Capillary electrophoresis is a widely used separation method of analytical chemistry. Addition of a selector into the background electrolyte extends its applicability to separation of enantiomers or of compounds of similar physicochemical properties. In analytical practice, mixtures of selectors are also commonly used - either prepared intentionally to achieve better separation or because commercially available selectors may be mixtures of compounds differing in the degree of substitution and substituent positions. Mathematical description of these systems, which are highly relevant in analytical practice, can simplify search for optimal separation conditions. Also, it provides a useful insight into the separation mechanism. In this work, a model of electromigration of an analyte interacting with a mixture of two selectors is proposed and experimentally verified. This model results from a more general description of systems with an arbitrary number of selectors. The model shows that a selector mixture can be treated as a single selector if the ratio of the respective selector concentrations is kept constant. When the mixture is prepared intentionally, this description predicts, how separation potential of the mixture changes with its composition. Thus it allows the optimal composition and total...

Theoretical studies of the molecular mechanisms responsible for the formation and stability of protein complexes have gained importance due to their practical applications in the understanding of the molecular basis of several diseases, in protein engineering and biotechnology. The objective of this project is to critically analyze and refine a coarse-grained force field for protein-protein interactions based on experimental thermodynamic properties and to apply it to cancer-related S100A4 protein system. Our ultimate goal is to generate knowledge for a better understanding of the physical mechanisms responsible for the association of particular proteins in different environments. We studied the role of short and long-range interactions on the complexation of homo-associations. Furthermore, we analyzed the influence of the pH and its correlation with the charge regulation mechanism. We analyzed and refined the adjustable Lennard-Jones parameter for a mesoscopic model based on experimental second virial data for lysozyme, chymotrypsinogen, and ribonuclease A via Monte Carlo simulations. From of that, the S100A3 protein was used to test the new calibrated parameters. Finally, we evaluated the dimerization process of S100A4 proteins, observing the role of physical-chemistry variables involved in the thermodynamical stability of different oligomers. / Estudos teóricos dos mecanismos moleculares responsáveis pela formação e estabilidade dos complexos de proteínas vêm ganhando importância devido às suas aplicações práticas no entendimento da base molecular de várias doenças, em engenharia de proteínas e biotecnologia. O objetivo deste projeto é analisar criticamente e aperfeiçoar um campo de força de granulidade grossa para interação proteína-proteína com base em propriedades termodinâmicas experimentais e aplicá-lo ao sistema proteico S100A4 relacionado com o câncer. Nosso objetivo final é gerar conhecimento para uma melhor compreensão dos mecanismos físicos responsáveis pelas associações de proteínas particulares em diferentes ambientes. Estudamos o papel das interações de curto e longo alcance na complexação de homo-associações. Além disso, analisamos a influência do pH e sua correlação com o mecanismo de regulação de cargas. Por meio de simulações Monte Carlo, analisamos e refinamos o parametro ajustável de Lennard-Jones para um modelo mesoscópico, usando dados experimentais do segundo virial para a lisozima, o quimotripsinogênio e a ribonuclease A. A partir disso, a proteína S100A3 foi usada para testar os novos parâmetros calibrados. Finalmente, foi avaliado o processo de dimerização das proteínas S100A4, observando o papel de algumas variáveis físico-químicas envolvidas na estabilidade termondinâmica de diferentes oligómeros.

<p>The object of this work is to obtain a fundamentalunderstanding of the principal issues concerning the handlingof an aqueous WC-Co powder suspension.</p><p>The WO3 surface layer on the oxidised tungsten carbidepowder dissolves at pH>3 with the tungsten concentrationincreasing linearly with time. Adding cobalt powder to thetungsten carbide suspension resulted in a significant reductionof the dissolution rate at pH<10. Electrokinetic studiesindicated that the reduced dissolution rate may be related tothe formation of surface complexes; the experiments showed thatCo species in solution adsorb on the oxidised tungsten carbidepowder.</p><p>The surface forces of oxidised tungsten and cobalt surfaceswere investigated using the atomic force microscope (AFM)colloidal probe technique. The interactions at various ionicstrengths and pH values are well described by DLVO theory. Theadsorption of cobalt ions to tungsten oxide surfaces resultedin an additional non-DLVO force and a reduced absolute value ofthe surface potential. It was shown that the adsorption ofpoly(ethylene imine) (PEI) to the WO3 surfaces induces anelectrosteric repulsion.</p><p>The properties of spray-dried WC-Co granules were related tothe WC primary particle size, and the poly(ethylene glycol)(PEG) binder and PEI dispersant content in aqueous WC-Cosuspensions. The granule characterisation includes a new methodfor measuring the density of single granules. The increase inthe fracture strength of granules produced from suspensionsthat were stabilised with PEI was related to a more densepacking of the WC-Co particles.</p><p>The AFM was used to study the friction and adhesion ofsingle spray-dried WC-Co granules containing various amounts ofPEG binder. The adhesion and friction force between two singlegranules (intergranular friction) and between a granule and ahard metal substrate (die-wall friction) have been determinedas a function of relative humidity. The granule-wall frictionincreases with binder content and relative humidity, whereasthe granule-granule friction is essentially independent of therelative humidity and substantially lower than the granule-wallfriction at all PEG contents.</p><p><b>Key words:</b>Hard Metal, Cemented Carbide, WC-Co, TungstenCarbide, Cobalt, Oxidation, Dissolution, Surface Complexation,XPS, AFM, Colloidal Probe, Hamaker Constant, Cauchy, WO3,CoOOH, ESCA, Zeta-Potential, Surface Potential, Poly(ethyleneimine), PEI, Suspension, van der Waals, Steric, Spray-Dried,Poly(ethylene glycol), Strength, Density, Friction, Adhesion,Granule, PEG, Pressing, FFM.</p>

Cette thèse a permis de mieux comprendre les mécanismes de complexation des terres rares par les acides humiques afin d'expliquer la variabilité des spectres de terres rares observée dans les eaux riches en matière organique. Cette étude montre que l'hétérogénéité des groupements fonctionnels complexants des acides humiques peut induire différents types de spectres de complexation des terres rares en fonction des conditions physico-chimiques. En effet, à pH acide, lorsque le rapport terres rares/acides humiques augmente, les terres rares se lient majoritairement à des sites carboxyliques multidentates puis monodentates qui ont, respectivement, une plus forte affinité pour les terres rares lourdes et intermédiaires. Lorsque le pH augmente, la participation de sites phénoliques devient plus importante pour les terres rares lourdes tandis que les légères restent liées à des sites carboxyliques. Des expériences de compétition entre les terres rares et le fer ou l'aluminium pour la complexation par les acides humiques ont également été réalisées. A pH neutre, Al est un plus fort compétiteur pour les terres rares légères, et se lie donc préférentiellement à des sites carboxyliques, tandis que Fe est un compétiteur pour toutes les terres rares, et se lie donc aussi bien aux sites carboxyliques que phénoliques. Ainsi, le rapport cation dissous/acides humiques, le pH et la natures des cations compétiteurs peuvent expliquer la variabilité des spectres de terres rares observée dans les eaux naturelles. De plus, les terres rares peuvent être utilisées comme sonde des mécanismes de complexation des cations par les acides humiques, comme ici pour Al et Fe.

Dans une première partie, nous mesurons l'affinité de l'interaction entre [Ru(pby)2dppz]2+ et l'ADN en utilisant la luminescence induite lors de la complexation. Nous étudions l'évolution de l'affinité lorsque la force ionique de la solution augmente. Dans une deuxième partie, nous modifions les extrémités d'un double brin d'ADN en y greffant des fluorophores. De la mesure de transfert d'énergie non-radiative entre ces fluorophores, nous étudions l'évolution de la longueur du complexe. Nous effectuons un dosage d'un double brin de 15 paires de bases d'ADN par le complexe ruthéné. Nous nous servons de la luminescence induite par l'intercalation du groupement dppz. Cependant, l'incrément de luminescence par groupement intercalé n'est pas connu, et nous ne pouvons pas le mesurer en saturant le brin d'ADN. Nous utilisons alors une technique mise au point par Nishida [Method for Measuring the Binding of Small Molecules to Proteins from Binding-Induced Alterations of Physical-Chemical Properties], dans laquelle deux titrations de deux solutions d'ADN de deux concentrations différentes sont effectuées. En utilisant le fait que, lorsque deux solutions d'ADN complexé par le composé ruthéné, possèdent la même luminescence par paire de base , le taux de complexation de ces deux solutions doit être le même, nous pouvons alors déterminer, sans hypothèse supplémentaire, le taux de complexation de l'ADN. De l'évolution de ce taux en fonction avec la concentration de ligand, nous déduisons son affinité pour l'ADN. Nous étudions maintenant le changement de longueur d'un double brin d'ADN de 15 paires de bases, modifié à ses deux extrémités par deux fluorophores : Alexa488 et Alexa568. Lorsque Alexa 488 est porté dans un état excité, il peut se désexciter en transférant de l'énergie de manière non-radiative à Alexa568, qui se désexcite alors en émettant des photons de plus faibles énergie que ceux émis par Alexa488. L'efficacité de ce transfert d'énergie peut être quantifié à partir de la mesure des intensités émises à basse et haute énergie. Elle dépend a priori de l'efficacité couplage (et en conséquence de la distance) entre les deux fluorophores. Nous effectuons des mesures de temps de vie des états excités de chacun des fluorophores. Nous avons observé que l'addition de ligand a pour conséquence une forte inhibition quenching des fluorophores. De l'analyse de l'évolution du temps de vie du fluorophore donneur d'une part et de celui du fluorophore accepteur d'autre part, nous déduisons l'évolution de l'efficacité du transfert d'énergie en fonction de la concentration de ligand. Nous confrontons les résultats obtenus par chacune de ces analyses, et en déduisons finalement, en nous servant de l'analyse de l'équilibre effectuée dans la première partie, l'évolution de la longueur de la chaîne en fonction du taux de complexation

Die Charakterisierung von verzweigten Polymeren stellt eine große Herausforderung dar. In dieser Arbeit wurden zum einen die Asymmetrische Fluss-Feldflussfraktionierung (AF4) als Alternative zur Größenausschlusschromatographie angewandt, um dendritische Polymere zu charakterisieren. Dabei wurden erstmals auch Komplexierungs-und Aggregationsstudien von dendritischen Glykopolymeren durchgeführt. Weiterhin ist es mittels Adaption der Phasenverteilungschromatographie gelungen, in Abhängigkeit des Verzweigungscharakters aufzutrennen. Hierbei konnten lineare und sternförmige Polystyrenproben separiert werden.

Dreiwertige Actinide (An(III)) und Lanthanide (Ln(III)) stellen im Falle ihrer Inkorporation eine ernste Gefahr für die Gesundheit des Menschen dar. An(III) sind künstlich erzeugte, stark radioaktive Elemente, die insbesondere bei der nuklearen Energiegewinnung in Kernkraftwerken entstehen. Durch Störfälle oder nicht fachgerechte Lagerung radioaktiven Abfalls können sie in die Umwelt und die Nahrungskette des Menschen gelangen. Ln(III) sind hingegen nicht radioaktive Elemente, die natürlicherweise vorkommen und für vielfältige Anwendungen in Technik und Medizin abgebaut werden. Folglich kann der Mensch sowohl mit An(III) als auch Ln(III) in Kontakt kommen bzw. sie inkorporieren. Es ist daher von enormer Wichtigkeit, das Verhalten dieser Elemente im menschlichen Körper aufzuklären. Während makroskopische Vorgänge wie Verteilung, Anreicherung und Ausscheidung bereits sehr gut untersucht sind, ist das Wissen hinsichtlich der chemischen Bindungsform (Speziation) von An(III) und Ln(III) in Körperflüssigkeiten noch sehr lückenhaft. In der vorliegenden Arbeit wurde daher erstmals die chemische Bindungsform von Cm(III) und Eu(III) in natürlichem menschlichem Urin (in vitro) spektroskopisch aufgeklärt und die gebildeten Komplexe identifiziert. Hierzu wurden auch grundlegende Untersuchungen zur Komplexierung von Cm(III) und Eu(III) in synthetischem Modellurin sowie mit den urinrelevanten organischen Modellliganden Harnstoff, Alanin, Phenylalanin, Threonin und Citrat durchgeführt und die noch unbekannten Komplexbildungskonstanten bestimmt. Abschließend wurden alle experimentellen Ergebnisse mit Literaturdaten und Vorherberechnungen mittels thermodynamischer Modellierung verglichen. Auf Grund der hervorragenden Lumineszenzeigenschaften von Cm(III) und Eu(III) konnte insbesondere auch die Eignung der zeitaufgelösten laserinduzierten Fluoreszenzspektroskopie (TRLFS) als Methode zur Untersuchung dieser Metallionen in unbehandelten, komplexen biologischen Flüssigkeiten demonstriert werden. Die Ergebnisse dieser Arbeit liefern damit neue Erkenntnisse zu den biochemischen Reaktionen von An(III) und Ln(III) in Körperflüssigkeiten auf molekularer Ebene und tragen zu einem besseren Verständnis der bekannten, makroskopischen Effekte dieser Elemente bei. Darüber hinaus sind sie die Grundlage weiterführender in-vivo-Untersuchungen. / In case of incorporation, trivalent actinides (An(III)) and lanthanides (Ln(III)) pose a serious health risk to humans. An(III) are artificial, highly radioactive elements which are mainly produced during the nuclear fuel cycle in nuclear power plants. Via hazardous accidents or nonprofessional storage of radioactive waste, they can be released in the environment and enter the human food chain. In contrast, Ln(III) are nonradioactive, naturally occurring elements with multiple applications in technique and medicine. Consequently it is possible that humans get in contact and incorporate both, An(III) and Ln(III). Therefore, it is of particular importance to elucidate the behaviour of these elements in the human body. While macroscopic processes such as distribution, accumulation and excretion are studied quite well, knowledge about the chemical binding form (speciation) of An(III) and Ln(III) in various body fluids is still sparse. In the present work, for the first time, the speciation of Cm(III) and Eu(III) in natural human urine (in vitro) has been investigated spectroscopically and the formed complex identified. For this purpose, also basic investigations on the complex formation of Cm(III) and Eu(III) in synthetic model urine as well as with the urinary relevant, organic model ligands urea, alanine, phenylalanine, threonine and citrate have been performed and the previously unknown complex stability constants determined. Finally, all experimental results were compared to literature data and predictions calculated by thermodynamic modelling. Since both, Cm(III) and Eu(III), exhibit unique luminescence properties, particularly the suitability of time-resolved laser-induced fluorescence spectroscopy (TRLFS) could be demonstrated as a method to investigate these metal ions in untreated, complex biofluids. The results of this work provide new scientific findings on the biochemical reactions of An(III) and Ln(III) in human body fluids on a molecular scale and contribute to a better understanding of the known macroscopic effects of these elements. Furthermore, they are the basis of subsequent in vivo investigations.

Made available in DSpace on 2014-12-17T14:07:19Z (GMT). No. of bitstreams: 1 WilsonJO_TESE.pdf: 5377189 bytes, checksum: 886cb0d3eb97075a3db2f3b7c1a15af0 (MD5) Previous issue date: 2013-10-21 / Fuel cells are considered one of the most promising ways of converting electrical energy due to its high yield and by using hydrogen (as fuel) which is considered one of the most important source of clean energy for the future. Rare earths doped ceria has been widely investigated as an alternative material for the electrolyte of solid oxide fuel cells (SOFCs) due to its high ionic conductivity at low operating temperatures compared with the traditional electrolytes based on stabilized zirconia. This work investigates the effect of gallium oxide (Gallia) as a sintering aid in Eu doped ceria ceramic electrolytes since this effect has already been investigated for Gd, Sm and Y doped ceria electrolytes. The desired goal with the use of a sintering aid is to reduce the sintering temperature aiming to produce dense ceramics. In this study we investigated the effects on densification, microstructure and ionic conduction caused by different molar fraction of the dopants europium (10, 15 and 20%) and gallium oxide (0.3, 0.6 and 0.9%) in samples sintered at 1300, 1350 and 1450 0 C. Samaria (10 and 20%) doped ceria samples sintered between 1350 and 1450 ?C were used as reference. Samples were synthesized using the cation complexation method. The ceramics powders were characterized by XRF, XRD and SEM, while the sintered samples were investigated by its relative density, SEM and impedance spectroscopy. It was showed that gallia contents up to 0.6% act as excellent sintering aids in Eu doped ceria. Above this aid content, gallia addition does not promote significant increase in density of the ceramics. In Ga free samples the larger densification were accomplished with Eu 15% molar, effect expressed in the microstructure with higher grain growth although reduced and surrounded by many open pores. Relative densities greater than 95 % were obtained by sintering between 1300 and 1350 ?C against the usual range 1500 - 1600 0 C. Samples containing 10% of Sm and 0.9% of Ga reached 96% of theoretical density by sintering at 1350 0 C for 3h, a gain compared to 97% achieved with 20% of Sm and 1% of Ga co-doped cerias sintered at 1450 0 C for 24 h as described in the literature. It is found that the addition of gallia in the Eu doped ceria has a positive effect on the grain conductivity and a negative one in the grain boundary conductivity resulting in a small decrease in the total conductivity which will not compromise its application as sintering aids in ceria based electrolytes. Typical total conductivity values at 600 and 700 ?C, around 10 and 30 mS.cm -1 respectively were reached in this study. Samples with 15% of Eu and 0.9 % of Ga sintered at 1300 and 1350 ?C showed relative densities greater than 96% and total conductivity (measured at 700 ?C) between 20 and 33 mS.cm -1 . The simultaneous sintering of the electrolyte with the anode is one of the goals of research in materials for SOFCs. The results obtained in this study suggest that dense Eu and Ga co-doped ceria electrolytes with good ionic conductivity can be sintered simultaneously with the anode at temperatures below 1350 ?C, the usual temperature for firing porous anode materials / As c?lulas a combust?vel s?o tidas como uma das mais promissoras formas de convers?o de energia el?trica devido ao seu alto rendimento e por utilizar o hidrog?nio como combust?vel, considerado por muitos a principal fonte limpa de energia para o futuro. C?ria dopada com terras raras tem sido amplamente investiga como material alternativo para eletr?lito de c?lulas a combust?vel de ?xido s?lido (SOFC) devido sua alta condutividade i?nica em baixas temperaturas de opera??o quando comparado com os tradicionais eletr?litos ? base de zirc?nia estabilizada. Neste seguimento de pesquisa, este trabalho investiga o efeito do ?xido de g?lio (G?lia) como aditivo de sinteriza??o em eletr?litos cer?micos a base de c?ria dopada com eur?pio, uma vez que este efeito j? foi investigado por outros em eletr?litos ? base de c?ria dopada com Gd, Sm e Y. A meta almejada com a utiliza??o do aditivo de sinteriza??o ? reduzir a temperatura de sinteriza??o para a produ??o de cer?micas densas. Neste trabalho investigou-se o efeito na densifica??o, na microestrutura e na condu??o i?nica causado por diferentes fra??es molares do dopante eur?pio (10, 15 e 20%) e do aditivo de sinteriza??o ?xido de g?lio (0,3; 0,6 e 0,9%), em amostras sinterizadas a 1300, 1350 e 1450 0 C. A c?ria co-dopada com 10 e 20% de Sm e com os mesmos teores do aditivo de sinteriza??o g?lia, sinterizadas a 1350, 1450 e 1500 0 C, tamb?m foi investigada, por sua vez, como par?metro de refer?ncia experimental, haja visto que, nesta pesquisa, adotou-se s?nteses pelo m?todo de complexa??o de c?tions enquanto que os trabalhos encontrados na literatura utilizaram o m?todo convencional. Os p?s cer?micos sintetizados foram caracterizados por FRX, DRX e MEV e as amostras cer?micas sinterizadas por sua densidade relativa, MEV e espectroscopia de imped?ncia. Verifica-se que a G?lia com teores at? 0,6% atua como um excelente aditivo de sinteriza??o na c?ria dopada com Eu. Acima deste teor e at? 0,9% a adi??o da g?lia n?o promove significativos aumentos na densidade da cer?mica. Nas amostras livres do Ga, as maiores densifica??es foram alcan?adas com 15% de Eu, efeito manifestado na micro-estrutura com os maiores crescimentos de gr?os, embora ainda reduzidos e circundados por muitos poros abertos. Densidades relativas superiores a 95% da densidade te?rica podem ser obtidas com sinteriza??es entre 1300 e 1350 0 C, contra as usuais 1500 a 1600 0 C. Com a c?ria co-dopada com 10% de Sm e 0,9% de Ga alcan?ou-se neste trabalho 96% da densidade te?rica com sinteriza??o a 1350 0 C por 3h, um ganho em rela??o aos 97% alcan?ados com a c?ria co-dopada com 20% de Sm e 1% de Ga sinterizada a 1450 0 C por 24h conforme encontrado na literatura. Verifica-se que a adi??o da G?lia em eletr?litos ? base de c?ria dopada com Eu apresenta efeito positivo na condutividade do gr?o e negativo na do contorno de gr?o resultando em uma pequena redu??o na condutividade total, a qual n?o compromete sua promissora aplica??o como aditivo de sinteriza??o. Valores t?picos da condutividade total a 600 e 700 0 C, em torno de 10 e 30 mS.cm -1 respectivamente, foram alcan?ados neste trabalho. As amostras de eletr?litos ? base de c?ria co-dopada com 15% de Eu e 0,9% de Ga, sinterizados a 1300 e 1350 0 C, alcan?aram densidades relativas superiores a 96% e condutividade a 700 0 C entre 20 e 33 mS.cm -1 . A sinteriza??o simult?nea do eletr?lito com o anodo ? uma das metas da pesquisa em materiais para SOFCs. Os resultados alcan?ados neste trabalho sugerem que eletr?litos densos ? base de c?ria co-dopada com Eu e Ga podem ser sinterizados simultaneamente com o anodo ? temperatura de sinteriza??o entre 1300 e 1350 0 C, a faixa de temperatura usual de sinteriza??o do anodo poroso

Ce travail de thèse a consisté à synthétiser de nouveaux chélateurs pour la complexation des ions métalliques d10 toxiques en milieu biologique, comme le cuivre (I), lorsqu'il est présent en excès dans les cellules, et le mercure (II), délétère à l'état de traces. En particulier, des tripodes à trois soufres, inspirés de tripodes fonctionnalisés par trois dérivés cystéine, développés antérieurement au laboratoire, ont été élaborés et leur propriétés de complexation avec le cuivre (I) ont été examinées. Comme les tripodes cystéines, les nouveaux tripodes fonctionnalisés par d'autres dérivés soufrés, en particulier des dérivés de D-Pénicillamine (D-PEN), sont capables de complexer le cuivre (I) dans des environnements CuS3 avec de fortes affinités et sélectivités par rapport au zinc (II) présent dans les milieux biologiques. Des études structurales approfondies effectuées par spectroscopie d'absorption des rayons X (XAS) ont permis de caractériser complètement les complexes et clusters de cuivre (I) formés, de corréler les mesures d'affinités effectuées en utilisant différentes techniques et de rationaliser les relations structure/ affinité observées. L'un des nouveaux tripodes a ensuite été fonctionnalisé pour être ciblé vers les cellules du foie, où une accumulation de cuivre est observée chez les patients atteints de la maladie de Wilson. Les premiers tests biologiques réalisés sur des cellules hépatiques ont montré que l'architecture fonctionnalisée ainsi conçue (CHEL4) est capable de complexer le cuivre (I) en excès in cellulo. Cette étude conforte les résultats obtenus antérieurement au laboratoire avec le tripode cystéine fonctionnalisé (CHEL2) et valide donc le système de vectorisation vers les hépatocytes. Les propriétés de complexation des nouveaux tripodes avec l'ion toxique mercure (II), plus gros et plus mou que l'ion cuivre (I), ont aussi été étudiées. Il a ainsi été établi que les nouveaux tripodes thiolates peuvent aussi stabiliser un environnement trigonal autour du mercure (II). Notre étude a donc montré comment des tripodes soufrés de faible poids moléculaire, judicieusement fonctionnalisés, peuvent accommoder des environnements trigonaux très stables autour des ions mous cuivre (I) et mercure (II). De tels environnements miment plus ou moins les sites trigonaux du cuivre (I) et du mercure (II) trouvés dans les protéines à cuivre (I) (Ctr1, Mac1, Ace 1, COX…), les protéines bactériennes de détoxification du mercure (II) (Mer-R), et les métallothionéines (MTs), petites protéines riches en cystéines qui complexent les ions métalliques en excès ou toxiques dans les cellules. Ces analogies avec les complexes métalliques biologiques permettent de rationnaliser les fortes affinités des nouveaux tripodes pour les ions mous cuivre (I) et mercure (II). Plus généralement, notre étude apporte des règles de design moléculaires pour concevoir des architectures efficaces dédiées à la détoxification des métaux mous en milieu biologiques. Mots clés : cuivre (I), zinc (II), mercure (II), maladie de Wilson, foie, surcharges métalliques, toxicité, chélateurs, tripodes soufrés, cystéine, D-pénicillamine (D-PEN), environnements trigonaux, protéines du cuivre (I), métallothionéines (MTs), Mer-R, Spectroscopie d'Absorption des rayons X (XAS). / This work consisted in the syntheses of new chelators for the binding of soft d10 metal ions in biological media, such as the copper (I) ion, toxic at high levels in the cells, and the mercury (II) ion, deleterious even at low concentrations. In particular, new suphur-based tripodal architectures, derived from the cysteine-based architectures previously designed at the laboratory, have been synthetized and their binding properties with the copper (I) ion have been looked into. As the cysteine-based scaffolds, the new chelators, based on new sulphur compounds, in particular D-Penicillamine (D-PEN) derivatives, complex the copper (I) ion in trigonal CuS3 environments with high affinities and high selectivities with respect to the bioavailable zinc (II) ion. In depth structural studies have been performed by X-Ray Absorption Spectroscopy (XAS) to fully characterize the copper (I) complexes and the copper (I) clusters formed in solution, to correlate the affinity measurements performed using different analytical techniques and to rationalize structure/ affinity relationships. One of the new chelators has been functionalized to be targeted to the liver cells, where copper (I) overloads are observed when people suffer from the Wilson's disease. The first biological experiments carried out in hepatocytes, have shown that the functionalized chelator (CHEL4) complexes excess copper (I) in cellulo. This study supports the results previously obtained with the functionalized cysteine-based architecture (CHEL2) and thus validates the targeting system. The binding properties of the new tripodal architectures with the mercury (II) ion, bulkier and softer than the copper (I) ion, have also been studied. It has been established that the new chelators also stabilize trigonal environments around the mercury (II) ion. Thus this study has shown how low molecular weight sulphur-based tripodal architectures, judiciously functionalized, are able to adapt stable sulphur-only trigonal environments around the soft metal ions, copper (I) and mercury (II). Such environments reproduce more or less the trigonal binding sites found in copper (I) proteins (Crt1, Mac1, Ace1, COX…), bacteria proteins dedicated to mercury (II) detoxification (Mer-R) and metallothioneins (MTs), which are small cysteine-rich proteins in charge of the detoxification of toxic metal ions in cells. Those structural analogies shared with the biological metallic complexes allow us to rationalize the high affinities of the new tripodal architectures for soft metal ions. In a more extended point of view, this study brings some guidelines of molecular design to elaborate efficient chelators dedicated to the detoxification of soft metal ion in biological media. Keywords: copper (I), zinc (II), mercury (II), Wilson's disease, liver, metal overloads, toxicity, chelators, sulphur-based tripods, cysteine, D-penicillamine (D-PEN), trigonal environments, copper (I) proteins, metallothioneins, Mer-R, X-Ray Absorption Spectroscopy (XAS).

Made available in DSpace on 2016-06-02T19:29:50Z (GMT). No. of bitstreams: 1 TeseSPG.pdf: 896184 bytes, checksum: 0237c1553b20f09b9264cf38e782d113 (MD5) Previous issue date: 2004-06-30 / The influence of phytoplankton and their excreted materials in natural waters have been considered important issues among metal speciation studies. This work focused on the potential influence of the high molecular weight materials excreted by dominant phytoplankton species of Barra Bonita reservoir (Anabaena spiroides, Microcystis aeruginosa and Aulacoseira granulata) in the speciation and complexation of Cu and Cd. Therefore, this study comprised field and laboratory studies. Seasonal samplings were made during a period of two years in the reservoir. The total, ionic and organic concentrations of Cu and Cd were determined, as well as the complexation parameters with ligands present in the reservoir water. Also, the dissolved organic carbon and physico-chemical parameters of the water column were obtained. A speciation model was applied to metal complexation parameters and total metal concentrations obtained in field investigations. Laboratory cultures of the selected microalgae were made to obtain high molecular weight excreted materials. In a similar manner, the high molecular weight materials were isolated from the reservoir water. These materials were analysed for metal complexation with Cu and Cd, monosaccharide composition and elemental analysis (C, H, N and S). In the reservoir water, Cd speciation was dominated by ionic species, while Cu was mostly associated to the dissolved organic matter. Seasonal samplings presented Cu ligands with similar complexation parameters for the entire period studied. Cd complexation was not detected in the reservoir water. The speciation model resulted in similar Cu2+ concentration to the mean value obtained in field analyses, and indicated higher Cu association to the ligands of the reservoir water. Cu was complexed by all high molecular weight materials studied, while Cd was complexed solely by the cyanophyte materials. Higher proportions of acid monosaccharides in the high molecular weight materials corresponded to higher Cu and Cd complexation parameters, whereas no relation between C, H, N and S proportions and metal complexation properties of the high molecular weight materials was observed. The excreted materials of dominant microalgae from Barra Bonita reservoir had Cu ligands with intermediate to weak binding strength, as those present in the reservoir water. These results indicate the potential influence of such organic materials in metal speciation, bioavailability and mobility of metals with similar behaviour to that of Cu in the reservoir water. / A influência do fitoplâncton e de seus produtos excretados resultantes da fotossíntese em corpos d'água têm sido o enfoque de vários trabalhos que investigam a especiação e o destino de metais. Este estudo teve como hipótese a potencial influência dos materiais de alta massa molecular excretados por três espécies fitoplanctônicas (Anabaena spiroides, Microcystis aeruginosa e Aulacoseira granulata), dominantes no reservatório de Barra Bonita, em relação à especiação e complexação dos metais Cu e Cd na água do reservatório. Para tanto o estudo foi dividido em investigações de campo e experimentos de laboratório. Coletas sazonais por um período de dois anos no reservatório foram avaliadas quanto às espécies dissolvidas totais, orgânicas e iônicas de Cu e Cd, a determinação dos parâmetros de complexação destes metais com ligantes presentes na água, assim como o conteúdo de carbono orgânico dissolvido e os parâmetros físico-químicos da coluna d água. Uma modelagem da especiação química dos metais estudados foi feita com o uso das concentrações totais e os parâmetros de complexação adquiridos nas coletas sazonais. No laboratório foram obtidos os materiais de alta massa molecular excretados em cultivos das microalgas selecionadas, e o material de alta massa molecular dissolvido na água do reservatório, isolado seguindo-se o mesmo procedimento usado para os excretados algais. Estes materiais foram analisados quanto aos parâmetros de complexação com Cu e Cd, e composição monossacarídica e elementar (C, H, N e S). A especiação do Cd na água do reservatório foi dominada por formas iônicas, enquanto o Cu estava em grande maioria associado à matéria orgânica dissolvida. A água do reservatório apresentou, nas coletas sazonais, ligantes para Cu com parâmetros de complexação semelhantes em todo o período estudado. Nas condições experimentais empregadas, não foi detectada a complexação de Cd com ligantes oriundos da água do reservatório. A modelagem da especiação de Cu resultou em uma concentração semelhante de Cu2+ àquela medida em amostras de campo, e maior associação do Cu aos ligantes caracterizados neste estudo. O Cu foi complexado tanto pelos materiais de alta massa molecular das microalgas como também pela água do reservatório, enquanto o Cd foi complexado somente pelo material excretado pelas cianofíceas. Maiores proporções de monossacarídeos ácidos nos materiais corresponderam a parâmetros de complexação de Cu e Cd com valores mais elevados. No entanto, não foi observada uma relação entre as proporções de C, H, N e S e a complexação dos metais. Os excretados das microalgas dominantes no reservatório apresentaram ligantes para Cu com força de associação de intermediária a fraca, assim como os ligantes presentes no reservatório. Estes resultados confirmam o potencial de influência dos excretados na especiação, mobilidade e destino de metais com comportamento semelhante ao Cu, no reservatório de Barra Bonita.