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High-energy light was generated from lower-energy photons through an upconversion process using a mixture of a photosensitizer and an emitter. Factors that influence efficiency of the process were studied. Several ruthenium(II) complexes coordinated with bi- and polypyridyl ligands were prepared and used as photosensitizers. Anthracene and its derivatives were used as emitters. In each experiment, the upconversion sample was irradiated with a laser and the emission was monitored. The emission spectra exhibited upconversion (415-513 nm), scattering laser light (514 or 632.8 nm), and phosphorescence (>550 nm). The laser beam was positioned close to the edge of the sample cuvette to avoid a reduction in the upconversion emission caused by self absorption. Increases in laser power, photosensitizer concentration, or emitter concentration increased the upconversion intensity (Iu). Dissolved oxygen caused a minor decrease in Iu. Different photosensitizer and emitter derivatives were tested. Homoleptic ruthenium complexes were more effective photosensitizers with DPA as emitter than their heteroleptic analogues. Upconversion was detected in the [Ru(deab)3](PF6)2 (deab = 4,4'-bis(N,N-diethylamino)-2,2'-bipyridine) and DPA system using helium-neon (632.8 nm) and argon ion (514 nm) lasers, indicating the same process can occur whenever the photosensitizer absorbs the incident radiation. A detailed mechanism is proposed in which an excitation photon is absorbed by a sensitizer to produce an excited triplet state. Energy is transferred from sensitizer to emitter by collision, generating triplet excited emitter. Two emitter triplets annihilate to produce one highly excited singlet. This singlet emits the upconversion photon. The steady-state approximation is used to explore the upconversion and phosphorescence (Ip) intensities. Ip has a first order dependence on laser power, while Iu varies between first and second order. The variable power dependence of Iu occurs because of the competition between triplet-triplet annihilation and other decay pathways. Finally, (Iu/Ip2) is proportional to the second order of DPA concentration. These results generate a better understanding of the upconversion process and they will help to direct the work of others to enhance the efficiency of photonic devices. Practical applications of upconversion, such as the development of better photovoltaic cells, will be aided by the work described herein.

A Terapia Fotodinâmica (TFP) é uma técnica para tratamento de câncer que usa um fotossensibilizador (FS) na presença de luz e oxigênio gerando espécies altamente reativas de oxigênio que levam as células tumorais à morte. <br />Neste trabalho foi realizado um estudo comparativo com três FSs: Photogem&reg; (PG), um derivado de hematoporfirina que está sendo usado em TFD no Brasil; Photodithazine&reg; (PZ), um derivado hidrossolúvel de mono-L-aspartil clorina, que está na fase clínica para aprovação e Hipericina (HY), um pigmento fotoativo encontrado na planta Hypericum perforatum e usado na medicina popular que está sendo considerado como um promissor agente fotodinâmico para o tratamento de tumores. Este estudo utilizou uma Hipericina sintetizada no Brasil e diversos parâmetros para comparar os três FSs: a concentração inibitória média (IC50) em linhagens celulares; a constante de velocidade de fotoxidação da albumina de soro bovino na presença dos FSs e luz determinada pelo decréscimo na fluorescência da BSA em 340 nm; a fotoxidação do ácido úrico acompanhada pelo decréscimo da banda característica do ácido úrico em 290 nm após irradiação na presença dos FSs como uma estimativa indireta do rendimento quântico de formação de oxigênio singlete (&Delta;&Phi;); o rendimento quântico de fluorescência utilizando rodamina B como padrão; a acumulação dos FSs em células em função do tempo de incubação e a estimativa da quantidade de radicais livres formados após irradiação através da técnica de captura de spins. Todos os resultados obtidos evidenciam uma maior eficiência fotodinâmica da HY seguida pelo PZ e depois por Photogem e, portanto sugerem a Hipericina como o FS de maior potencial para utilização em Terapia Fotodinâmica. / Photodynamic Therapy (PDT) is a technique for the cancer treatment that uses a photosensitizer (FS) in the presence of light and oxygen which combined are able to generate highly reactive oxygen species that lead to tumor cells death. <br />In this investigation, a comparative study with three FSs: Photogem &reg; (PG), a hematoporphyrin derivative being used in PDT in Brazil; Photodithazine &reg; (PZ), a soluble derivative of mono-L-aspartyl chlorin, which is in clinical phase for approval and Hypericin (HY), a photoactive pigment found in the plant Hypericum perforatum and used in popular medicine that is being considered as a promising agent for photodynamic treatment of tumors. The present study used a Hypericin synthesized in Brazil and several parameters to compare these three FSs: the mean inhibitory concentration (IC50) in cell lines; the rate constant for the photooxidation of bovine serum albumin in the presence of light and the FSs determined by the decrease in the fluorescence of BSA at 340 nm; the photooxidation of uric acid assessed by the decrease of the characteristic band of uric acid at 290 nm after irradiation in the presence of the FSs as an indirect estimate of the quantum yield of formation of singlet oxygen (&Delta;&Phi;); the quantum yield of fluorescence using rhodamine B as a standard; the accumulation of FSs in cells as a function of the incubation time, and the estimative of the produced free radicals after irradiation by the technique of spin trapping. All the results show a higher photodynamic efficiency of HY followed by PZ and then by Photogem suggesting Hypericin as the FS with the greatest potential for use in Photodynamic Therapy.

A hidrofobicidade e a estrutura planar do orbital &pi; estendido de fotossensibilizadores do tipo clorina e hipericina podem favorecer a agregação destes compostos em meio aquoso. Esta agregação pode reduzir a eficiência fotodinâmica e a aplicabilidade destes compostos em diagnósticos e na Terapia fotodinâmica. Uma estratégia para minimizar esta limitação é a modificação destas moléculas pela inserção de grupos hidrofílicos. Neste trabalho foram utilizadas técnicas espectroscópicas para caracterizar as propriedades físico-químicas e fotodinâmicas de derivados de clorina (CHL), e hipericina (HY) obtidos por meio de inserções dos grupos hidrofílicos trizma e glucamina, respectivamente: Clorina-Trizma (CHL-T) e Hipericina Glucamina (HY-G). Os resultados mostraram que estas modificações estruturais aumentaram em até 20% a solubilidade destes compostos em meio aquoso. No entanto, devido à solubilidade parcial dos fotossensibilizadores na ausência de cargas elétricas foram identificados agregados do tipo H em meio ácido, neutro e na presença de íons em solução aquosa. Tais agregados foram solubilizados em meio alcalino e por microambientes micelares dos surfactantes CTAB, SDS e Tween 20. Os agregados do tipo H acarretaram ainda na redução da constante de velocidade de fotobranqueamento e da formação de oxigênio singleto dos fotossensibilizadores em meio aquoso. Contudo, as clorinas foram cerca de 15 vezes mais eficientes do que a hipericinas na geração deste radical citotóxico. A análise sistemática do potencial fotodinâmico dos fotossensibilizadores em células VERO e HUVEC (não tumorais) e HEp-2 (tumoral) foi realizada por meio de um planejamento fatorial combinando-se a concentração, tempo de acumulação do fotossensibilizador no interior da célula e a dose de luz. Esta análise mostrou que o tempo de acumulação do fotossensibilizador é um parâmetro significante para se erradicar seletivamente as células cancerígenas. Ao contrário das células não tumorais, nas células HEp-2 a quantidade de fotossensibilizador acumulado foi proporcional à lipoficilidade dos fotossensibilizadores. A análise quimiométrica resultou ainda em um modelo matemático para a estimativa dos valores da concentração inibitória média que foi validada por meio de comparação estatística com os valores experimentais determinados para os fotossensibilizadores. As hipericinas foram mais fototóxicas para as células tumorais do que as clorinas. Nas células não tumorais os derivados foram menos citotóxicos, sugerindo o uso destes compostos para a inativação seletiva de células tumorais. Todas essas características permitem que os compostos sejam empregados como fotossensibilizadores em diagnósticos e tratamentos fotodinâmicos. / The hydrophobicity and planar structure of &pi; extended orbital of photosensitizers like chlorine and hypericin may favor the aggregation of these compounds in aqueous medium. This aggregation can reduce their photodynamic efficiency and applicability in Photodynamic Therapy and diagnosis. A strategy to minimize this limitation is the modification of these molecules by the inclusion of hydrophilic groups. In this study spectroscopic techniques were used to characterize the physical-chemistry and photodynamic properties of chlorin (CHL) and hypericin (HY) derivatives obtained by insertion of trizma glucamine and hydrophilic groups, respectively: Trizma-Chlorin (CHL-T) and glucamine Hypericin (HY-G). The results showed that these structural modifications increased by 20% the solubility of these compounds in an aqueous medium. However, due to partial solubility of the photosensitizers in electric charges absence, H-aggregates were found in acid, neutral and ions presence in aqueous solution. These aggregates were solubilized by alkaline medium and micelar microenvironments of CTAB, SDS and Tween 20. H-aggregates were also responsible for the minor photobleaching rate constant and singlet oxygen formation by photosensitizers in an aqueous medium. Although, chlorins were about 15 times more efficient than hypericins on the singlet oxygen generation. The systematic analysis of photosensitizers photodynamic potential in Vero and HUVEC (non-tumor cells) and HEp-2 (tumor cells) was done using a factorial design combining the concentration of the photosensitizer, accumulation time of it into the cell and light doses. This analysis showed that the photosensitizer accumulation time is a significant parameter to eradicate selectively tumor cells. In contrast to non-tumor cells, in HEp-2 cells the accumulation rate was proportional of the lipophylicity of photosensitizer. The chemometric analysis resulted also in a mathematical model to estimate the half inhibitory concentration values. It had been statistical validated by comparing the experimental values determined for the photosensitizers. The hypericins have been more phototoxic to tumor cells than chlorines. In non-tumor cells derivatives were more cytotoxic than original compounds suggesting the use of these compounds for the selective inactivation of tumor cells. All these characteristics allow the use of these compounds as photosensitizers in photodynamic diagnostics and treatments.

A hidrofobicidade e a estrutura planar do orbital &pi; estendido de fotossensibilizadores do tipo clorina e hipericina podem favorecer a agregação destes compostos em meio aquoso. Esta agregação pode reduzir a eficiência fotodinâmica e a aplicabilidade destes compostos em diagnósticos e na Terapia fotodinâmica. Uma estratégia para minimizar esta limitação é a modificação destas moléculas pela inserção de grupos hidrofílicos. Neste trabalho foram utilizadas técnicas espectroscópicas para caracterizar as propriedades físico-químicas e fotodinâmicas de derivados de clorina (CHL), e hipericina (HY) obtidos por meio de inserções dos grupos hidrofílicos trizma e glucamina, respectivamente: Clorina-Trizma (CHL-T) e Hipericina Glucamina (HY-G). Os resultados mostraram que estas modificações estruturais aumentaram em até 20% a solubilidade destes compostos em meio aquoso. No entanto, devido à solubilidade parcial dos fotossensibilizadores na ausência de cargas elétricas foram identificados agregados do tipo H em meio ácido, neutro e na presença de íons em solução aquosa. Tais agregados foram solubilizados em meio alcalino e por microambientes micelares dos surfactantes CTAB, SDS e Tween 20. Os agregados do tipo H acarretaram ainda na redução da constante de velocidade de fotobranqueamento e da formação de oxigênio singleto dos fotossensibilizadores em meio aquoso. Contudo, as clorinas foram cerca de 15 vezes mais eficientes do que a hipericinas na geração deste radical citotóxico. A análise sistemática do potencial fotodinâmico dos fotossensibilizadores em células VERO e HUVEC (não tumorais) e HEp-2 (tumoral) foi realizada por meio de um planejamento fatorial combinando-se a concentração, tempo de acumulação do fotossensibilizador no interior da célula e a dose de luz. Esta análise mostrou que o tempo de acumulação do fotossensibilizador é um parâmetro significante para se erradicar seletivamente as células cancerígenas. Ao contrário das células não tumorais, nas células HEp-2 a quantidade de fotossensibilizador acumulado foi proporcional à lipoficilidade dos fotossensibilizadores. A análise quimiométrica resultou ainda em um modelo matemático para a estimativa dos valores da concentração inibitória média que foi validada por meio de comparação estatística com os valores experimentais determinados para os fotossensibilizadores. As hipericinas foram mais fototóxicas para as células tumorais do que as clorinas. Nas células não tumorais os derivados foram menos citotóxicos, sugerindo o uso destes compostos para a inativação seletiva de células tumorais. Todas essas características permitem que os compostos sejam empregados como fotossensibilizadores em diagnósticos e tratamentos fotodinâmicos. / The hydrophobicity and planar structure of &pi; extended orbital of photosensitizers like chlorine and hypericin may favor the aggregation of these compounds in aqueous medium. This aggregation can reduce their photodynamic efficiency and applicability in Photodynamic Therapy and diagnosis. A strategy to minimize this limitation is the modification of these molecules by the inclusion of hydrophilic groups. In this study spectroscopic techniques were used to characterize the physical-chemistry and photodynamic properties of chlorin (CHL) and hypericin (HY) derivatives obtained by insertion of trizma glucamine and hydrophilic groups, respectively: Trizma-Chlorin (CHL-T) and glucamine Hypericin (HY-G). The results showed that these structural modifications increased by 20% the solubility of these compounds in an aqueous medium. However, due to partial solubility of the photosensitizers in electric charges absence, H-aggregates were found in acid, neutral and ions presence in aqueous solution. These aggregates were solubilized by alkaline medium and micelar microenvironments of CTAB, SDS and Tween 20. H-aggregates were also responsible for the minor photobleaching rate constant and singlet oxygen formation by photosensitizers in an aqueous medium. Although, chlorins were about 15 times more efficient than hypericins on the singlet oxygen generation. The systematic analysis of photosensitizers photodynamic potential in Vero and HUVEC (non-tumor cells) and HEp-2 (tumor cells) was done using a factorial design combining the concentration of the photosensitizer, accumulation time of it into the cell and light doses. This analysis showed that the photosensitizer accumulation time is a significant parameter to eradicate selectively tumor cells. In contrast to non-tumor cells, in HEp-2 cells the accumulation rate was proportional of the lipophylicity of photosensitizer. The chemometric analysis resulted also in a mathematical model to estimate the half inhibitory concentration values. It had been statistical validated by comparing the experimental values determined for the photosensitizers. The hypericins have been more phototoxic to tumor cells than chlorines. In non-tumor cells derivatives were more cytotoxic than original compounds suggesting the use of these compounds for the selective inactivation of tumor cells. All these characteristics allow the use of these compounds as photosensitizers in photodynamic diagnostics and treatments.

Antimicrobial peptides (AMPs) and photosensitizers (PS) have gained attention as potential alternatives to traditional antibiotics for the treatment of microbial infection due to the decreased likelihood for acquired resistance. However, many AMPs and PS suffer from insufficient activity, specificity, or a combination thereof. AMPs can require high concentrations for effective activity, leading to non-specific side effects and increased costs. PS, on the other hand, are quite active, but are typically hydrophobic and suffer from non-specific binding and damage to host tissues. To solve these problems, we report a novel PS-AMP construct of the soluble PS eosin Y conjugated to the selective AMP (KLAKLAK)_(2). Eosin Y has a high singlet oxygen quantum yield, which is suitable for photodynamic activity, although the solubility of eosin Y results in poor binding and activity toward membranes on its own. On the other hand, the specificity of (KLAKLAK)_(2) is high for an AMP, but could still benefit from enhanced activity at lower concentrations. The killing activity and binding specificity of eosin-(KLAKLAK)_(2) toward both bacteria and mammalian cells was assessed using microbiology, biochemistry, and fluorescence microscopy techniques. Additionally, the mechanism of eosin-(KLAKLAK)_(2) activity was investigated using liposome models to determine factors involved in binding and membrane disruption. Furthermore, novel applications of transmission electron microscopy (TEM) methods were employed to observe the photodynamic effects of eosin-(KLAKLAK)_(2) against bacteria. The PS-AMP conjugate eosin-(KLAKLAK)_(2) displays synergistic activity between PS and AMP in model liposome systems, and is capable of killing several clinically relevant bacteria, including the multi-drug resistant Acinetobacter baumannii AYE strain. Furthermore, bacterial killing is achieved in the presence of red blood cells (RBCs) and other mammalian cell lines without significant toxicity. Liposome models reveal that the lipid composition of bacteria is a potential factor responsible for the observed binding specificity and corresponding activity. Additionally, TEM methods show that eosin-(KLAKLAK)_(2) causes extensive membrane damage to both Gram positive Staph aureus and Gram negative Escherichia coli, indicating a primary cause of cell death. A model is proposed where the activities of the PS and AMP, respectively, facilitate the activity of one another, leading to enhanced membrane disruption, and effective antibacterial activity while maintaining cell selectivity.

Title: Spectroscopic Study of Singlet Oxygen in Cells and Model Systems Author: Marek Scholz Department: Department of Chemical Physics and Optics Supervisor: doc. RNDr. Roman Dědic, Ph.D., KChFO Abstract: Singlet oxygen (1O2), the first excited state of molecular oxygen, plays many important roles in nature and technology. The work is aimed at development of novel methods for monitoring of 1O2 in cells and other biological samples. Two main ap- proaches were employed: direct detection of the very weak near-infrared phospho- rescence of 1O2, and detection of Singlet Oxygen-Feedback Delayed Fluorescence (SOFDF), which is the emission from the photosensitizer induced by energy transfer from 1O2. The first part of the thesis introduces the basic concepts of photophysics and photochemistry of 1O2: its generation, deactivation, applications, and overview of detection methods. The second part presents the experimental results. Wide-field mi- crospectroscopic detection of 1O2 phosphorescence enabled us to acquire 1O2-based images and near-infrared spectra from single cells incubated with photosensitizers. However, the direct detection suffers from the inherently very low phosphorescence quantum yield. It is shown that SOFDF may overcome this problem and become a promising alternative tool for studies of 1O2 and...

A Terapia Fotodinâmica (TFP) é uma técnica para tratamento de câncer que usa um fotossensibilizador (FS) na presença de luz e oxigênio gerando espécies altamente reativas de oxigênio que levam as células tumorais à morte. <br />Neste trabalho foi realizado um estudo comparativo com três FSs: Photogem&reg; (PG), um derivado de hematoporfirina que está sendo usado em TFD no Brasil; Photodithazine&reg; (PZ), um derivado hidrossolúvel de mono-L-aspartil clorina, que está na fase clínica para aprovação e Hipericina (HY), um pigmento fotoativo encontrado na planta Hypericum perforatum e usado na medicina popular que está sendo considerado como um promissor agente fotodinâmico para o tratamento de tumores. Este estudo utilizou uma Hipericina sintetizada no Brasil e diversos parâmetros para comparar os três FSs: a concentração inibitória média (IC50) em linhagens celulares; a constante de velocidade de fotoxidação da albumina de soro bovino na presença dos FSs e luz determinada pelo decréscimo na fluorescência da BSA em 340 nm; a fotoxidação do ácido úrico acompanhada pelo decréscimo da banda característica do ácido úrico em 290 nm após irradiação na presença dos FSs como uma estimativa indireta do rendimento quântico de formação de oxigênio singlete (&Delta;&Phi;); o rendimento quântico de fluorescência utilizando rodamina B como padrão; a acumulação dos FSs em células em função do tempo de incubação e a estimativa da quantidade de radicais livres formados após irradiação através da técnica de captura de spins. Todos os resultados obtidos evidenciam uma maior eficiência fotodinâmica da HY seguida pelo PZ e depois por Photogem e, portanto sugerem a Hipericina como o FS de maior potencial para utilização em Terapia Fotodinâmica. / Photodynamic Therapy (PDT) is a technique for the cancer treatment that uses a photosensitizer (FS) in the presence of light and oxygen which combined are able to generate highly reactive oxygen species that lead to tumor cells death. <br />In this investigation, a comparative study with three FSs: Photogem &reg; (PG), a hematoporphyrin derivative being used in PDT in Brazil; Photodithazine &reg; (PZ), a soluble derivative of mono-L-aspartyl chlorin, which is in clinical phase for approval and Hypericin (HY), a photoactive pigment found in the plant Hypericum perforatum and used in popular medicine that is being considered as a promising agent for photodynamic treatment of tumors. The present study used a Hypericin synthesized in Brazil and several parameters to compare these three FSs: the mean inhibitory concentration (IC50) in cell lines; the rate constant for the photooxidation of bovine serum albumin in the presence of light and the FSs determined by the decrease in the fluorescence of BSA at 340 nm; the photooxidation of uric acid assessed by the decrease of the characteristic band of uric acid at 290 nm after irradiation in the presence of the FSs as an indirect estimate of the quantum yield of formation of singlet oxygen (&Delta;&Phi;); the quantum yield of fluorescence using rhodamine B as a standard; the accumulation of FSs in cells as a function of the incubation time, and the estimative of the produced free radicals after irradiation by the technique of spin trapping. All the results show a higher photodynamic efficiency of HY followed by PZ and then by Photogem suggesting Hypericin as the FS with the greatest potential for use in Photodynamic Therapy.

L'augmentation du nombre de cancers de faible taille dans le monde a incité le développement de nouveaux nanomatériaux multifonctionnels appliqués à de nouvelles thérapies non invasives. Ces nouvelles thérapies peuvent éliminer sélectivement la tumeur en réduisant ou en supprimant les effets secondaires induits dans les tissus sains par les traitements actuels, tels que la chimiothérapie ou la radiothérapie, qui présentent une efficacité élevée mais une faible sélectivité. Ce travail décrit l'élaboration de nanomatériaux pour le diagnostic et le traitement des cancers de faible taille grâce à une nouvelle thérapie: la thérapie photodynamique (PDT). Cette nouvelle technique, implique l'activation d'une molécule photosensibilisatrice (PS) grâce à des longueurs d'onde spécifiques. Cette activation conduit à des cascades de transfert d'énergie qui produisent des espèces oxygénées réactives cytotoxiques provoquant la mort cellulaire.Dans un premier temps, l'élaboration de nanoparticules de silice mésoporeuses (MSN) contenant un agent photosensibilisant de type porphyrine est présentée pour le traitement in vitro du cancer de la prostate et du rétinoblastome grâce à la thérapie photodynamique à un photon. Des nanoparticules fonctionnalisées avec de nouveaux ligands ont été essayées pour cibler les nanoparticules vers les cellules cancéreuses de la prostate. La diminution de la taille des nanoparticules à 20 nm a été élaborée pour traverser la barrière hémato-rétinienne et traiter les rétinoblastomes.D'autre part, deux nouveaux types de nanomatériaux ont été conçus pour le traitement à deux photons qui conduit à une pénétration plus profonde dans les tissus. Des nanoparticules polysilsesquioxane pontés (BS) et des nanoparticules d’organosilice mésoporeuses (PMO) ont été conçues à partir de différents types de molécules photosensibilisatrices tétra-silylées ou octa-silylées et de bis-organo-alcoxysilanes comme l'éthane, l'éthylène ou le disulfide. L’efficacité des BS en imagerie à deux photons en thérapie photodynamique a été démontrée in vitro. Des nanoparticules de BS à base de disulfides ont été conçues comme nouveaux nanomatériaux biodégradables.Enfin, en plus de l'imagerie et la thérapie, les PMO ont été testés in vitro pour la délivrance de médicaments en raison de leur mésoporosité. La gemcitabine et doxorubicine ont été encapsulées dans les pores obtenant des charges élevées en médicaments. Outre les photosensibilisateurs classiques, des PMO cœur-coquille contenant des nanodiamants ont été testés en tant que PS. Pour finir, des PMO à base de porphyrines sont présentés pour la délivrance de gènes in vitro et in vivo utilisant le poisson-zèbre comme modèle. / Nowadays, the increase of the number of low-size cancers in the world has prompted the development of novel multifunctional nanomaterials applied to new non-invasive therapies. These new therapies are expected to selectively eradicate the tumor, decreasing or suppressing the side effects induced in healthy tissues by current treatments. This study describes the elaboration of nanomaterials for the diagnostic and the therapy of low size cancers through a novel therapy: photodynamic therapy (PDT). This new technique involves the activation of a photosensitizer molecule (PS) with specific wavelengths of light giving rise to energy transfer cascades that yield cytotoxic reactive oxygen species leading to apoptotic and necrotic cell death.First, the elaboration of mesoporous silica nanoparticles (MSN) containing a porphyrin photosensitizer are presented for the treatment in vitro of prostate cancer and retinoblastoma through one-photon therapy. Functionalized nanoparticles with new ligands were synthesized to target the nanoparticles to prostate cancer cells. The decrease of the nanoparticle size to 20 nm was elaborated to cross the blood-retinal barrier and treat retinoblastomas.On the other hand, two new types of nanomaterials were designed for two-photon nanomedicine which leads to a deeper penetration in tissues. Bridged silsesquioxane (BS) and periodic mesoporous organosilica (PMOs) nanoparticles were designed from different types of tetra or octasilylated-photosensitizers and bis-organoalkoxysilanes such as ethane, ethylene or disulphide. Pure PS bridged silsesquioxane nanoparticles lead to efficient two-photon imaging and photodynamic therapy which were demonstrated in vitro. Disulfide-based BS nanoparticles were designed as biodegradable nanomaterials.Finally, in addition to the imaging and therapy, PMOs nanoparticles were tested in vitro as nanocarriers for drug delivery due to their mesoporosity. Gemcitabine or doxorubicin were encapsulated into the pores leading to high drug loadings. Beside the classical photosensitizers, nanodiamonds core-shells PMOs were tested as PDT agent. In addition, pure porphyrin nanoPMOs are presented for gene delivery in vitro and in vivo in a zebrafish model.

Much of the energy used in the United States and around the globe is obtained from petroleum, natural gas, and coal. Photocatalytic CO2 reduction can be used to transform CO2 to useful fuels and making fossil fuels more renewable. Input of energy is required, and the sun can provide the required energy for this transformation. Photosensitizer, catalyst, and electron donor are required for photocatalytic CO2 reduction. Due to lack of earth-abundant sensitizers, zinc dipyrrin complexes were synthesized by previous group members and have been used as photosensitizers in this research. The ground and excited state electrochemical properties of two zinc dipyrrin complexes were determined in polar and nonpolar solvents and the measured potentials were used to match the zinc sensitizers with an energetically appropriate iron porphyrin catalyst and a benzylthiol sacrificial electron donor. Lastly, pure CO2 gas was used as the source of carbon for the reduction of CO2 by photocatalysis with the zinc photosensitizers, iron catalyst and sacrificial electron donor. The products formed in headspace were analyzed by GC