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1
Fisher, Daniel C. "PREPARATION AND APPLICATION OF CATALYSTS FOR THE STEREOSPECIFIC REDUCTION AND PHOTOOXYGENATION OF OLEFINS IN CONTINUOUS OPERATIONS: A NOVEL METHOD FOR THE PRODUCTION OF ARTEMISININ." VCU Scholars Compass, 2017. https://scholarscompass.vcu.edu/etd/5159.
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Over the last two centuries, the discovery and application of catalysts has had a substantial impact on how and what chemicals are produced.Given their broad significance, our group has focused on developing new catalyst systems that are recoverable and reusable, in an attempt to reduce concomitant costs.
Our efforts have centered on constructing a recyclable chiral heterogeneous catalyst capable of effecting asymmetric hydrogenations of olefins with high stereoselectivity. A class of phosphinoimidazoline ligands, developed by researchers at Boehringer-Ingelheim, known as BIPI ligands, have proven efficacious in the asymmetric reduction of alkenes. However, these chiral ligands are homogeneous and coordinated to precious metals, rendering them irrecoverable and expensive. To address these issues, our group has derivatized the BIPI ligand-metal complex and immobilized it to the surface of graphene oxide as well as polystyrene. Their efficacy and recyclability toward the asymmetric hydrogenation of a functionalized olefin have been evaluated.
Another facet of our work has included developing a cost effective synthetic process to artemisinin, the gold standard drug in the treatment of malaria.As a natural product, artemisinin’s worldwide supply remains highly unpredictable, contributing to great price volatility.Combining the benefits of catalysis and the advantages of continuous flow chemistry, our research has sought to develop an economical approach to convert a biosynthetic precursor, artemisinic acid, to artemisinin in three chemical transformations.
High-throughput experimentation allowed us to screen a prodigious number of catalysts and identify those effective in the asymmetric hydrogenation artemisinic acid to dihydroartemisinic acid, the first step in the transformation. This screening directed us to an inexpensive, heterogeneous ruthenium catalyst. The second step of the process includes the photooxygenation of dihydroartemisinic acid, which involves photochemically generated singlet oxygen. We have evaluated a commercially available heterogeneous photocatalyst packed in a transparent bed, surrounded by light emitting diodes in the continuous photooxygenation of dihydroartemisinic acid to dihydroartemisinic acid hydroperoxide. The third and final step, an acid induced hock cleavage, initiates an intricate cascading reaction that installs an endoperoxide bridge to deliver artemisinin. Our process afforded a 57% yield from dihydroartemisinic acid to artemisinin.
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Ullah, Aman. "Epidemiology of bovine brucellosis in Sindh, Pakistan." Thesis, University of Edinburgh, 2013. http://hdl.handle.net/1842/17983.
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Brucellosis is endemic in many livestock worldwide especially developing countries. The aims of this study were to estimate the seroprevalence of bovine brucellosis and risk factors associated with the seropositivity in rural and peri-urban buffaloes and cattle populations of Sindh. Firstly, a cross sectional study was conducted to estimate the seroprevalence of bovine brucellosis in cattle and buffaloes of Sindh province, Pakistan. Serum samples (2600) were tested using Rose Bengal Plate Test. The overall seroprevalence of brucellosis in Sindh province was 13.96% (95% C.I.; 11.55 - 16.37). Of the 917 herds tested, 232 or 25.30% herds (95%C.I.; 22.51-28.24) were positive for brucellosis. The adult animals were 2.05 (95% C.I.; 1.14-3.68, P= 0.02) times more likely to test positive for brucellosis. The animals in a peri-urban dairy production system were 2.07 times (95%C.I.; 1.09-3.90, P = 0.03) times more likely have brucellosis. The species or sex of animal did not appear to affect the risk of seropositivity in cattle or buffalo in this population. Secondly, a cross sectional survey was conducted to understand the structure and composition of farms, animal husbandry and management practices in peri-urban dairy colonies in Karachi and farmers’ awareness of zoonoses. The mean herd size was 93.58 animals and 88.01% of these animals were female buffaloes. Of 326 farms surveyed, only 37.42% were able to associate animals with transmission of diseases in human. The characteristics of peri-urban dairy farms in Karachi are discussed. Thirdly, the value of FTA® cards in detecting the Brucella DNA in milk samples was estimated by determining the detection limits of genus specific ERI PCR assay for FTA® cards and comparing the PCR results from whole sediments taken from culturing pooled milk samples with taking sediment on FTA® cards. The detection limits of this method ranged from 6.6 x 103 cfu/ml for B. abortus to 7.17 x 106 cfu/ml for B. suis. Assuming the results of ERI PCR for the whole sediment as gold standard (method 1), the method using sediment on FTA® cards as test samples (method 2) showed a diagnostic sensitivity of 81.44% (95% C.I.; 75.54-87.33) but a poor diagnostic specificity of 42.86% (95%C.I.; 16.95-68.78). The kappa value, κ, was 0.14 (p = 0.02) demonstrating a poor agreement between the two methods. Lastly, 181 bulk milk samples were used to estimate the herd level prevalence of bovine brucellosis in Landhi dairy colony, Karachi. The ERI PCR was used to test these samples. The herd prevalence was estimated as 92.26% (95% C.I.; 88.34-96.19). For each level (50 animals) increase in herd size, the risk of herd being brucellosis positive increases by 2.38 times. The herds that have a male animal for breeding are 0.09 times less likely to have brucellosis. The history of abortion, presence of small ruminants or the regions of animal purchase don’t appear to have any association with the risk of brucellosis at a herd level in this population at LDC, Karachi. A high seroprevalence of bovine brucellosis in livestock population in Sindh and a very high herd level prevalence in peri-urban dairy farms in particular poses a serious threat to the public health and livestock production in Sindh, Pakistan.
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Pessoni, Laurence. "Synthèse de polystyrène greffé rose Bengale pour l’élaboration de films poreux photo-actifs structurés en nid d’abeille." Thesis, Pau, 2013. http://www.theses.fr/2013PAUU3028/document.
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Nous évaluons des films polymères poreux structurés en tant que nouveaux supports pour des photosensibilisateurs de l’oxygène singulet. L’objectif de cette association est l’obtention de matériaux photo-actifs à grande surface d’échange. Ces surfaces polymères, structurées ici en nid d’abeille, sont obtenues par la technique « breath figure » (trad. figure de souffle), à partir de polymères bien définis synthétisés par polymérisation radicalaire contrôlée par des nitroxydes (NMP), par transfert d’atome (ATRP) et par transfert réversible par addition/fragmentation (RAFT). Le photosensibilisateur rose Bengale a été greffé de manière covalente au polymère, soit par post-greffage sur un polymère précurseur, soit par modification d’un monomère fonctionnel puis copolymérisation de ce dernier avec du styrène. Ces différentes synthèses conduisent à des films contenant différents taux de rose Bengale. Les films ont été examinés en microscopie (fluorescence, confocale et champ large, électronique à balayage) afin d’établir la structuration des films et la localisation des espèces fluorescentes. L’efficacité des films polymères pour la photo-oxydation a été testée à l’interface liquide/solide en suivant par spectroscopie UV-visible la dégradation du dihydroxynaphtalène (DHN) ou de l’α-terpinène par l’oxygène singulet produit sous irradiation visible. Les films structurés sont environ cinq fois plus efficaces que les films non-poreux de même composition utilisés dans les mêmes conditions, ce qui s’explique par leur surface spécifique et par la localisation préférentielle du rose Bengale à la surface du matériau<br>We evaluate structured porous polymer films as new substrates for photosensitizers of singlet oxygen, with a view to obtaining photo-active materials with high specific exchange areas. Here, honeycomb polymer films are obtained by the breath figure process, using well defined polymers synthesized by nitroxide-controlled radical polymerization (NMP), atom transfer polymerization (ATRP) and reversible addition/fragmentation transfer (RAFT). The photosensitizer, rose Bengal, is either post-grafted covalently to the polymer precursor, or pre-grafted to a monomer functional unit which is copolymerized with polystyrene. These syntheses lead to films with different rose Bengal concentrations. We determine the structure of the films and the location of the fluorescent dye by scanning electron microscopy and widefield and confocal microscopy. Efficiency of production of singlet oxygen was tested at a solid/liquid interface by monitoring the oxidation of dihydroxynaphthalene and α-terpinene, using UV-visible absorption spectroscopy. Honeycomb films are about five times more efficient than non-porous films of the same composition used in the same, as may be explained by their higher specific surface area and the preferential location of the photosensitizer at the film surface
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Andrieux, Fabrice Pierre Louis. "The micro-optical ring electrode : development of a novel thin ring based device for spectrophotoelectrochemistry and its application to the study of rose bengal." Thesis, University of Central Lancashire, 2004. http://clok.uclan.ac.uk/20044/.
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Electrochemists have at their disposal, for the study of photo- electrochemical systems, a range of sensors and devices such as rotating optical disc ring electrodes, optically transparent electrodes and optically transparent thin layer electrodes. A microelectrode is an electrode with at least one of its characteristic dimensions of less than 50 pm. This provides a number of advantages to such devices used in analytical techniques: it allows access to hitherto inaccessible media, the low current associated allows for a low analyte consumption and ohmic polarisation, it also renders possible the detection of short-lived species. Based on a thin ring microelectrode design and using the electrode shank as a light guide, the Micro- Optical Ring Electrode (MORE) is a novel device that has been designed and constructed to permit electrochemical investigation of photochemically generated solution species. Thin rings exhibit high rates of material flux to the electrode surface, facilitating the detection of short lived- photo-generated solution intermediates. To exploit this advantage, we have prepared MOREs with ring inner radius to ring outer radius ratios in excess of 0.999. Electrode behaviour in the dark has been characterised by the use of ferricyanide in conjunction with predictive mathematical models of the time dependence of the current at micro ring electrodes in the dark. Further device improvement has involved the design and construction of a more robust light guide-to-electrode coupling. The resultant increase in the transmitted light intensity and its reproducibility have facilitated the study of the spectral dependence of the photocurrents observed from photo- electro- active systems as well as their correlations to the concentrations of both the photo- active species and the quencher. By exploiting the properties of discontinuous integrals of Bessel Functions, a mathematical model of the behaviour Of the device has been developed allowing for the generation of asymptotic analytical expressions describing: (I) The distribution of the photoexcited analyte over the electrode surface; (ii) The tong illumination time (steady state) photocurrent as a function of electrode dimensions, light intensity and lifetime of the photogenerated species; and (iii) The time dependence of the tight-on photocurrent transient as a function of species lifetime. These expressions can be used to describe and explain the form of the Ru(II)/Fe(III) data described above and, coupled to the analyte-specific use afforded by the light selectivity of the device, make the MORE a powerful analytical tool capable of potentially calibrationless use. The spectral dependence of the photocurrent at the MORE has been investigated and found to correspond to the singlet-to-singlet, metal-to-ligand charge transfer band of the UV-Visible spectrum of ruthenium(II) 2,2'-trisbipyridine complex. The value of the Stern-Volmer constant for the quenching of photoexcited Ru(bipy)3 2 by Fe3 obtained at the MORE (0.358m 3 mor1) compares favourably with the value obtained from fluorescence measurements (0.9 m 3 mol' [Un, 1976]). The photochemistry of organic dyes is a very important field especially in the understanding of the mechanisms involved in the production of singlet oxygen, with application ranging from pollution remediation processes to photodynamic therapy (PDT), an advanced cancer treatment. Singlet oxygen can be produced by photoexcitation of an organic molecule whose excess energy may then be passed on to a neighbouring oxygen molecule that is forced into its highly reactive singlet state. Effectiveness of singlet oxygen production is usually measured either by the phosphorescence of singlet oxygen at 1270nm or by use of singlet oxygen traps. Both these methods have limitations, especially in vivcr therefore we wish to extend the applications of the MORE to direct electrochemical singlet oxygen detection. To this end, we have investigated the photo-electrochemical properties of a singlet oxygen precursor: rose bengal (RB). The dark electrochemistry of RB was investigated using the Electrochemical Quartz Crystal Microbalance and the Rotating Ring Disc Electrode. We have identified all electrochemical processes associated with rose bengal, and attempted the detection of photoexcited rose bengal in both anaerobic conditions, as well as direct detection of singlet oxygen.
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Favre-Besse, Franck-Cyril. "Modulateurs du transport vésiculaire du glutamate : développement d’outils pharmacologiques et de diagnostic pour la maladie d’Alzheimer." Thesis, Paris 5, 2012. http://www.theses.fr/2012PA05P639/document.
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Les transporteurs vésiculaires du glutamate (VGLUTs) sont impliqués dans la recapture du glutamate du cytosol vers les vésicules présynaptiques. Depuis leurs caractérisations récentes en 2000, leurs implications dans plusieurs maladies neurodégénératives ont été démontrées. Ils jouent ainsi un rôle primordial dans la transmission nerveuse glutamatergique. Deux colorants naturels, le Rose Bengale et le Bleu Trypan, restent les meilleurs inhibiteurs connus à ce jour, avec respectivement des CI50 de 25 et 50 nM. Dans un premier temps, nous avons conçu et optimisé une série d’analogues basée sur le synthon Rose Bengale (inhibiteur non-compétitif). Ce travail a notamment permis de mettre en évidence l’effet des formes tautomères (quinone et lactone) sur l’inhibition des VGLUTs. Ainsi la forme quinonique, présente à pH physiologique, a été confirmée comme étant la seule capable de bloquer la recapture du glutamate. Dans un second temps, nous nous sommes intéressés à la famille du Bleu Trypan (inhibiteur compétitif) et nous avons déterminé la structure minimale active avec l’objectif de rendre ces molécules plus « drug-like ». En effet, l’intérêt de ce projet est de développer de petites structures aisément radiomarquables pour une utilisation dans un contexte physio-pathologique<br>Vesicular glutamate transporters (VGLUTs) are involved in the recapture and storage of glutamate from cytol to secretory synaptic vesicules. Since their recent characterization in 2000, their implication in several neurodegenerative disorders have been demonstrated. They play a crucial role in glutamatergic neurotransmission. Natural dyes, such as Rose Bengal and Tryptan Blue are the best known inhibitors with IC50 values of 25 and 50 nM, respectively. Firstly, we designed and optimized a series of analogues based on the synthon Rose Bengal (non-competitive inhibitor). This work has especially enabled to highlight the effect of tautomeric forms (quinone and lactone) on the inhibition of VGLUTs. Thus, the quinone form, present at physiological pH, was confirmed as the only able to block the reuptake of glutamate. Secondly, we have been interested in the family of Trypan Blue (competitive inhibitor) and we determined the minimal active structure in order to render these molecules more "drug-like". Indeed, the interest of this project is to develop small structures easily radiomarquable to use in a physiopathological context
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Nouioua, Fares. "La désinfection en endodontie." Thesis, Montpellier, 2019. http://www.theses.fr/2019MONTT079.
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Les bactéries ont été désignées comme le facteur étiologique principal des échecs du traitement endodontique. Le principal défi des techniques actuelles de débridement est d’assurer l’élimination de ces bactéries dans la zone apicale et ses ramifications canalaires. A ce niveau, le praticien est souvent confronté à la gestion d’un équilibre délicat, entre une désinfection efficace et la sécurité du patient. Les objectifs de ce mémoire sont doubles :1) Développer de nouvelles méthodes de débridement et de désinfection des parties apicales de l’espace canalaire.2) Évaluer l’innocuité de ces techniques vis-à-vis des tissus parodontaux, en cas d’extrusion des produits désinfectants à travers le foramen apical.Pour atteindre les objectifs de l’étude dans un premier temps, l’optimisation de l’action physique de l’irrigation a été mise en avant, par l’évaluation d’un dispositif à pression positive élevée, équipé d’une canule flexible, et comportant à son extrémité trois évents latéraux.L’association de ces deux éléments devrait combiner les avantages d’un débit d’irrigation élevé avec ceux de cette canule spéciale. L’analyse de la capacité de pénétration de l’irrigant et d’élimination des débris, dans la zone apicale, ont montré que ce nouveau dispositif à pression élevée a été significativement plus efficace que l’irrigation par seringue conventionnelle, ou par seringue associée à l’activation sonique.Sachant que la tendance actuelle est en faveur des dispositifs à pression négative, le dispositif testé dans notre étude a montré néanmoins des résultats de débridement prometteurs, grâce à sa pression positive. Cependant, la probabilité de provoquer l’extrusion de l’irrigant vers le péri-apex est importante. Pour évaluer l’extrusion de la solution d’irrigation, notre recherche bibliographique a mis en évidence le manque de pertinence des modèles expérimentaux les plus utilisés par les études de la discipline. Nous avons donc mis au point une nouvelle méthode expérimentale pour une évaluation dynamique du volume d’irrigant extrudé (évaluation en temps réel). Ce modèle a permis de comparer la nouvelle canule à trois évents avec des aiguilles d’irrigation de calibres et de formes variés.Dans un deuxième temps, la capacité de désinfection photo-dynamique d’une diode laser bleue a été évaluée sur des cultures d’Enterococcus faecalis, à l’aide de plusieurs photo-sensibilisants. Cette bactérie résistante, à de nombreux antimicrobiens, a été fréquemment isolée dans les lésions endodontiques secondaires. La combinaison de la PDT antimicrobienne au débridement conventionnel devrait permettre à leurs principes actifs (l’oxygène singulet et les agents chlorés) de supprimer complètement les micro-organismes résistants dans la zone apicale et ses ramifications. L’exposition de 10s seulement du Rose Bengale à la diode laser bleue a été suffisante pour réduire significativement la viabilité d’E.faecalis en suspension ou en biofilm mono-espèce.Enfin, la recherche de la cytotoxicité de ce protocole antimicrobien PDT sur des cellules pulpaires a mis en évidence une toxicité liée surtout à la concentration élevée des photosensibilisants utilisés<br>Bacteria have been confirmed as the main etiological factor for root canal infection as well as for root canal treatment failure. The main challenge of conventional debridement techniques is to ensure the removal of these bacteria in the apical zone and its ramifications. At this area, the practitioner is often faced with managing a delicate balance between effective disinfection and patient safety. The objectives of this thesis are twofold:1) Develop new methods of debridement and disinfection of the apical root canal space.2) Evaluate the safety of these techniques with respect to parodontal tissues, in case of extrusion of the antimicrobial agent through the apical foramen.To achieve both the objectives, the optimization of the physical effect of irrigation was put forward at the first. A high positive pressure device equipped with a speciale cannula, was evaluated in term of apical penetration ability and apical debris removal, compared to conventional syringe irrigation and syringe irrigation associated to sonic activation.Despite the current trend in favor of negative pressure irrigation méthod, the device tested in our study nevertheless showed promising results in root canal debridement, thanks to its positive pressure. However, there is a high probability of periapical extrusion of irrigant. Our search highlighted the lack of relevance of the experimental models most used in the endodontic literature. We have therefore started to develop a new experimental method for dynamic evaluation of extruded volume of irrigant (real-time evaluation). This model has made it possible to compare this new specific cannula with needles of varying sizes and designs.In a second step, the antimicrobial PDT capacity of a blue laser diode, using several photosensitizers, was evaluated on Enterococcus faecalis cultures. The combination of antimicrobial PDT and conventional debridement should allow the active agents (singlet oxygen and chlorinated agents) to completely suppress resistant microorganisms in the apical area. Only 10s of blue light exposuse of Rose bengal was sufficient to significantly reduce the viability of E. faecalis in planctonik form or in mono-specie biofilm.Finally, the investigation of the cytotoxicity of this antimicrobial PDT protocol on pulp cells has demonstrated a toxicity related mainly to the high concentration of photosensitizers used
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Planas, Marquès Oriol. "Novel approaches to singlet oxygen photosensitization in the nano- and bio-era." Doctoral thesis, Universitat Ramon Llull, 2017. http://hdl.handle.net/10803/404841.
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En aquesta tesis es detallen noves aproximacions nano- i biomoleculars amb l’objectiu de millorar la fotosensibilització i detecció d’oxigen singlet en medi biològic.
En primer lloc es presenta una nova reacció fluoro- i cromogènica pel marcatge de proteïnes i nanopartícules amb derivats de porficè. Concretament, la reacció de porficens isotiocianat amb amines primàries i secundaries generen 2-aminotiazolo[4,5-c]poricè derivats amb un desplaçament concomitant en els seus espectres d’absorció i emissió per més de 70 nm cap al vermell. Aquesta reacció inesperada ha estat racionalitzada en base a la ciclació espontània del derivat 9-tiourea porficè generat en la reacció per donar lloc a un tiazoloporficè fusionat. L’abast de tal reacció s’ha expandit a altres derivats de porficè com els 9-amidoporficens. Finalment, s’ha utilitzat porficens isotiocianat pel marcatge de biomolècules i nanopartícules, lliurant conjugats teranòstics al infraroig proper.
En segon lloc s’ha estudiat l’efecte de la morfologia de les nanopartícules se sílice sobre la capacitat de producció i desactivació d’oxigen singlet per part de la protoporfirina IX. L’agregació del fotosensibilitzador en la superfície de la nanopartícula limita la producció d’oxigen singlet. Per altra banda, a mesura que augmenta la porositat del nanomaterial es possible detectar diferents poblacions d’oxigen singlet; una d’elles és capaç d’escapar de la superfície de les nanopartícules i de decaure en el dissolvent mentre que l’altra es manté atrapada dins dels porus de sílice. Els resultats revelen que controlar el grau d’agregació del fotosensibilitzador i la seva localització en la matriu de sílice són factors crítics a tenir en compte en la preparació de materials nanoporosos per a l’alliberació d’oxigen singlet.
Finalment s’han dissenyat i estudiat fotosensibilizadors plasmònics capaços d’augmentar la producció i el decaïment radiant del oxigen singlet. Mitjançant tècniques de espectroscòpia estacionària i resoltes en el temps es demostra que el nucli de plata exerceix un efecte dual a través d’una absorció incrementada de llum i un augment en el decaïment radiant d’oxigen singlet, fet que es tradueix en un augment de la seva fosforescència. A més a més es demostra que l’augment en la producció i en el decaïment radiant d’oxigen singlet depèn enormement de la proximitat entre fotosensibilitzador i nanopartícula plasmònica. D’aquesta manera s’han identificat 3 règims diferents a mesura que el fotosensibilitzador s’allunya de la nanoestructura plasmónica, essent la zona de major augment aquella compresa en distancies entre 10 i 20 nm del nucli metàl·lic. Addicionalment s’han utilitzat les nanopartícules per el tractament fotodinàmic de bactèries Gram-positives i Gram-negatives, observant un augment tant de la seva activitat antimicrobiana com en el límit de detecció d’oxigen singlet.<br>En esta tesis se detallan nuevas aproximaciones nano- y biomoleculares para mejorar la fotosensibilización y detección del oxígeno singlete en medio biológico.
En primer lugar se presenta una nueva reacción fluoro- y cromogénica para el etiquetado de proteínas y nanopartículas con derivados de porficeno. Concretamente, la reacción de porficenos isotiocianato con aminas primarias y secundarias genera 2-aminotiazolo[4,5-c]porficeno derivados con un desplazamiento concomitante en sus espectros de absorción y emisión por más de 70 nm. Esta reacción inesperada ha sido racionalizada en base a la ciclación espontánea del derivado 9-tiourea porficeno generado tras la reacción para dar lugar a un tiazoloporficeno fusionado. El alcance de dicha reacción ha sido expandido a otros derivados de porficeno como los 9-amidoporficenos. Finalmente, los porficenos isotiocianato han sido usados para el marcaje de biomoléculas y nanopartículas, dando nanoconjugados teranósticos en el infrarrojo cercano.
En segundo lugar, se ha sido estudiado el efecto de la morfología de las nanopartículas de sílice sobre la capacidad de producción y desactivación de oxígeno singlete por protoporfirina IX. La agregación del fotosensibilizador en la superficie de la nanopartícula limita la producción de oxígeno singlete. Por otro lado, a medida que aumenta la porosidad del nanomaterial es posible detectar distintas poblaciones de oxígeno singlete; una de ellas capaz de escapar de la superficie de las nanopartículas y decaer en el disolvente mientras que la otra se mantiene atrapada dentro de los poros de sílice. Los resultados revelan que controlar el grado de agregación del fotosensibilizador y su localización en la red de sílice son factores críticos a tener en cuenta en la preparación de materiales nanoporosos para liberación de oxígeno singlete.
Finalmente se han diseñado y estudiado fotosensibilizadores plasmónicos capaces de aumentar la producción y el decaimiento radiante del oxígeno singlete. Mediante técnicas de espectroscopia estacionaria y resuelta en el tiempo se demuestra que el núcleo de plata ejerce un efecto dual mediante la absorción incrementada de luz y el aumento del decaimiento radiante del oxígeno singlete, lo que se traduce en un mayor aumento de su fosforescencia. Además se demuestra que el aumento en la producción y en decaimiento radiante del oxígeno singlete depende enormemente de la proximidad del fotosensibilizador a la nanopartícula plasmónica. Así, se han identificado 3 regímenes distintos a medida que el fotosensibilizador se aleja de la nanoestructura plasmónica, situándose el máximo factor de aumento a distancias entre 10 y 20 nm del núcleo metálico. Adicionalmente, las nanopartículas plasmónicas se han usado en bacterias Gram-positivas y Gram-negativas, observando un aumento tanto de su actividad antimicrobiana como en el límite de detección de oxígeno singlete.<br>Different new molecular, bio- and nano-engineered approaches to enhance the photosensitization and detection of singlet oxygen in biological media are reported in this thesis.
First, a novel fluoro-chromogenic click reaction for the labeling of proteins and nanoparticles with porphycene derivatives is presented. Reaction of porphycene isothiocyanate with primary and secondary amines yields 2-aminothiazolo[4,5-c]porphycene derivatives with a concomitant red-shift of their absorption and fluorescence emission spectra by more than 70 nm. This unexpected reaction has been explained on the grounds of a spontaneous cyclization of the initially-formed 9-thiourea porphycene derivative onto a fused thiazoloporphycene and its scope has been expanded to other porphycene derivatives such as 9-amidoporphycenes. Furthermore, porphycene isothiocyanates have been used to label biomolecules and nanoparticles yielding near-infrared theranostic nanoconjugates.
Secondly, the role of the morphology of silica nanoparticles onto the production and deactivation of singlet oxygen by protoporphyrin IX has been investigated. Aggregation of the photosensitizer onto the surface of the nanoparticle limits the production of singlet oxygen. In addition, as the porosity of the nanomaterial increases, different populations of singlet oxygen can be detected; one population is able to escape from the nanoparticle surface and decay in the bulk solvent while the other is trapped inside the silica pores. Results reveal that controlling the aggregation state of the photosensitizer and its location is of crucial importance when preparing nanoporous materials for singlet oxygen delivery.
Finally, plasmonic photosensitizers capable of boosting the production and radiative decay of single oxygen have been designed and studied. Via time-resolved and steady state spectroscopic techniques, we demonstrate the silver core exerts a dual role of enhancing both the production of singlet oxygen, through enhanced absorption of light, and its radiative decay, which in turn boosts singlet oxygen phosphorescence emission to a greater extent. Furthermore, we show both the enhancement of the production and the emission of singlet oxygen to be dependent on proximity to the plasmonic nanostructure. Three distinct regimes have been identified as the photosensitizer moves apart the plasmonic nanostructure, with greater enhancement at distances between 10 and 20 nm. Moreover, hybrid plasmonic nanoparticles can be delivered to both Gram-positive and Gram-negative bacteria boosting both photoantibacterial activity and detection limit of singlet oxygen in cells.
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Chiang, Ai-Ping, and 江愛蘋. "Living (Rose Bengal Stained) Benthic Foraminifera in Sediments off the Southwest Taiwan." Thesis, 2004. http://ndltd.ncl.edu.tw/handle/17063201762284296625.
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碩士<br>國立中山大學<br>海洋地質及化學研究所<br>92<br>The objective for this study was to provide the insight into the link between benthic foraminiferal assemblages and the surrounding environment. Stained sediment samples were collected from the continental shelf and slope off the southwest Taiwan, including the Kao-ping Submarine Canyon. In addition to faunal census, total organic carbon (TOC), carbonate, and coarse fraction of the sediments were also measured. Nevertheless, the downcore record of the excess 210Pb from selected sites offers the constraint for stratigraphy time frame for discussion.
The benthic foraminiferal assemblages were analyzed by statistics. Clusters analysis shows that all species present in this study could be divided into two groupings. One is those distributed in outer shelf and the other is those found in the inner shelf of the southwest Taiwan. Different from previous studies, the spatial distribution of stained benthic foraminifera seems not to be related with TOC contents in the sediment and water depth. Both the diversity index and Eqitability show that sites inside of the canyon have lower values. The higher Living/Total ratios and lower dead tests at the head of Kao-ping Submarine Canyon than adjacent area might be the effect of migration. Furthermore, the species within the canyon are similar to the southern and northern continental shelf. These findings indicate that the spatial distribution of benthic forams within canyon might be the effect of transport, which could result from the complex interaction between tides and currents.
Augmented with the profiles of excess 210Pb, the temporal variation of benthic foraminifera was revealed. Generally there is a progressive decrease in the abundance of Ammonia sp.. It is possible that the diminishing trend was caused by the increase of anthropogenic activity for the last 30 years.
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Chen, Ya-Ling, and 陳雅鈴. "The Study of Picosecond and Nanosecond Nonlinear Optical Properties in Rose Bengal Solution." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/80391084863261801699.
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碩士<br>國立中正大學<br>物理所<br>95<br>In this study we use single picosecond (19ps) and single nanosecond (2.8ns) pulses as the light sources of Z-scan technique to investigate the nonlinear optical properties of Rose Bengal (RB) solution wherein we change the energy and repetition rate of laser pulses to do these experiments. The results in these two regimes show that RB/methanol solutions show saturable absorption property and positive lensing effect. The picosecond nonlinear absorption is attributed to the cascading one photon electronic transitions in singlet manifold because the pulse duration is shorter than the relaxation time from the first excited state of singlet manifold (S1) to the triplet state (T1), but the nanosecond nonlinear absorption involves the electronic transitions in both singlet and triplet manifolds. In the picosecond regime, because the pulse duration is shorter than the local thermal equilibrium time, the nonlinear refraction arises from electronic transitions and Kerr effect. On the other hand, in the nanosecond regime, because the pulse duration is longer than the local thermal equilibrium time but shorter than the time of acoustic wave to propagate across the beam cross section, the nonlinear refraction results from electronic transitions, Kerr effect and transient thermal lensing effect.
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Li, Chia-Jung, and 李佳蓉. "Rose bengal-conjugated chitosan-Ag nanoparticles as antibacterial agents under LED light exposure." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/12040245997125537480.
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碩士<br>國立臺灣大學<br>化學工程學研究所<br>98<br>The evolving of new resistant strains of bacteria to current antibiotics has become a serious problem; therefore, there is a strong incentive to develop new anti-microbial strategies for reducing microbial contamination. In this study, a light-activated antimicrobial agent tagged with a biopolymer was used to incorporate with silver nanoparticles (Ag NPs) as a potential antimicrobial approach when exposed to visible light. First, chitosan (CS) was conjugated with rose bengal (RB), a well-known photosensitizer for photodynamic therapy (PDT). Then RB-CS was further used as the stabilizing agent in the synthesis of Ag NP via chemical reduction process. Three different amounts of RB grafted on chitosan (0.0895, 0.1937, 0.7118 μg RB/mg chitosan) were prepared for the fabrication of Ag NPs. Since the absorption peak of RB at 556 nm was much lower than the absorbance of Ag NPs, the UV-Vis absorption spectrum of RB-CS/Ag NPs didn’t reveal a significant peak at 556 nm. The result of dynamic light scattering analysis showed that RB-CS/Ag NPs had an average size of 7.67 nm.
The antibacterial acivity of the RB-CS/Ag NPs was tested against Gram-negative E. coli exposed with light emitting diode (LED) light irradiation. The effect of the RB-CS/Ag NPs on the growth of E. coli was investigated by monitoring culture turbidity. After LED light exposure, singlet oxygen sensor green (SOSG) reagent was employed to detect singlet oxygen generation. The amount of singlet oxygen generated from RB-CS/Ag NPs was ≈ 1.4 fold higher than the corresponding RB only produced. Metal enhanced singlet oxygen generation was observed. Our results revealed increasing concentration of RB-CS/Ag NPs led to more singlet oxygen generation, with a fixed concentration of RB-CS/Ag NP. The more RB was grafted, the more singlet oxygen was detected. Without LED irradiation, the antibacterial effect of RB-CS/Ag NPs and Ag NPs were about the same. It is speculated that the generation of singlet oxygen enhances the antibacterial activity of RB-CS/Ag NPs. Under 26 mW/cm2 LED light exposure for 615 sec (i.e., 16 J/cm2) , 100 μg/ml RB-CS/Ag NPs were capable of inactivating growth of E. coli to a certain extent. According to cell growth profiles, the lag phase of the treated bacteria exhibited a prolonged feature as compared to untreated bacteria. Growth was completely inhibited when bacteria were treated with 200 μg/ml RB-CS/Ag NPs. These results suggest under LED light irradiation RB-CS/Ag NPs can inhibit bacterial growth through the combined RB-associated singlet oxygen generation, Ag NP-induced inactivation and CS-triggered antimicrobial activity.
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Yang, Yun-Ching, and 楊韻靜. "Combination of Intralesional Rose Bengal Injection and Orthovoltage Radiation Therapy for Canine Cancer Treatment." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/45204413242265322174.
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Lin, Juei-Chun, and 林芮君. "Living (Rose Bengal Stained) Benthic Foraminifera in Sediments off the Southwestern Taiwan and Dongsha Atoll." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/37630570995238701415.
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碩士<br>國立中山大學<br>海洋地質及化學研究所<br>99<br>The subject of this study was to investigate the species composition and spatial distribution pastern of iving (Rose Bengal stained) benthic foraminifera in sediment surface samples (0-1 cm) off the Southwestern Taiwan and Dongsha Atoll. The main objectives of this study was to document the living benthic foraminiferal assemblages off the Southwestern Taiwan and Dongsha Atoll and to examine their distribution in relation to environmental parameters.
Four benthic foraminiferal biofacies were recognized within the substrate type in Dongsha Atoll: A1 (Fine-grained) is represented by Pseudomassilina spp. - Quinqueloculina parkeri, A2 (Fine-grained) is represented by Hauerina spp. - Pseudomassilina spp., B1 (Coarse-grained) is characterised by Calcarina spp. - Quinqueloculina spp., B2 (Coarse-grained) is characterised by Amphistegina spp. - Quinqueloculina spp.
Sediment surface samples off the Southwestern Taiwan during May 2009 led to the identification of four assemblages. Assemblage A is characterised by Ammonia spp. - Bolivina spp., Assemblage B between is characterized by Asterorotalia spp. - Globobulimina spp., Assemblage C is represented by Cibicides spp. - Nummulites spp., Assemblage D is represented by Ammonia spp. - Cibicides spp.
Sediment surface samples off the Southwestern Taiwan during Nov. 2009 led to the identification of three assemblages. Assemblage A is dominated by Ammonia spp. - Cibicides spp., Assemblage B is characterised by Ammonia spp. - Bolivina spp., Assemblage C is characterised by Asterorotalia spp. - Bolivina spp.
Stained benthic foraminifera form Dongsha Atoll correlated with current wave, collected site, coarse fraction and TOC contents. Living benthic foraminifera off the Southwestern Taiwan seems not to be related with TOC contents and coarse fraction, the assemblages were found to be more related to tidal energy and lateral transport.
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葉桓溥. "Development of rose bengal-loaded multipolymeric nanoplateform as photo-responsive drug carrier for cancer therapy." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/14075967490133009409.
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碩士<br>國立清華大學<br>生醫工程與環境科學系<br>103<br>Rose bengal (RB) which exhibits high singlet oxygen (1O2) yield is a clinical promising photosensitizer in anticancer therapy. Several RB hydrophobic derivatives (e.g., acetate) have been developed to facilitate intracellular accumulation. Nanoparticles also serve as effective carriers to deliver these compounds to the tumor microenvironment, or to cross biological barriers such as cell membranes. In this study, RB molecules were encapsulated in a mixture of chitosan, polyvinyl alcohol and branched polyethylenimine (bPEI) with hydrophobic iron oxide nanoparticles through an oil-in-water emulsion method. The as-prepared multipolymeric magnetic nanoclusters displayed high water dispersibility and the cationic groups of bPEI were effective for RB loading through electrostatic interaction. In addition, triggered release of the loaded drugs also occurred simultaneously during the photodynamic reaction. The improvement of photodynamic-stimulated triggered release holds great promise in precise control of drug delivery.
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Li, Pin-Jhang, and 李品璋. "Fluorescence Enhancement of Rose Bengal by Gold Nanoparticle on Medium of Polymer and Titanium Dioxide." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/91528297300142851769.
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碩士<br>國立清華大學<br>化學系<br>102<br>We research the fluorescence enhancement of Rose Bengal on the different distance between Rose Bengal and Gold nanoparticle. In this experiment, we use confocal microscopy to measure the fluorescence lifetime of dye on the single Gold nanoparticle. The medium between molecular and Gold nanoparticle are polymer or TiO2 coating on the surface of Gold nanoparticle. In the polymer coating, we use Poly Styrene Sulfonate (PSS) and Poly Allyamine Hydrochloride (PAH) to coat on the 70 nm of Gold nanoparticle by the Layer by Layer method. We coat 1 to 7 layers, and the thickness are 1.1 nm to 7.3 nm, the average of thickness is 1.05 nm per layer. The fluorescence lifetime are bi-exponent decay. The lifetime of TAU1 are 34 ps to 60 ps, and the lifetime of TAU2 are 282 ps to 368 ps from 1 layer to 7 layers. In the TiO2 coating, we modify the surface of Gold nanoparticle, then add Titanium isopropoxide (TTIP) to coat 5 nm, 10 nm, 15 nm and 20 nm of thickness with different reaction time. And the fluorescence lifetime are also bi-exponent decay. The sample coating from 5 nm to 20 nm, which TAU1 are 24 ps to 120 ps, TAU2 are 241 ps to 672 ps. Finally, we use the experiment result and some reference to propose the simple kinetic mechanism. The fluorescence enhancement are decrease when the distance increase. The fluorescence enhancement of dye are limited on the medium of TiO2, because the excited of dye can decay by electron transfer.
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SHENG, TAN KOK, and 陳國盛. "Dynamic Effect of Fluorescence Enhancement by Gold Nanoparticles On Sulforhodamine 101 and Rose Bengal by Confocal Lifetime Imaging Microscopy." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/89442909306611851258.
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Tsuei, Raul, and 崔博欽. "Search for the appropriate photosensitizers for photodynamic therapy -Spectroscopic protesties study of Rose Bengal dissolved in various liquid solvents." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/75842307836856300507.
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碩士<br>國立中正大學<br>物理所<br>96<br>Photodynamic therapy (PDT) is a treatment that cures cancer cells using both proper organic dyes, namely the photosensitizers (photosensitizing agents), and light of adequate wavelength. A PDT involves the following processes in sequence: light absorption by the photosensitizer molecules, intermolecular energy transfer from photosensitizer molecules to the oxygen molecules, and attack of the cancer cells by the excited oxygen molecules. Efficiency of each process determines the overall treatment effect. In this paper, we investigate how the solvents, in which the photosensitizers are dissolved, affect the efficiency of each process. Particularly, we focus on the solvents with various polarities, viscosities and capabilities to from hydrogen bonds with neighboring solute molecules.
Using Rose Bengal (RB) as a photosensitizer, we dissolve it in three different solvents:acetone, tetrahydrofuran (THF), dimethylformamide (DMF). Each of the three solutions is prepared to have 5 concentrations: 、 、 、 and . We investigate absorption spectra, emission spectra, fluorescence lifetime of the 15 samples. As a result, we found that blue shift was enhanced and fluorescent life time was decreases when the hydrogen bonding strength increased. As well, the red shift and fluorescent life time increase with the increases of RB concentration.We attribute to the red shift to re-absorption of the blue edge of the fluorescent light.
To our present understanding, the hydrogen bonding is the main factor affecting the spectra of RB solutions. This infers that excited RB dissolved in solvents with stronger hydrogen, conveniently achievable water being a best example, bonding can more likely be relaxed to the triplet manifolds via intersystem crossing. This further helps the energy conversion between the photosensitizer molecules and the oxygen molecules, advantageous for PDT application.