso é ainda mais pronunciado para os compostos substituídos com Zn(II). / Porphyrin derivatives have found promising use as photosensitizers in photodynamic therapy (PDT) for having an intense absorption window within the desired therapeutic area. Nevertheless, aggregation in solution processes, common to these compounds, reduces the efficiency of light absorption and TFD as a whole. Efforts in the direction of decreasing the degree of aggregation of these compounds through the introduction of bulky substituents yielded promising results. The present investigation used quantum-chemical calculation on the porphyrin derivatives Chlorine, Hematoporphyrin and a derivative thereof 21,22-[N, N-dicarbonyl-N-4- (formylphenyl)] - 8,12-Di [2- (methoxycarbonyl) ethyl ] -2,7,13,17-tetramethyl-18 vinil-2,21,22,23-tetrahidrobenzo[b] porphyrn in order to describe the energy aggregation of these compounds in an aqueous medium. This latter compound was synthesized recently and was successful in inhibiting aggregation processes in water. Density Functional Theory coupled to the M06-2X functional and 6-311G (d, p) basis function was used to produce interaction profiles in the H dimer configuration for these compounds vacuum. Solvent effects were included using the implicit solvent IEF-PCM method. The impact on the aggregation energetic due to the introduction of a Zn(II) to the porphyrinic ring was also investigated. Results agree with experimental observations that the chlorine compound has the greatest tendency to aggregate while the substituted hematoporphyrin derivative has the lowest. In all cases, the effect of the aqueous medium was to decrease the dimer interaction when compared to results in vacuum. Moreover, it was observed that effect of the aqueous medium is more pronounced for compounds substituted with Zn(II).