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Zibaseresht, Ramin. "Approaches to Photoactivated Cytotoxins." Thesis, University of Canterbury. Chemistry, 2006. http://hdl.handle.net/10092/1284.
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The synthesis and coordination chemistry of eleven bridging ligands, eight of which are new compounds, are described. These ligands are all based on the tridentate terpyridyl system. The other metal ion binding sites of these ligands contain pyridine/bipyridine/pyrazole rings or amine/azamacrocycles domains. In these ligands, the two metal ion binding sites are differentiated by the number of atoms in each site, the configuration of the binding site or the types of donor atom that are present. This binding site differentiation allows to use the different coordination properties of the binding sites to control the regiochemistry of the complexation, ensuring that the correct metal ion is incorporated at the correct binding site in the ligand. Many of the complexes synthesised are mono-ruthenium(II) complexes where Ru(II) ions are situated in the terpyridyl sites of the ligands. These include heteroleptic Ru(II) complexes of the type [Ru(ttp)(L)]2+, where ttp is 4'-(p-tolyl)-2,2':6',2ʺ- terpyridine, and L is the bridging ligand. Reactions of the Ru(II) complexes with a range of metal ions including Co(III) ion have been investigated. The Ru(II) complexes can be classified into three main categories depending on the type of ligands that have been employed: (1) Ru(II) complexes which can react with Co(III) ions to form heterodinuclear Ru(II)-Co(III) complexes; (2) Ru(II) complexes which react only with Ag(I) ions and no other common metal ions that we have tried; (3) Ru(II) complexes with no detectable ability to coordinate other common metal ions. Following standard cobalt chemistry, some heterodinuclear Ru(II)-Co(III) complexes of the type [(ttp)Ru(cymt)Co(X)2]3+, where X = NO2 -, Cl-, and OH-, have been successfully prepared from the corresponding Ru(II) complexes. In these heterodinuclear complexes, anions such as NO2 -, Cl-, or OH- can be readily attached to the Co(III) ions. However, attachment of a neutral species such as en ligands to the Co(III) ions in the complexes proved to be more difficult. Reactions of heterodinuclear Ru(II)-Co(III) complexes with en ligands result in removal of the cobalt ions from the complexes. This is may be a result of a significant difference in the overall charges between the complexes with anionic and the complexes with neutral ligands (3+ vs 5+). Higher overall charge of the complexes when protonable ligands such as monodentate en are present, may destabilize the complexes even more. A combination of NMR spectroscopy, ESI-MS, UV-vis spectroscopy, elemental analysis, and X-ray crystallography has been used to characterise the ligands and their complexes. The crystal structures of one new ligand and sixteen complexes are described.
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Gallagher, Theresa Bernadette. "Application of photoactivated disinfection." Thesis, University of Brighton, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.511582.
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Atherton, Jonathan Charles Christian. "Novel photoactivated chiral auxiliaries." Thesis, University of Newcastle Upon Tyne, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.273482.
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Sitterle, Valerie B. "Photoactivated Fixation of Cartilage Tissue." Diss., Georgia Institute of Technology, 2004. http://hdl.handle.net/1853/7609.
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Cartilage repair and/or replacement is necessary for many orthopaedic conditions including fissures from blunt trauma, autograft or allograft transplantation, and replacement of focal defects with biological or synthetic constructs. In cartilage repair, initial integration between the host tissue and repair site is desirable to allow for nutrient transport, molecular deposition to enhance fixation, and eventual stress transmission across the interface. It has been postulated that effective transport and crosslinking of newly synthesized collagen molecules across a repair site may be vital to the process of integrative repair, and recent experiments have correlated collagen deposition with the strength of such repair. Other investigations have shown that enzymatic degradation of the cartilage surface may enhance integrative repair and can increase bond strength of an adhesive to cartilage.
This study explored a novel approach involving photochemical bonding of cartilage tissue samples through collagen crosslinking as a means to achieve rapid and effective initial fixation, with the goal of enhancing biological integration. Photosensitized collagen gels were first analyzed via FTIR to determine the crosslinking effects with respect to collagen type and photochemical mechanism. Using the photogellation FTIR results as a parametric guide, in vitro mechanical testing of photochemically bonded meniscal fibrocartilage and hyaline articular cartilage tissues was performed using a modified single-lap shear test. Finally, the cellular viability and bond stability of a photochemically bonded cartilage interface was evaluated over seven days of in vitro culture, where the bond strength was assessed by pushout of cores from annular defects. Results of this study have demonstrated the potential of combining enzymatic surface modification with photodynamic techniques to directly bond cartilage tissues for initial fixation.
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Woods, Stephen John. "Simulation of photoactivated bipolar devices." Thesis, University of East Anglia, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.267275.
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Gao, Junping. "Pyridinium Bisretinoids: Synthesis and Photoactivated Cytotoxicity." BYU ScholarsArchive, 2007. https://scholarsarchive.byu.edu/etd/2384.
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This thesis discusses pyridinium bisretinoid compounds (PBRs), which were prepared for two purposes: 1) to use them as standards for detection of novel fluorophores in human RPE cells, which may be involved in age-related macular degeneration (AMD), and 2) to use them in the development of a targeted and triggered drug delivery system for cancer therapy. We prepared a selection of PBRs using a one-pot biomimetic method; synthesis, mechanisms for formation, and characterization of these compounds is described. We also explored the photoreactivity of three novel PBR compounds and found that these PBRs form oxidation products under blue-light irradiation. The photoinduced cytotoxity of A2P and A2EE was examined in HL-60 cells. Results from this work suggest that the PBRs presented have the potential to be involved in AMD and to be developed into a targeted and triggered drug delivery system for cancer therapy.
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Singh, Tanya N. "Ru(II) complexes as photoactivated cisplatin analogs." Columbus, Ohio : Ohio State University, 2006. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1150391177.
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Allen, Victoria Louise. "Photoactivated lipids as modulators of membrane protein folding." Thesis, University of Bristol, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.528101.
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Tai, Hui-Chung. "Computer-aided drug design of photoactivated platinum anticancer complexes." Thesis, University of Warwick, 2011. http://wrap.warwick.ac.uk/55656/.
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Platinum(IV) complexes are usually inert and stable compounds which can be photoactive pro-drugs to produce Pt(II) species with promising anti-cancer activity. Studies of the photochemistry of Pt(IV) complexes by time-dependent density functional theory (TDDFT) and spectroscopic methods show close agreement. Broad exploration of cis/trans geometries, trans influences, the nature of the OR− and (pseudo)halogen ligands, electron-withdrawing/donating/ delocalizing substituents on the N-ligands, and intramolecular H-bonds shows that (1) the design of platinum(IV) complexes with intense bands shifted towards longer wavelengths (~330 nm) can be achieved by introducing intramolecular Hbonds involving the OH ligands and 2-hydroxyquinoline or by iodido ligands, (2) mesomeric electron-withdrawing substituents on pyridine result in low-energy absorption with significant intensity in the visible region, and (3) the distinct makeup of the molecular orbitals in electronic transitions for cis/trans-{Pt(N3)2} isomers result in different photoproducts. In general, the comparison of the optimised geometries shows that Pt(IV) complexes with longer Pt−L bonds are more likely to undergo photoreduction with longer-wavelength light. Complex trans, trans, trans-[Pt(N3)2(OH)2(NH3)(4-nitropyridine)] was first synthesised. The experimental UV-Vis spectrum in aqueous solution correlates well with the intense band in the computed spectrum whereas the overlay in the low-energy absorption region can be improved by a solvent model. This combined computational and experimental study shows that TDDFT can be a design tool to tune the coordination environment for optimizing photoactive Pt(IV) compounds as anticancer agents without immediate need for synthesis. Additionally, molecular modeling is used to study DNA distortions induced by binding metal-containing fragments derived from cisdiamminodichloroplatinum( II) (cisplatin) and a new class of photoactive platinum anticancer drugs. Ligand field molecular mechanics (LFMM) parameters for Pt– guanine interactions are derived and validated against a range of experimental structures from the Cambridge Structural Database, published quantum mechanics/molecular mechanics (QM/MM) structures of model Pt-DNA systems and additional DFT studies. LFMM gives a good description of the local Ptguanine coordination at a fraction of the computational cost of QM/MM methods. The force field is then used to develop protocols for ligand field molecular dynamics (LFMD) simulations using experimentally characterised bifunctional DNA adducts involving both an intra- and an interstrand crosslink of cisplatin as a prelude to studying the interaction of trans-{Pt(py)2}2+ (P, py = pyridine), the major photoproduct of the novel platinum(IV) complex trans,trans,trans- [Pt(N3)2(OH)2(py)2] (17), with the DNA duplex dodecamer, d(C1C2T3C4T5C6G7T8C9T10C11C12)• d(G13G14A15G16A17C18G19A20G21A22G23G24). Based on the observed formation of a trans species when 17 is photoreduced in the presence of 5’-guanosine monophosphate plus the major-groove binding mode of the monofunctional complex cis-{Pt(NH3)2(py)}2+, P is proposed to coordinate to G7 and G19. This P-DNA adduct has a widened minor groove at one end of the platinated site and deepened minor groove at the opposite end, and exhibits a global bend of ~67° and an unwinding of ~20°. Brabec et al. subsequently demonstrated experimentally that such interstrand GG crosslinks can form as a result of the photoactivation of 17 in the presence of DNA. Such cross-links offer possibilities for specific protein–DNA interactions and suggest possible mechanisms to explain the high potency of this photoactivated complex.
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Abtahi, Seyyed Mohammad Hossein. "Synthesis and characterization of metallic nanoparticles with photoactivated surface chemistries." Thesis, Virginia Tech, 2013. http://hdl.handle.net/10919/78081.
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During recent decades metallic nanoparticles have been found very interesting due to their unique characteristics which make them suitable for different applications. In this research, for the very first time, we tried to perform selective surface photo activation chemistry on the targeted facets of nanoparticles while they are in suspension. This technique enabled us to form desired assemblies of nanoparticles. We focused on elongated shaped gold nanorod due to its unique surface plasmon resonance and probable biomedical applications. In this research we formed a dumbbell shape assembly of nanoparticles in suspension. A probable application for these assemblies can be in vivo imaging. Initially, we reproduced gold nanorods using existing techniques in prior papers and optimized them according to our research needs. A low rpm centrifugal separation technique was developed to efficiently separate synthesized gold nanorods from other shapes. Several characterization techniques were utilized to characterize nanoparticles at each step including UV-absorbance, zeta potential, and dynamic light scattering. Different generations of oligomers were synthesized to be used as gold nanorods coating, and each coating was tested and characterized using appropriate techniques. Our two-step coating replacement method using one of these photocleavable oligomers enabled us to achieve, for the very first time, selective UV photo activation of gold nanorod tips. The photo activated tips were then exposed to oppositely charged gold nanospheres to form dumbbell shape assemblies of gold nanorods and nanospheres. Furthermore, dumbbell shape assembly of nanoparticles was investigated and characterized.Master of Science
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Etheridge, Thomas James. "Application of photoactivated localisation microscopy to visualising eukaryotic DNA replication processes." Thesis, University of Sussex, 2016. http://sro.sussex.ac.uk/id/eprint/60404/.
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DNA replication is a crucial process that ensures duplication of the genome prior to cellular division. The fidelity of this process is of upmost importance for ensuring genomic stability and the integrity of subsequent generations. Obstruction of the replication machinery by DNA damage, protein barriers or other impediments can cause replication stress, a phenotype often observed in cancer cells. Studying the underlying molecular mechanisms of DNA replication and the repair processes involved during replication arrest is thus critical to ensure a complete understanding of the process and the role it plays in cancer development and progression. A key technique used to study DNA replication and repair proteins is fluorescence microscopy, which allows researchers to visualise the expression and spatial organisation of cellular components. Until recently, the information that could be extracted from fluorescence images was restricted by limited resolution, a consequence of the diffraction of light. Recent advancements in fluorescence microscopy have yielded techniques that can break this diffraction barrier and achieve nanometre scale resolution. One such technique is Photoactivated Localisation Microscopy (PALM), which relies on the detection and high precision localisation of single fluorescent molecules. The work presented in this thesis outlines the development of an adaptation to PALM that can be used to study the chromatin association of proteins inside unfixed cells. This technique was subsequently used to study the role of ubiquitination of the replication-sliding clamp during unperturbed DNA synthesis and characterise the global DNA binding of the Smc5/6 complex during replication stress.
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Capadona, Lynn A. "Photoactivated Fluorescence from Small Silver Nanoclusters and Their Relation to Raman Spectroscopy." Diss., Georgia Institute of Technology, 2004. http://hdl.handle.net/1853/5117.
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Photoactivated fluorescence from individual silver nanoclusters ranging in size from 2 8 atoms has been demonstrated at room temperature. The optical properties of such clusters are far superior to those of fluorescence dyes with absorption cross sections ~50 times stronger than those of even the best organic dyes. The strong oscillator strengths produced from such nanoclusters has been shown to yield comparable enhancement factors in the surface-enhanced Raman spectroscopy (SERS) process to those observed in the presence of a plasmon- supporting nanoparticle. Raman transitions are in fact so strong that antistokes scattering is also observable on a single molecule (SM) level marking the first true demonstration of SM-SERS to date. Capable of generating true scaffold specific Raman scattering on the single molecule level, the combination of fluorescence from the small nanoclusters and strong observed Raman signals in the absence of a nanoparticle strongly indicate a chemical or charge transfer SERS enhancement mechanism.
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Presa, i. Rodríguez Andreu. "Diarylethene-based Pt(II) molecular switches: a novel approch to photoactivated chemotherapy." Doctoral thesis, Universitat de Barcelona, 2016. http://hdl.handle.net/10803/400875.
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The photoactivation of metal complexes with potential anticancer activity is a hot topic of current research, as it may lead to the development of more selective and efficient drugs. Photoactivated chemotherapy (PACT) with coordination compounds is usually based on photochemical processes taking place at the metal center. In contrast, an innovative ligand-mediated photoactivation approach that exploits the outstanding photochemical properties of diarylethenes has been developed in the present PhD thesis.
Platinum(II) complexes from dithienylcyclopentene-based photoswitchable ligands have been designed and prepared. These systems exhibit two thermally stable, interconvertible photoisomeric forms, which present clearly distinct properties. The photochemical behavior of all ligands and metal complexes has been examined by means of 1H NMR and UV-Vis spectroscopies, and a number of crystal structures have been determined.
Additionally, DFT calculations have been performed to analyze the effect produced by the attachment of different metal-binding units on the photochemical performance of the diarylethene synthon.
Subsequently, the interaction of each photoisomer of the platinum(II) complexes with DNA has been thoroughly investigated using different techniques. These studies revealed that the light-triggered transformation of these systems effectively translates into different DNA binding modes and affinities, as desired for a photoactivatable drug. The antiproliferative activity of the complexes prepared has then been evaluated through various cell viability in vitro assays, which validated the potential applications of such diarylethene-based photoswitches for the development of a new class of photochemotherapeutic metallodrugs.La fotoactivació de complexos metàl·lics amb potencial activitat antitumoral és un camp de recerca amb un interès creixent, que persegueix el desenvolupament de tractaments més selectius i eficients. Tradicionalment, la quimioteràpia fotoactivada (PACT) basada en compostos de coordinació inorgànics s'ha centrat en els processos fotoquímics que tenen lloc en el centre metàl·lic. En canvi, en aquesta tesi doctoral s'ha desenvolupat una estratègia alternativa enfocada en la fotoactivació dels lligands, aprofitant les excel·lents propietats fotoquímiques dels diariletens. Amb aquest objectiu, s'han dissenyat i preparat diferents complexos dinuclears de Pt(II) amb lligands basats en l'estructura del ditienilciclopentè. Aquestes molècules presenten dues formes fotoisomèriques interconvertibles i tèrmicament estables, que a més difereixen notablement en les seves propietats. El comportament fotoquímic dels lligands i complexos sintetitzats s'ha estudiat per mitjà d'espectroscòpia 1H RMN i UV-Vis, i d’altra banda també s'han resolt diverses estructures cristal·lines. Addicionalment, s'han emprat càlculs computacionals DFT per tal d'analitzar l'efecte sobre l'activitat fotoquímica del fragment diariletè produït per l'acoblament de diferents grups funcionals. Seguidament, s'ha investigat la interacció amb ADN de cadascun dels fotoisòmers dels complexos de Pt(II) preparats, mitjançant diferents tècniques. Els estudis realitzats han posat de manifest que la fotointerconversió d'aquest tipus de sistemes dóna lloc a diferents modes d’unió i graus d'afinitat envers l'ADN, tal i com és desitjable per un fàrmac fotoactivable. En darrer lloc, l'activitat antiproliferativa dels compostos ha estat avaluada a través de diferents assaigs cel·lulars in vitro, que han permès corroborar el gran potencial dels sistemes basats en diariletens per ser aplicats en el disseny de fàrmacs.
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Himmel, Hans-Jörg. "Generation and characterisation of some molecular compounds of the group 13 metals." Thesis, University of Oxford, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.365869.
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Ballesteros, Camilo Arturo Suarez. "Smart nanomaterials based on the photoactivated release of silver nanoparticles for bacterial control." Universidade de São Paulo, 2017. http://www.teses.usp.br/teses/disponiveis/76/76132/tde-14092017-143257/.
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Smart nanomaterials can selectively respond to a stimulus and consequently be activated in specific conditions, as a result of their interaction with electromagnetic radiation, biomolecules, pH change, etc. These nanomaterials can be produced through distinct routes and be used in artificial skin, drug delivery, and other biomedical applications. In this thesis, two smart nanosystems were developed, viz., i) nanocapsules formed by aniline (A) and chitosan (CS) (A-CS) containing silver nanoparticles (AgNPs), with an average size of 78 ± 19 nm, and ii) polycaprolactone (PCL) nanofibers, fabricated by the electrospinning technique containing AgNP into their bulk, with a diameter of 417 ± 14 nm. A novel system, based on the incorporation of the as-prepared nanocapsules onto the surface of PCL nanofibers containing AgNps (antibacterial mats), was also developed. The methodology employed avoids the direct contact of silver nanoparticles with the host and optimizes its release to the surrounding environment. The AgNPs release was triggered by exposing the nanocapsules to light at 405 nm. Consequently, the electronic energy vibration resulting from the interaction of the irradiation with the surface plasmon band (SPR) of AgNps, breaking the hydrogen bonds of the nanocapsules and releasing of AgNPs at a time of 150 s. To understand the perturbation of AgNps-Nanocapsules against bacteria, membrane models using Langmuir technique with the phospholipids 1,2-dipalmitoyl-sn-glycero-3-phospho-(1\'-rac-glycerol) (DPPG) and 1,2-dimyristoyl-sn-glycero-3-phosphoethanolamine (DMPE) were employed, which are the main components of cell membrane of Escherichia coli (E. coli). The results suggest that DPPG has more influence on the incorporation of the nanoparticles on the cell membrane. The antibacterial properties of the nanofibers/nanomaterials mats towards E. coli and Staphylococcus aureus (S. aureus) were investigated using the Agar diffusion test for 8 samples. The experiments revealed that the samples based on nanofibers/nanocapsules and irradiation presented a radius of inhibition of 2.58 ± 0.28 mm for S. aureus and 1.78 ± 0.49 mm for E. coli. This nanosystem showed to be highly interesting for biomedical applications.Nanomateriais inteligentes podem responder seletivamente a um estímulo e consequentemente ser ativados em condições específicas, como resultado da sua interação com a radiação eletromagnética, mudança do pH, campo magnético, etc. Esses materiais podem ser produzidos através de distintas rotas e utilizados em aplicações como pele artificial, liberação de fármacos, e outras aplicações biomédicas. Nessa tese, dois nanossistemas inteligentes foram desenvolvidos, a saber: i) nanocápsulas formadas por anilina (A) e quitosana (CS) (A-CS) contendo nanopartículas de prata (AgNps), com um tamanho médio de 78 ± 19 nm, e ii) nanofibras de policaprolactona (PCL), fabricadas pela técnica de eletrofiação contendo AgNps em seu interior, com diâmetro de 417 ± 14 nm. Um terceiro sistema foi desenvolvido, baseado na incorporação das nanocápsulas na superfície das nanofibras de PCL contendo AgNps (manta antibacteriana). A metodologia utilizada evita o contato direto das nanopartículas de prata com o hospedeiro e otimiza sua liberação no meio ambiente. As AgNps liberadas foram acionadas pela exposição das nanocápsulas à um fonte de luz em 405 nm. Consequentemente, a vibração da energia eletrônica resultante da interação da irradiação com a banda plasmônica de superfície (SPR) das AgNps, quebra as ligações de hidrogênio da nanocápsula e libera as AgNps no meio em um tempo de 150 s. Para entender a perturbação das AgNps-nanocapsulas contra as bactérias, modelos de membrana foram usados através da técnica de Langmuir com os fosfolipídios 1,2-dipalmitoil-sn-glicero-3- fosfo-(1\'-rac-glicerol) (DPPG) and 1,2-dimiristoil-sn-glicero-3-fosfoetanolamina (DMPE), que são os principais componentes da membrana celular de Escherichia coli (E. coli). Os resultados sugerem que DPPG tem mais influência na incorporação das nanopartículas na membrana celular. As propriedades antibacterianas das mantas de nanofibras/nanomateriais contra E. coli e Staphylococus aureus (S. aureus) foram investigadas usando o teste de difusão Agar em 8 grupos, o qual revelou que o grupo contendo a nanofibra/nanocapsula e irradiação apresentou um raio de inibição de 2.58 ± 0.28 mm para S. aureus e 1.78 ± 0.49 mm para E. coli. Este nanossistema mostrou ser altamente interessante para aplicações biomédicas.
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Poulin, Peter Roland. "Design of a photoactivated electron gun for the ultrafast study of chemical reaction dynamics by electron diffraction." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape10/PQDD_0005/MQ40734.pdf.
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Lee, Michael. "An in vitro comparison of four photoactivated disinfection systems in the lethal photosensitisation of E. faecalis in root canals /." [St. Lucia, Qld.], 2003. http://www.library.uq.edu.au/pdfserve.php?image=thesisabs/absthe17812.pdf.
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Udwari, Daniel [Verfasser], and Thomas [Akademischer Betreuer] Oertner. "A photoactivated adenylyl cyclase as an optogenetic tool to manipulate neuronal signaling and synaptic plasticity / Daniel Udwari. Betreuer: Thomas Oertner." Hamburg : Staats- und Universitätsbibliothek Hamburg, 2016. http://d-nb.info/1098428951/34.
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Udwari, Daniel Verfasser], and Thomas G. [Akademischer Betreuer] [Oertner. "A photoactivated adenylyl cyclase as an optogenetic tool to manipulate neuronal signaling and synaptic plasticity / Daniel Udwari. Betreuer: Thomas Oertner." Hamburg : Staats- und Universitätsbibliothek Hamburg, 2016. http://nbn-resolving.de/urn:nbn:de:gbv:18-67274.
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Floc'h, Kevin. "Etude de l'organisation et de la dynamique du nucléoïde de Deinococcus radiodurans par microscopie de fluorescence avancée." Thesis, Université Grenoble Alpes (ComUE), 2019. http://www.theses.fr/2019GREAV007/document.
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Durant ce projet, nous nous sommes intéressés à une bactérie, D. radiodurans, un coque particulièrement connu pour ces extraordinaires capacités de résistance à différents facteurs de stress. Cependant, à cause de ses capacités de radiorésistance, cette bactérie a surtout été étudiée dans cette optique. Certaines caractéristiques de son cycle cellulaire restent méconnues, notamment (i) sa morphologie au cours de sa division ainsi que (ii) l’organisation et (iii) la ségrégation de son nucléoïde. Ces méconnaissances touchent aussi de façon plus générale toutes les bactéries de types coques, notamment de par la petite taille relative des bactéries qui a été un frein pour leurs études en microscopie photonique.Le but du projet de thèse est donc de mieux comprendre comment les bactéries sont capables d’avoir un nucléoïde très compacté, mais en même temps, dynamique et restant accessible pour les différents mécanismes tels que la réplication de l’ADN, sa transcription ou sa réparation. Dans ce but, nous avons exploré l’organisation en 4D ainsi que la dynamique du nucléoïde de D. radiodurans, en fonction du cycle de vie de la bactérie, de sa phase de croissance. Afin de réaliser ces objectifs, plusieurs stratégies ont été poursuivies : (i) des timelapses en 3D par microscopie confocale (ii) l’étude dynamique du nucléoïde par FRAP et par SptPALM, et (iii) la cartographie des protéines associées au nucléoïde réalisé par microscopie de super-résolution (PALM)During this PhD work, we have studied on D. radiodurans, a coccus, known for its intriguing outstanding resistance to different stress factors. Studies on D. radiodurans have been mainly focusing on its tremendous radioresistance. 52 years after its discovery, its nucleoid organization/segregation as well as its cell morphology during its cell cycle still remain elusive. Most of our knowledge on the bacteria shape during division and on the nucleoid organization/segregation arises from the study of a small number of “model bacteria”, that are mainly rod-shaped or ovoid. In contrast, little is known on the nucleoid organization/segregation of cocci. Moreover, the small relative size of bacteria and of their nucleoids (<1µm3) has limited their studies by conventional microscopy.Thus, one of the aims of this PhD project is to contribute to a better understanding of the cell morphology and the nucleoid organization/segregation in cocci. For that matter, we explored the 4D organization and the dynamics of D. radiodurans nucleoids, as a function of the cell cycle progression and growth phase. In order to achieve the objective of this PhD, several strategies were undertaken: (i) timelapse 3D stacks by spinning confocal microscopy (ii) dynamics studies with FRAP analysis and SptPALM acquisitions, and (iii) cartographies of nucleoid associated proteins using super-resolution microscopy (PALM)
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Karathanasis, Christos [Verfasser], Mike [Akademischer Betreuer] Heilemann, Mike [Gutachter] Heilemann, and Gerhard [Gutachter] Hummer. "Quantitative photoactivated localization microscopy reveals the oligomeric state of the tumor necrosis factor receptor 1 / Christos Karathanasis ; Gutachter: Mike Heilemann, Gerhard Hummer ; Betreuer: Mike Heilemann." Frankfurt am Main : Universitätsbibliothek Johann Christian Senckenberg, 2019. http://d-nb.info/1202297951/34.
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Barrientos, Nava Juan Rene 1972. "Resistência ao micro-cisalhamento de cimentos resinosos fotoativados através de diferentes espessuras de cerâmica = Micro-shear bond strength of resin cements photoactivated through different ceramic thickness." [s.n.], 2015. http://repositorio.unicamp.br/jspui/handle/REPOSIP/288537.
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Orientador: Rafael Leonardo Xediek ConsaniDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Odontologia de Piracicaba
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Resumo: O objetivo neste estudo foi avaliar a resistência da união ao cisalhamento de cimentos resinosos fotoativados através de diferentes espessuras de cerâmica e o modo de fratura. Foram utilizados os cimentos resinosos RelyX U200 (3M ESPE) e Variolink II (Ivoclar-Vivadent). Sessenta discos de cerâmica IPS Empress Esthetic (Ivoclar-Vivadent) com 12mm de diâmetro foram separados em grupos (n=10) segundo a espessura (0,7; 1,4 e 2,0mm). A superfície dos discos foi condicionada com ácido hidrofluorídrico a 10% por 60s, lavada e seca com jato de ar por 60s. A seguir foi feita aplicação de agente silano por 60s. Uma matriz de elastômero com forma de disco com 15mm de diâmetro e 0,5mm de espessura com quatro orifícios de 1,5mm de diâmetro foi usada para delimitar a área de adesão na cerâmica. A manipulação dos cimentos resinosos foi de acordo com as instruções dos fabricantes, o material inserido nos orifícios da matriz, recoberto com tira de poliéster e lâmina de microscópio com pressão digital. A fotoativação foi realizada através do disco de cerâmica com Ultra Lume LED 5 (Ultradent) com potência de 1200 mW/cm² por 60s. Após armazenagem por 24h em água destilada a 37ºC, os corpos-de-prova foram avaliados com lupa estereoscópica para descartar aqueles com imperfeições. O teste de resistência ao cisalhamento foi conduzido em máquina de Ensaio Universal Instron (Canton, MA, USA), com velocidade de 1 mm/min e com célula de carga de 50Kg até fratura e os valores de resistência da união calculados em MPa. O modo de fratura foi analisado com lupa estereoscópica (LABOMED, Barueri, SP), com aumento de 10 vezes. Os resultados foram submetidos à análise de variância de dois fatores e teste de Tukey (5%). Os modos de fratura foram considerados em função da predominância das falhas sendo a falha coesiva em cerâmica a que prevaleceu. Os resultados mostraram que a interação entre os fatores espessura da cerâmica e cimento, e o fator espessura não foram significantes (p=0,541 e p=0,643, respectivamente), enquanto o fator cimento foi significativo (p=0,009). Pode-se concluir que o cimento Variolink II apresentou resistência de união significantemente maior que a do cimento RelyX U200
Abstract: The aim of this study was to evaluate the bond shear strength of resin cements photoactivated through different thicknesses of ceramics and the failure mode. RelyX U200 (3M ESPE) and Variolink II (Ivoclar Vivadent) resin cements were used. Sixty ceramic discs of Esthetic IPS Empress (Ivoclar-Vivadent) with 12mm diameter were divided into groups (n=10) according to their thickness (0.7; 1.4 and 2.0mm). The grounded surface was etched with 10% hydrofluoric acid for 60 seconds, rinsed and dried with compressed air for 60s. The following silane application was made for 60s. An elastomeric matrix having 15mm in diameter and 0.5mm in thickness with four holes (1.5mm in diameter) was used to define the adhesion area in the ceramic. The manipulation of the resin cements was carried out according to the manufacturers¿ instructions and inserted into the holes of the elastomer matrix, covered with plastic strip and finger pressed with a microscope slide. Light curing through ceramic was Ultra Lume LED 5 (Ultradent) with power 1200mW/cm² for 60s. After storage for 24h in distilled water at 37ºC, all resin cylinders were checked under magnification. The shear strength test was conducted in a Instron Universal Testing Machine, at cross-head speed of 1mm/min with load of 50Kg until fracture. The bond strength values were calculated (MPa). The fracture mode was analyzed using stereoscopic lens 10x (LABOMED, Barueri, SP). The results were submitted to two-way ANOVA and the means compared by Tukey¿s test (5%). Cohesive failure mode within ceramic was predominant. The results showed that the interaction between the factors and cement thickness, and the thickness factor were not statistically significant (p=0.541 and p=0.643, respectively). The cement factor was significant (p=0.009). In conclusion, the Variolink II showed significantly higher bond strength value than the RelyX U200 cement
Mestrado
Materiais Dentarios
Mestre em Materiais Dentários
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Roose, Max. "Photolibération de monoxyde d'azote dans des complexes de ruthénium nitrosyle à ligands polypyridines fonctionnalisés par des groupes fluorène ou méthoxyphényle." Thesis, Toulouse 3, 2018. http://www.theses.fr/2018TOU30189/document.
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Le monoxyde d'azote (NO•) est connu pour son rôle dans de nombreux processus biologiques et physiologiques. Il peut cependant avoir des effets antagonistes selon sa concentration dans le milieu. Le développement de sources exogènes capables de relarguer localement et quantitativement NO• est donc nécessaire pour profiter pleinement de son potentiel thérapeutique. La chimiothérapie photoactivée offre une approche intéressante qui consiste en l'irradiation de systèmes photosensibles non toxiques dans l'obscurité, mais capables de déclencher la mort cellulaire sous activation à la lumière. Cette thèse s'articule autour de trois complexes de ruthénium nitrosyle (RuNO) à ligands polypyridines, développés dans la perspective d'étudier leur comportement par excitation mono- et biphotonique. La fonctionnalisation des ligands polypyridines par des groupements riches en électrons permet d'envisager une excitation à 2 photons dans la fenêtre thérapeutique afin de traiter de manière locale des tumeurs plus profondes. Un état de l'art sur ces enjeux et cette thématique est dressé dans le premier chapitre. Dans le deuxième chapitre, une étude théorique comparative de plusieurs complexes RuNO à ligand bipyridine fonctionnalisée par des fluorènes permet de sélectionner le meilleur candidat pour la photolibération de NO•. Dans le troisième chapitre, la synthèse et la caractérisation de [Ru(terpy)(F2bpy)(NO)](PF6)3 (terpy = 2,2':6',2''-terpyridine; F2bpy = 4,4'-bis(9,9'-dibutyl-9H-fluoren-2-yl)-2,2'-bipyridine) sont décrites. Sont ensuite présentées dans le quatrième chapitre la synthèse et la caractérisation de [Ru(terpy)(MP2bpy)(NO)](PF6)3 (T0B2) et [Ru(MPterpy)(MP2bpy)(NO)](PF6)3 (T1B2), avec MP2bpy = 4,4'-bis(4-méthoxyphényl)-2,2'-bipyridine et MPterpy = 4'-(4-méthoxyphényl)-2,2':6',2''-terpyridine. Dans le cinquième chapitre, les propriétés photophysiques de [Ru(terpy)(F2bpy)(NO)](PF6)3 sous excitation à un photon et à deux photons sont étudiées, la libération de NO• est mise en évidence (détermination du rendement quantique фNO et de la section efficace σ) et le photoproduit est caractérisé. Le comportement des complexes T0B2 et T1B2 sous irradiation monophotonique est étudié dans le sixième chapitre, à travers la photolibération de NO•, la caractérisation de leur photoproduit et la détermination de фNONitric oxide (NO•) is known for its role in many biological and physiological processes. Nonetheless its effects are opposite according to the concentration in the media. The development of exogeneous sources able to release locally and quantitatively NO• is therefore necessary to fully benefit from its therapeutic potential. Photoactivated chemotherapy offers an interesting approach consisting in the irradiation of non toxic photoreactive systems in the dark, but able to trigger cell death when irradiated with light. This thesis is based on three ruthenium nitrosyl complexes (RuNO) with polypyridyl ligands, developed in view of studying their behavior under mono- and biphotonic excitation. The functionalization of polypyridyl ligands by electron-rich groups enables to consider a two-photon excitation in the therapeutic window in order to access deeper tumors locally. A state of art on those stakes and on this theme is addressed in the first chapter. In the second chapter, a comparative theoretical study of several RuNO complexes with a bipyridine ligand functionalized with fluorene enables to select the best candidate for NO• photorelease. In the third chapter, the synthesis and the characterization of [Ru(terpy)(F2bpy)(NO)](PF6)3 (terpy = 2,2':6',2''-terpyridine; F2bpy = 4,4'-bis(9,9'-dibutyl-9H-fluoren-2-yl)-2,2'-bipyridine) are detailed. In the fourth chapter are presented the synthesis and characterization of [Ru(terpy)(MP2bpy)(NO)](PF6)3 (T0B2) and [Ru(MPterpy)(MP2bpy)(NO)](PF6)3 (T1B2), with MP2bpy = 4,4'-bis(4-methoxyphenyl)-2,2'-bipyridine et MPterpy = 4'-(4-methoxyphenyl)-2,2':6',2''-terpyridine. In the fifth chapter, the photophysical properties of [Ru(terpy)(F2bpy)(NO)](PF6)3 under one-photon and two-photon excitation are studied, NO• release is demonstrated (determination of the quantum yield фNO and the cross section σ) and the photoproduct is characterized. The behavior of T0B2 and T1B2 under monophotonic irradiation is described in the sixth chapter, through the photorelease of NO•, the characterization of their photoproduct, and the determination of фNO
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Lima, Michele de Oliveira 1991. "Influência do preaquecimento nas propriedades físicas de agentes cimentantes fotoativados através de diferentes espessuras de cerâmica = Influence of pre-heating on the physical properties of luting agents photoactivated through different ceramic thicknesses." [s.n.], 2015. http://repositorio.unicamp.br/jspui/handle/REPOSIP/288862.
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Orientador: Flávio Henrique Baggio AguiarDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Odontologia de Piracicaba
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Resumo: O propósito deste estudo "in vitro" foi avaliar a influência do preaquecimento e ativação de agentes de fixação através de blocos cerâmicos sobre suas propriedades físicas. Para tanto, os agentes cimentantes RelyX Arc (RXA; 3M/ESPE), RelyX Ultimate (RXU; 3M/ESPE), RelyX Veneer (RXV; 3M/ESPE) e Filtek Z350 Flow (FLK; 3M/ESPE) foram manipulados com diferentes temperaturas (23ºC ou 54ºC), inseridos em matrizes de silicone específicas (cilíndricas: 5x0,5mm ou ampulheta: 0,5mm de espessura, 8mm de comprimento, 4mm de largura e 1,5mm de constrição, de acordo com a metodologia dos testes realizados) e fotoativados sob discos cerâmicos de dissilicato de lítio (IPS e.max; Ivoclar Vivadent, Barueri, SP, Brasil), cor A2, nas espessuras de 0,75mm ou 1,5mm.?A fotoativação foi realizada posicionando a extremidade do aparelho fotoativador sobre o disco cerâmico, para tal foi utilizado o LED Bluephase 16i (Vivadent, B?rs, Austria), com irradiância de 1519 mW/cm², por 40 segundos. Foram confeccionadas 128 amostras cilindricas (n=8) e realizados os testes de grau de conversão (GC) por meio da espectroscopia FT-IR. Estes mesmos espécimes foram levados ao microdurômetro para a mensuração da dureza Knoop (DK) na superfície de topo e logo após, foram imersos em solução de álcool absoluto por 24 h, e então foi realizada uma nova leitura de DK para a obtenção do percentual de redução de dureza e mensuração indireta da densidade de ligações cruzadas (DLC) dos materiais. Foram confeccionadas novas amostras em formato de ampulheta (n=8) que foram utilizadas para o teste de resistência coesiva à tração (RCT), realizado em máquina de ensaio universal. Para os testes de sorção de água (SA) e solubilidade (S) dos agentes de fixação, foram necessários novos espécimes cilíndricos (n=8) que foram pesados em balança analítica até obtenção de massa constante. Os dados foram analisados utilizando-se ANOVA três fatores e teste de tukey (?=0,05). Com relação às espessuras de cerâmica testadas, a menor espessura de cerâmica proporcionou maiores valores de DK (p=0.027). A menor temperatura (23°C) proporcionou maiores valores de SA (p=0.0229) e S (p=0.0257). Também houve diferença estatística para o fator cimento, sendo que para GC, RXA apresentou os maiores valores, seguido dos agentes cimentantes RXV, RXU e FLK. Para o teste de DK e DLC, RXU apresentou os maiores valores, seguido de RXA, RXV e FLK. Para o teste de RCT, RXA apresentou os maiores valores, seguido por RXV, RXU e FLK. Para SA e S, RXV apresentou os maiores valores, seguido por RXA, RXU e FLK. Pode-se concluir que o preaquecimento diminuiu nos resultados de sorção de água e solubilidade; a maior espessura de cerâmica diminuiu apenas a microdureza superficial, e que as propriedades físicas dos materiais são dependentes da composição dos mesmos
Abstract: The purpose of this "in vitro" study was to evaluate the influence of preheating on the physical properties of a luting agent photoactivated through ceramic discs. The cements: RelyX Arc (RXA, 3M / ESPE), RelyX Ultimate (RXU; 3M / ESPE), RelyX Veneer (RXV; 3M / ESPE), and Filtek Z350 Flow (FLK; 3M / ESPE) were manipulated using different temperatures (23°C or 54°C), inserted in specific silicone matrices (cylindrical: 5x0.5mm or hourglass: thickness 0.5 mm, 8 mm in length, 4mm wide and a 1.5mm constriction, according to the methodology of testing) and photoactived under lithium disilicate ceramic discs (IPS e.max, Ivoclar Vivadent, Barueri, SP, Brazil) color A2, in thicknesses of 0.75 mm or 1.5 mm. Photoactivation was carried out by positioning the end of the curing unit on the ceramic disk. A Bluephase 16i (Vivadent, B?rs, Austria), with an irradiance of 1519 mW / cm2, was used for 40 seconds to cure the specimens. One hundred twenty-eight cylindrical samples were prepared (n=8) and the degree of conversion tests (DC) were performed using FT-IR spectroscopy. The samples were taken to a Knoop hardness tester (KHN) for microhardness testing on the top surface. After the initial testing, the specimens were dipped in absolute ethanol solution for 24 h, and then a new KHN reading was performed to obtain the hardness reduction percentage and the crosslink density (CLD) indirect measurement of the material. New samples were prepared with an hourglass shape (n=8) and were used for the ultimate tensile strength (UTS) testing, performed in a universal testing machine. For the water sorption test (WS) and solubility (S) of the luting agents, new cylindrical specimens (n=8) were required which were weighed on an analytical balance until a constant mass was obtained. The data was analyzed using three-way ANOVA and Tukey¿s test (?=0.05). Regarding the tested ceramic thicknesses, the thinnest ceramic gave higher values of KHN (p=0.027). The lowest temperature (23°C) gave higher S (p=0.0257) and WS (p=0.0229) values. There was also a statistically significant difference for cement factor, where RXA showed the highest values for DC, followed by RXV, RXU and FLK. For the KHN and CLD tests, RXU showed the highest values, followed by RXA, RXV and FLK. For the UTS test, RXA showed the highest values, followed by RXV, RXU and FLK. For WS and S, RXV showed the highest values, followed by RXA, RXU and FLK. It can be concluded that pre-heating decreased the results of water sorption and solubility; the biggest ceramic thickness decreased only superficial microhardness, and the physical properties of the material are dependent on the composition thereof
Mestrado
Dentística
Mestra em Clínica Odontológica
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De, la Cadena Pérez-Gallardo Alejandro [Verfasser], Benjamin [Gutachter] Dietzek, and Thomas Wilhelm [Gutachter] Bocklitz. "Development and characterization of a microscope based on pump-probe spectroscopy : a valuable tool for the study of photoactivated drugs in cellulo / Alejandro De la Cadena Pérez-Gallardo ; Gutachter: Benjamin Dietzek, Thomas Wilhelm Bocklitz." Jena : Friedrich-Schiller-Universität Jena, 2018. http://d-nb.info/1207273309/34.
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Ambrosini, Veronica. "Antimicrobial Photodynamic treatment as pest management. A study of the effects of photoactivated TPPS and Chlorophyllin on the fungus pathogen Botrytis cinerea, and on two plant models : Grapevine (Vitis vinifera) and Potato (Solanum tuberosum)." Thesis, Limoges, 2020. http://aurore.unilim.fr/theses/nxfile/default/990008db-1196-4108-9048-ba6f3d9a56c4/blobholder:0/2020LIMO0073.pdf.
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Un des problèmes majeurs de l'agriculture reste la lutte contre les agents pathogènes, en particulier les champignons. Depuis les années 60, l'utilisation de quantités phénoménales de pesticides, pour garantir les rendements des cultures, a provoqué́ une pollution désastreuse de l'environnement, une perte de la biodiversité et le développement de pathogènes multi-résistants. Les pratiques agricoles doivent donc devenir plus respectueuses de l'environnement tout en restant optimales. Le traitement photodynamique antimicrobien (APDT) est un traitement alternatif envisagé dans la lutte contre les microorganismes pathogènes, sans effet sur les plantes de culture et sur l'environnement voir la santé humaine. Dans l’intention de développer cette approche, deux photosensibilisateurs (PS) : une porphyrine anionique (TPPS) et une chlorine (la Chlorophylline) ont été testés sur un champignon pathogène (Botrytis cinerea) et deux de ses cibles : la vigne (Vitis vinifera) et la pomme de terre (Solanum tuberosum). Nous avons montré que TPPS même à très faible concentration inhibait la croissance du mycélium de B. cinerea sans pour autant altérer le développement des jeunes plants de vigne cultivés in vitro. Des résultats très similaires ont aussi été obtenus avec la Chlorophylline (Chl), molécule naturelle. TPPS et Chl semblent donc de très bons candidats pour une approche APDT. Cependant, dans le but d’une approche éco-responsable, nous privilégions plutôt Chl molécule naturelle contre TPPS, molécule de synthèse. En conclusion, les résultats obtenus tout au long de ces travaux de thèse sont réellement encourageants et nous permettent de défendre l’APDT comme stratégie agricole d’avenir et surtout éco-friendlyNowadays, one of the major problems in agriculture remains the struggle against pathogens, especially fungi. In the last 60 years, the use of large amounts of pesticides to increase crop yield caused environmental pollution, loss of biodiversity, and the development of multi-resistant plant pathogens. Now, more than ever, agriculture practises must become environmentally friendly and thus, new strategies to improve agriculture, without side effects for the environment and human health, need to be developed. Antimicrobial photodynamic treatment (APDT) has emerged as an alternative treatment that can be envisaged in agronomic practices to fight against microorganisms, without harming plants. To develop this approach on complex living systems such as grapevine and potato, hosts of the fungus pathogen Botrytis cinerea and two photosensitizers were taken into consideration: an anionic porphyrin (TPPS) and a natural chlorin Chlorophyllin (Chl). More specifically, an extensive work was conducted using photoactivated TPPS. TPPS was very effectively inhibit Botrytis cinerea development and it did not cause any phenotypical or biochemical alterations of the grapevine varieties (Merlot, Chardonnay and Sauvignon). In the potato varieties, while there were alterations in its growth and development, the plants were able to defend themselves. Furthermore, in order to find a new eco-friendly solution that is more suitable for a large range of plants we tested a natural PS: the chlorophyllin (Chl). Surprisingly, Chl was able to inhibit Botrytis cinerea mycelium growth without disturbing neither potato nor grapevine plantlet growth. In conclusion, these preliminary studies based on the use of Chl suggest that the development of a safe but efficient APDT approach in agriculture may no longer be a dream
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Jacq, Maxime. "Etude de la morphogénèse et de la division chez Streptococcus pneumoniae." Thesis, Université Grenoble Alpes (ComUE), 2016. http://www.theses.fr/2016GREAV008/document.
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La division bactérienne résulte de la constriction de la membrane, menée par la protéine du cytosquelette FtsZ, et de l’expansion et du remodelage de la paroi, réalisés par des synthétases et des hydrolases de la paroi. La coordination de ces processus au sein d’un macrocomplexe protéique, le divisome, est nécessaire au maintien de la forme et de l’intégrité bactérienne. J’ai étudié deux aspects importants de ce mécanisme de coordination chez le pathogène humain Streptococcus pneumoniae. J’ai déterminé in vivo la nanostructure de la protéine FtsZ en développant l’utilisation du PALM (PhotoActivated Localization Microscopy)chez le pneumocoque. Cette technique, basée sur la détection de molécules uniques et permettant une résolution de 20-40 nm, a révélé des aspects inattendus (dimensions, amas, sous-structures) de l’architecture de l’anneau de FtsZ au cours du cycle cellulaire. En parallèle, j’ai étudié le rôle de l’hydrolase Pmp23 par génétique, biochimie et microscopie à fluorescence. Mon travail a montré que Pmp23 est requise pour la stabilité des macrostructures du divisome du pneumocoque, révélant une nouvelle connexion entre le métabolisme de la paroi et la division cellulaireBacterial division results from the combination of membrane constriction, driven by the cytoskeletal protein FtsZ, with cell wall expansion and remodeling, performed by cell wall synthases and hydrolases. Coordination of these processes within a large protein complex known as the divisome ensures cell integrity and maintenance of cell shape. I have investigated two important aspects of this coordination mechanism in the human pathogen Streptococcus pneumoniae. I determined the in vivo nanostructure of the divisome scaffolding protein FtsZ by developing the use of PhotoActivated Localization Microscopy (PALM) in the pneumococcus. PALM, which is based on the detection of single fluorescent labels and allows 20-40 nm resolution, has revealed unexpected features (dimensions, clusters, new substructures) of the FtsZ-ring architecture along the cell cycle. In parallel, I studied the role of the cell wall hydrolase Pmp23 using genetics, biochemistry and fluorescence microscopy. My work has shown that Pmp23 is required for the stability of divisome macrostructures in the pneumococcal cell, revealing a new connection between cell wall metabolism and cell division
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Mathes, Tilo. "Photochemie und Signaltransduktion von Blaulichtrezeptorproteinen aus photosynthetisierenden Mikroorganismen." Doctoral thesis, Humboldt-Universität zu Berlin, Mathematisch-Naturwissenschaftliche Fakultät I, 2008. http://dx.doi.org/10.18452/15692.
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Die lichtaktivierte Kinase Phototropin aus Chlamydomonas reinhardtii, die photoaktivierte Adenylatcyclase (PAC) aus Euglena gracilis und das BLUF-Protein Slr1694 aus Synechocystis sp. PCC 6803 wurden in Hinblick auf die molekularen Details der primären photochemischen Prozesse sowie der Signalweiterleitung untersucht. Phototropin wurde mit Hilfe von Arginin aus Escherichia coli in Milligramm Mengen isoliert. Ohne Arginin wurde E. coli cAMP Rezeptorprotein assoziiert aufgefunden, welches eine hohe Homologie zu einer cAMP aktivierten Kinase aus C. reinhardtii besitzt. Volllängen Phototropin bildet wie einzelne LOV-Domänenkonstrukte ohne Kinasedomäne den Flavin-Triplettzustand und das kovalente Cysteinyl-Addukt. Der Zerfall des Signalzustandes ist in Anwesenheit von ATP beschleunigt und deutet auf Photorezeptor-Kinase Interaktion hin. Strukturelle Änderungen in der Kinasedomäne wurden durch FTIR-Differenzspektroskopie gezeigt. Über ELDOR-Spektroskopie wurde der Abstand der Photorezeptordomänen auf etwa 25 Angstrom bestimmt. Mutationen in Slr1694 an S28, N31 und W91 zeigten keine konservierten Einfluss auf die Dynamik des Signalzustands. Die Entfernung der Seitenkette von S28 führte zu einer 15 nm Rotverschiebung des Absorptionsspektrums aufgrund veränderter Wasserstoffbrückenkoordination des Kofaktors. Die Einführung von positiv geladenen Seitenketten an Stelle von N31 erhöhte die Kofaktorbindung von phosphorylierten Flavinen. Künstliche Kofaktoren wie Roseoflavin konnten in Slr1694 durch Koexpression eines prokaryotischen Flavintransporters erreicht werden. Die Rolle von M152 in PAC für die Signalweiterleitung wurde anhand der lichtaktivierten cAMP Synthese-Aktivität gezeigt. Durch ultraschnelle IR-Spektroskopie wurde die Beteiligung der Seitenketten von Y8 sowie Q50 bestätigt und eine genauere Beschreibung der Wasserstoffbrücken im langlebigen Signalzustand ermöglicht.The light activated kinase Phototropin from Chlamydomonas reinhardtii, the photoactivated adenylylcyclase (PAC) from Euglena gracilis and the BLUF protein Slr1694 from Synechocystis sp. PCC 6803 were investigated concerning the molecular details of the primary photochemistry as well as signal transduction. Phototropin was isolated from Escherichia coli in mg amounts after solubilization with arginine. Without arginine E. coli cAMP receptor protein, which shows high homology to a cAMP activated kinase from C. reinhardtii, was copurified. Full length Phototropin shows similar photochemistry to LOV-domain containing proteins without the kinase including triplet and covalent cysteinyl adduct formation. Signaling state decay is accelerated in the presence of ATP and suggests photoreceptor-kinase interaction. FTIR spectroscopy showed light induced structural changes in the kinase domain. The distance of the photoreceptor domains of 25 Angstrom was determined by ELDOR spectroscopy. Mutation of the side chains of S28, N31 and W91 in Slr1694 showed no conserved influence on the dynamic of the signaling state. Removal of the hydroxyl group of S28 lead to a 15 nm red shift of the absorption spectrum as a result of altered hydrogen bond coordination of the cofactor. Introduction of positively charged side chains at the position of N31 strengthened the binding of phosphorylated flavins. An artificial flavin like roseoflavin was introduced in Slr1694 by coexpression of a bacterial flavin transporter. The essential role of M152 in PAC for signal transduction was shown by determination of light activated cAMP synthesis activity. Ultrafast IR spectroscopy confirmed the contribution of Y8 and Q50 in the photocycle and gave a more detailed description of the hydrogen bonding situation in the signaling state.
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Schäfer, Lars. "Photoactivated processes in condensed phase studied by molecular dynamics simulations /." 2007. http://www.gbv.de/dms/bs/toc/539953806.pdf.
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Chou, Yu-Ching, and 周育晴. "Development of Photoactivated Nitrogen Mustard Anticancer Prodrug Aiming to Selectively Alkylate DNA." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/pnk786.
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碩士國立臺灣大學
化學研究所
106
Development of highly selective anticancer drugs toward tumor cells in order to resolve the severe side effects caused by chemotherapeutic drugs is a primary goal for many research groups. The thesis is aimed to develop a photoactived anticancer prodrug. Incorporation of the aniline mustard, a clinical DNA alkylator, as well as electrophilic pyridinium to the dithienylethene (DTE) core was achieved by multistep synthesis to afford Py-F6DTE-Mus-c and NAEPy-F6DTE-Mus-c. Development of highly selective anticancer drugs toward tumor cells in order to resolve the severe side effects caused by chemotherapeutic drugs is a primary goal for many research groups. The thesis is aimed to develop a photoactived anticancer prodrug. Incorporation of the aniline mustard, a clinical DNA alkylator, as well as electrophilic pyridinium to the dithienylethene (DTE) core was achieved by multistep synthesis to afford Py-F6DTE-Mus-c and NAEPy-F6DTE-Mus-c.
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Li, Shih-Wei, and 李世偉. "Stacked metal-oxide nanomesh type photoactivated gas sensor in room temperature operation." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/66090990108320021895.
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碩士國立臺灣海洋大學
光電科學研究所
102
Abstract In the present thesis, Tungsten oxide (WO3) nanomesh was used as sensing layer and stacked with gold nanomesh as the electrode with polystyrene nanospheres as deposition masks. The stacked metal oxide nanomesh type photoactivated gas sensor was deposited by using thermal evaporation technique. The novel structure decreases the response time and increases the sensing response at room temperature as the surface-to-volume ratio increases. The stacked structure can also reduce the length between the two sensor electrodes and enhance visible light absorption. Hence reducing the electrode distance, the sensing response can be reached the steady state quickly. Fabricating monolayer of self-assembled nanospheres through spin coating is simple and fast process, the size of nanopores can be easily controlled by selecting desired sizes of nanospheres. Keywords: stacked metal-oxide nanomesh, photoactivated gas sensor, nanosphere lithography technique, response time, room temperature operation
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Schäfer, Lars [Verfasser]. "Photoactivated processes in condensed phase studied by molecular dynamics simulations / von Lars Schäfer." 2007. http://d-nb.info/985556978/34.
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Lawrence, R. L., Zak E. Hughes, V. J. Cendan, Y. Liu, C. K. Lim, P. N. Prasad, M. T. Swihart, T. R. Walsh, and M. R. Knecht. "Optical control of nanoparticle catalysis influenced by photoswitch positioning in hybrid peptide capping ligands." 2018. http://hdl.handle.net/10454/16580.
Full textAbstract:
YesHere we present an in-depth analysis of structural factors that modulate peptide-capped nanoparticle catalytic activity via optically driven structural reconfiguration of the biointerface present at the particle surface. Six different sets of peptide-capped Au nanoparticles were prepared, in which an azobenzene photoswitch was incorporated into one of two well-studied peptide sequences with known affinity for Au, each at one of three different positions: The N- or C-terminus, or mid-sequence. Changes in the photoswitch isomerization state induce a reversible structural change in the surface-bound peptide, which modulates the catalytic activity of the material. This control of reactivity is attributed to changes in the amount of accessible metallic surface area available to drive the reaction. This research specifically focuses on the effect of the peptide sequence and photoswitch position in the biomolecule, from which potential target systems for on/off reactivity have been identified. Additionally, trends associated with photoswitch position for a peptide sequence (Pd4) have been identified. Integrating the azobenzene at the N-terminus or central region results in nanocatalysts with greater reactivity in the trans and cis conformations, respectively; however, positioning the photoswitch at the C-terminus gives rise to a unique system that is reactive in the trans conformation and partially deactivated in the cis conformation. These results provide a fundamental basis for new directions in nanoparticle catalyst development to control activity in real time, which could have significant implications in the design of catalysts for multistep reactions using a single catalyst. Additionally, such a fine level of interfacial structural control could prove to be important for applications beyond catalysis, including biosensing, photonics, and energy technologies that are highly dependent on particle surface structures.
Air Office of Scientific Research, grant number FA9550-12- 1-0226.
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Babu, Balaji. "Studies on Photocytotoxic Ferrocenyl Conjugates." Thesis, 2014. http://hdl.handle.net/2005/3028.
Full textAbstract:
The present thesis deals with different aspects of the chemistry and photo-biology of various ferrocene-conjugates, their interaction with double helical DNA, DNA photocleavage and photo-enhanced cytotoxicity in visible light, localization and cellular uptake to study the mechanism of cell death. Phenyl analogues of the active complexes have been synthesized and used for comparison in biological assays.
Chapter I presents an overview of cancer and its types, various treatments for cancer. A general overview on the Photodynamic Therapy, a new modality of light activated cancer treatment and its various possible mechanism of action, has been made. The promise of photoactivated chemotherapy is discussed with recently developed metal based antitumor agents. Biological applications of few ferrocene conjugates as anticancer and anti-malarial agents are discussed. The objective of the present investigation is also presented in this chapter.
Chapter II presents the synthesis, characterization, structure, DNA binding, DNA photocleavage, photocytotoxicity and cellular localization of ferrocene-conjugated dipicolylamine oxovanadium(IV) complexes of curcumin. To explore the role of the ferrocenyl moiety the phenyl analogue of the ferrocenyl complexes is synthesized and used as a control for comparison purpose.
Chapter III deals with the photo-induced DNA cleavage and photo-enhanced cytotoxicity of ferrocene-conjugated oxovanadium(IV) complexes of heterocyclic bases. The synthesis, characterization, structural comparisons, DNA binding, DNA photocleavage and photocytotoxic activity in visible light are discussed in detail.
Chapter IV describes the synthesis, characterization and structure of ferrocene-conjugated oxovanadium(IV) complexes of acetylacetonate derivatives. The complexes are evaluated for DNA binding, DNA photocleavage and photocytotoxic activity in HeLa, MCF-7, 3T3 cells in visible light. The fluorescent nature of the complexes is used to study the cellular localization of the complexes and the mechanism of cell death induced by the complexes is also discussed.
Chapter V presents the photocytotoxic effect of ferrocene-conjugated oxovanadium(IV) complexes of different curcuminoids in HeLa , HepG2 and 3T3 cells. Curcumin based fluorescence has been successfully used to study the cellular uptake and localization behavior of the complexes. The positive role of the ferrocenyl complex is evident from the ~4 fold increase in its photocytotoxicity compared to the phenyl analogue. The apoptotic mode of cell death is evident from nuclear co-staining using Hoechst dye.
Chapter VI describes the synthesis, characterization and photochemotherapeutic efficacy of ferrocene conjugates of N-alkyl pyridinium salts. Mitochondria targeting property of ferrocene compound having n-butyltriphenylphosphonium group has been studied by JC-1 assay. FACS analysis showed significant sub G1/G0 phase cell-cycle arrest in cancer cells on visible light treatment.
Finally, the summary of the dissertation and conclusions drawn from the present investigations are presented.
The references in the text have been indicated as superscript numbers and compiled at the end of each chapter. The complexes presented in this thesis are represented by bold-faced numbers. Crystallographic data of the structurally characterized complexes are given in CIF format in the enclosed CD (Appendix-I). Due acknowledgements have been made wherever the work described is based on the findings of other investigators. Any unintentional omission that might have happened due to oversight or mistake is regretted.
INDEX WORDS: Ferrocene conjugates Crystal structure DNA binding DNA photocleavage Photocytotoxicity Vanadium Cellular Imaging
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Ho, Yu-Hsuan, and 何羽軒. "Integration of photoactivated metal oxide based gas sensor with organic light emitting device: nanoscale fabrication process and light extraction techniques of optoelectronic device applied in sensor platform." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/01092324064979716482.
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博士國立臺灣大學
電子工程學研究所
102
In the dissertation, we developed three novel nanofabrication techniques to fabricate the self-aggregated floccule-like ZnO nanostructures, ZnO nanomesh, and nanogrinded WO3 nanoparticles as the gas sensing layers of the photoactivated gas sensors operated in room temperature. The proposed nanofabrication techniques not only increase the surface-to-volume ratio of the metal-oxide materials, but also improve its light absorption and the activation effects for the gas sensing. In order to integrate the photoactivated gas sensor and the activation light sources, the sensing platform with the transparent ITO interdigitated electrodes were fabricated by using conventional photolithography process. The surface-emitting light source, RGB OLED, was first applied as the activation source to achieve visible light-activated gas sensing. And we designed and fabricated three light extraction techniques applied in OLEDs to greatly improve the luminous efficiency. By applying internal and external light extraction micro-/nanostructures, the efficiency of OLEDS was increased by 100% at some specific angles.
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Amaral, Ana Carolina Palmeira do. "Illuminating G protein-coupled receptors: a bioluminescence-based method to photoactivate receptor ligands." Master's thesis, 2019. http://hdl.handle.net/10316/88003.
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Dissertação de Mestrado em Bioquímica apresentada à Faculdade de Ciências e TecnologiaRecetores acoplados à proteína G são alvos terapêuticos-chave para muitas condições patológicas. Estudos demonstraram que os recetores A2A de adenosina (A2AR) e D2 de dopamina (D2R) acoplados à proteína G formam heterómeros A2AR-D2R no estriado. A estequiometria deste heterómero encontra-se alterada na doença de Parkinson (DP) e a sinalização mediada pelos recetores A2A pode ser promovida. Deste modo, os recetores A2A são o alvo farmacológico de eleição na DP que mais tem recebido atenção nos últimos anos. No entanto, a ubiquidade deste recetor tem dificultado a seletividade no tempo e no espaço de fármacos baseados em adenosina, levando à diminuição do seu efeito terapêutico. A fotofarmacolgia tem vindo a desenvolver novos fármacos, por exemplo, compostos caged nos quais a sua atividade pode ser controlada de uma forma espácio-temporal através do uso de uma fonte de luz. MRS7145 (caged-SCH442416) foi o primeiro antagonista caged dos recetores A2A a ser sintetizado. Quando irradiado (405 nm), através de uma fonte externa de luz, este composto exibiu um perfil de antagonista relativamente aos recetores A2A em células vivas. No modelo de murganho da DP, induzido pela injeção de 6 hidroxidopamina (6-OHDA), demonstrou melhorias dos sintomas motores causados por esta doença. No entanto, a aplicação deste método envolve uma cirurgia ao cérebro complicada e requer o implante de fibras óticas, o que pode limitar a sua utilidade. O objetivo da presente tese foi avaliar se a bioluminescência gerada pela oxidação de coelenterazina 400a, através da enzima nanoluciferase (NL) acoplada ao recetor A2A (A2ARNL), seria suficiente para efetuar a libertação (uncaging) do composto MRS7145 em células vivas. Inicialmente, foi criada uma linha celular estável de células HEK-293 expressando permanentemente A2ARNL. Foram detetados baixos níveis de expressão deste recetor na membrana de células pertencentes à linha celular estável, comparativamente aos níveis detetados em células transientemente transfectadas com o mesmo vetor. Todavia, os valores acumulados de monofosfato cíclico de adenosina (cAMP) e alterações em impedância celular obtidos, após incubação com forskolina (ativador da adenilato ciclase), CGS21680 (agonista) e ZM241385 (antagonista), asseguraram a funcionalidade do recetor na linha celular criada. Além disso, 15 minutos de incubação com coelenterazina 400a, ou com o seu solvente, etanol, não provocou qualquer diminuição na viabilidade celular. No entanto, incubação com coelenterazina 400a levou à diminuição dos níveis de cAMP produzidos pela ação do agonista CGS21680, alterando as condições da ativação do recetor. Coelenterazina 400a não teve qualquer efeito na atividade do composto SCH442416 em bloquear o recetor A2A. Por fim, foi avaliado o bloqueio autónomo do recetor A2A mediado pela libertação (uncaging) do composto MRS7145 dependente da bioluminescência gerada pela enzima nanoluciferase acoplada. Quando incubado com coelenterazina 400a, o composto MRS7145 impediu a ativação do recetor de A2A mediada pelo agonista CGS21680. Resumindo, o método descrito baseado em bioluminescência, demonstrou a primeira evidência do uncaging do composto MRS7145 e subsequente libertação do composto SCH442416 em células vivas, sob um controlo espácio-temporal e independente de uma fonte externa de luz. Este método apresenta grande potencial para ser futuramente otimizado e aplicado no tratamento de distúrbios motores, incluindo a doença de Parkinson e, ainda, em terapias que visem a utilização de fármacos cuja atividade possa ser controlada por uma fonte de luz.
G protein-coupled receptors are key therapeutic targets for many pathological conditions. Studies support that the G protein-coupled adenosine A2A receptor (A2AR) and dopamine D2 receptor (D2R) form A2AR‐D2R heteromers in the striatum. The stoichiometry of this receptor heteromer is altered in Parkinson’s disease (PD) and A2AR signaling may be promoted. Hence, the A2AR represents the latest pharmacological target in PD. However, owing to the ubiquity of this receptor, it has been difficult to achieve drug selectivity in time and space for adenosine-based drugs which diminishes their therapeutic use. Photopharmacology has been developing novel drugs, e.g., caged-compounds, whose activity can be controlled in a spatiotemporal-manner with the use of a light source. MRS7145 (caged-SCH442416) was the first A2AR photo-caged antagonist to be synthesized whose external irradiation (405 nm) showed a light-dependent A2AR antagonist activity in living cells and antiparkinsonian effects in a hemiparkinsonian 6-hyroxydopamine (6-OHDA)-lesioned mouse model. However, this approach involves laborious brain surgery and optic fiber implants that may limit its utility. The aim of the present thesis was to evaluate whether the bioluminescence produced by an A2AR-coupled nanoluciferase (NL)-mediated coelenterazine 400a oxidation would be able to uncage MRS7145 in living cells. To begin with, a HEK-293 stable cell line expressing a previously engineered A2ARNL was created. Low receptor expression levels were found at the membrane of cells belonging to the stable cell line when compared to transiently transfected cells with the same construct. However, the cAMP accumulated levels and changes in cellular impedance obtained upon cell incubation with forskolin (adenylyl cyclase stimulator), CGS21680 (agonist), and ZM241385 (antagonist), ensured receptor functionality. Moreover, 15 minutes incubation with coelenterazine 400a or its solvent, ethanol, had no effect in decreasing cell viability, while incubation with coelenterazine 400a decreased CGS21680-induced cAMP accumulation altering receptor activation in the generated stable cell line. Coelenterazine 400a incubation did not affect SCH442416-induced receptor blockade. Finally, the autaptic A2AR blockade mediated by receptor’s bioluminescence-dependent uncaging of MRS7145 was evaluated. MRS7145 precluded CGS21680-induced receptor activation when incubated with coelenterazine 400a in living cells. Altogether, the described bioluminescence-based method provided the first proof of concept in uncaging MRS7145 and subsequent photorelease of SCH442416 in living cells, under a spatiotemporal control and independently of an external light source. This method demonstrates potential to be further optimized to be applied in the management of movement disorders, including Parkinson’s disease, and other prospective smart therapies which aim to utilize photocontrolled drugs.
Outro - SAF2017‐87349‐R from Ministerio de Economía y Competitividad‐Spanish Government, I+D (Project title: “Lighthing up dopamine, adenosine and GPR37 receptors in neurological and neuropsychiatric diseases”).
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Sousa, Pedro Miguel Gonçalves de. "Contração de polimerização de resinas compostas fotoativadas – revisão conceptual e procedimentos para a sua redução." Master's thesis, 2019. http://hdl.handle.net/10284/8540.
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As resinas compostas fotoativadas sofrem uma contração volumétrica que resulta na sua passagem do estado viscoso para um estado sólido, contração essa que gera tensão entre as paredes cavitárias e o material restaurador. Para minimizar a ocorrência desta situação, e visando um maior sucesso clínico, existem alguns procedimentos que devem ser do conhecimento do Médico Dentista.
Pretende-se, com esta dissertação, explorar a temática da contração de polimerização das resinas compostas, atualizando o conceito, bem como enumerar os fatores e consequências associados e, ainda, abordar os procedimentos clínicos que visam a sua redução. Para isso, foi realizada uma revisão de literatura nas bases de dados PubMed/Medline, B-On e Scielo.
Apesar da abundância de estudos recentes disponíveis, destaca-se a necessidade da realização de novas pesquisas que visem uma maior elucidação sobre o tema, nomeadamente, em relação à associação dos diversos fatores envolvidos e, ainda, no desenvolvimento de novos materiais restauradores.Photoactivated composite resins, while undergoing a change in physical state from viscous to solid, go through a volumetric contraction, which additionally generates stress between cavity walls and the restoring material. In order to minimize this phenomenon and for the purpose of achieving the best clinical outcome, there are some procedures that should be well known by the dental professionals. This dissertation aims to understand composite resins’ polymerization shrinkage, providing a concept update and exploring the several factors and consequences related to it, as well as the clinical procedures that enable its reduction. A literature review was performed on the PubMed/Medline, B-On and Scielo databases. Despite the abundance of available recent studies, it proves necessary to carry out further research aimed at elucidating the subject, namely in regard to the association of the various factors involved and, also, in the development of new restorative materials.
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Goswami, Tridib Kumar. "Studies On The Photocytotoxic Effect Of Ferrocene-Conjugated Copper(II) Complexes." Thesis, 2012. http://etd.iisc.ernet.in/handle/2005/2528.
Full textAbstract:
The present thesis deals with different aspects of the chemistry and photo-biology of various ferrocene-conjugated metal complexes, their interaction with double helical DNA, DNA photocleavage and photo-enhanced cytotoxicity in visible light. Phenyl analogues of the active complexes have been synthesized and used for comparison in biological assays.
Chapter I provides an introduction to the potential of metal complexes as photochemotherapeutic agents with special reference to organometallic compounds. A brief overview of Photodynamic Therapy (PDT) as a new modality of cancer treatment has been given. Various modes of non-covalent interactions of small molecules with duplex DNA are mentioned. Recent reports on the metal-based photocytotoxic and DNA cleaving agents including photoactivatable organometallic compounds are discussed. The objective of the present investigation is also presented in this chapter.
Chapter II presents the synthesis, characterization, structure, DNA binding, DNA photocleavage, photocytotoxicity, mechanism of cell death and cellular localization of ferrocene-conjugated L-methionine reduced Schiff base Cu(II) complexes of phenanthroline bases. To explore the role of the ferrocenyl moiety the phenyl analogues of the ferrocenyl complexes are synthesized and used as controls for comparison purpose.
Chapter III deals with the photo-induced DNA cleavage and photo-enhanced cytotoxicity of ferrocene-appended L-tryptophan Cu(II) complexes of heterocyclic bases. The synthesis, characterization, structural comparisons, DNA binding, DNA photocleavage, photocytotoxic activity and cell death mechanism in visible light are discussed in detail.
Chapter IV describes the synthesis, characterization and structure of ferrocenylmethyl-L-tyrosine Cu(II) complexes of phenanthroline bases. The complexes are evaluated for DNA binding, DNA photocleavage and photocytotoxic activity in visible light. The cellular localization of the complexes and the mechanism of cell death induced by the complexes are also discussed.
Chapter V presents the photocytotoxic effect of ferrocene-conjugated L-amino acid reduced Schiff base Cu(II) complexes of anthracenyl/pyrenyl imidazophenanthroline. The ability of the complexes to bind to double helical DNA and cleave it under photo-illumination conditions is described. Evaluation of the complexes as photochemotherapeutic agents and comparison with currently clinically available drug Photofrin are presented. The mechanism of cancer cell death and cellular localization of the complexes are studied by fluorescence microscopy.
Chapter VI describes the synthesis, characterization and photochemotherapeutic efficacy of Cu(II) complexes having ferrocene-appended L-amino acid reduced Schiff base ligands and the naturally occurring polyphenol curcumin. Stabilization of curcumin by complexation to metal for improved photodynamic effect in cancer cells is described with comparison to the parent dye and clinically used drug Photofrin. The mechanism of cell death induced by the copper complexes and their localization in cancer cells are also presented.
Finally, the summary of the dissertation and conclusions drawn from the present investigations are presented.
The references in the text have been indicated as superscript numbers and compiled at the end of each chapter. The complexes presented in this thesis are represented by bold-faced numbers. Crystallographic data of the structurally characterized complexes are given in CIF format in the enclosed CD (Appendix-I). Due acknowledgements have been made wherever the work described is based on the findings of other investigators. Any unintentional omission that might have happened due to oversight or mistake is regretted.