A major problem in the quantitative analysis of AC voltammetric data has been the variance in results between laboratories, often resulting from a reliance on "heuristic" methods of parameter estimation that are strongly dependent on the choices of the operator. In this thesis, an automatic method for parameter estimation will be tested in the context of experiments involving electron-transfer processes in solution-phase. It will be shown that this automatic method produces parameter estimates consistent with those from other methods and the literature in the case of the ferri-/ferrocyanide couple, and is able to explain inconsistency in published values of the rate parameter for the ferrocene/ferrocenium couple. When a coupled homogeneous reaction is considered in a theoretical study, parameter recovery is achieved with a higher degree of accuracy when simulated data resulting from a high frequency AC voltammetry waveform are used. When surface-confined reactions are considered, heterogeneity in the rate constant and formal potential make parameter estimation more challenging. In the final study, a method for incorporating these "dispersion" effects into voltammetric simulations is presented, and for the first time, a quantitive theoretical study of the impact of dispersion on measured current is undertaken.

Made available in DSpace on 2017-07-20T12:40:16Z (GMT). No. of bitstreams: 1 Alvaro Fontana.pdf: 7055530 bytes, checksum: 4a9069c1fa7120a7895a1587f1fe173e (MD5) Previous issue date: 2015-09-18 / Fundação Araucária de Apoio ao Desenvolvimento Científico e Tecnológico do Paraná / In this work were performed organic synthesis of the monomer derivatives of poly (p-phenylenevinylene) whose main interest was to obtain a monomer with an aromatic ring having attached two bromine atoms (this step not being performed), a cyano group, a side chain of six carbon atoms and a sulfonic group linked to the end of side chain. The syntheses were performed starting from the compound 2,5-dimethylphenol and adding the aromatic ring an iodine atom, made subsequently replacing the iodine atom by a cyano group, and the sequences of reactions by adding a side chain with six carbon atoms attached at its one end a sulfonic group. The characterization of the obtained compounds was performed by spectroscopy techniques, Infrared, nuclear magnetic resonance 1H and 13C and GC-MS. These analyzes showed that the structures of the proposed monomers were achieved almost entirely. Part of this doctoral work was performed in the laboratory of the Emeritus Professor Dr. Alan Maxwell Bond at Monash University, Melbourne - Australia, such as sandwich doctorate program. The study in Australia comprised learning and application of cyclic voltammetry technique ac coupled to Fourier transform in chemical reactions studying the kinetics of 1 and 2 electron transfer, in this case, taking as an example the molecule N,N,N',N'-Tetramethyl-p-phenylenediamine, TMPD. The molecular solvents used for the study of electron transfer in the molecule TMPD were acetone and acetonitrile, and the following ionic liquids: [BMPIPTFSI], [BMIM] [TFSI], [BMIm][BF4] and [BDMIM] [TF2N]. In all the results obtained it was found the process known as internal reference, where the first electron transfer reaction in the molecule, because it is faster, can be used to compare the values of the thermodynamic and kinetic parameters obtained in the first process with the parameter values obtained in the second electron transfer process in the same molecule. / Neste trabalho foram realizadas sínteses orgânicas de monômeros derivados de poli(p-fenilenovinileno) cujo principal interesse foi a obtenção de um monômero com um anel aromático tendo ligado a ele, dois átomos de bromo (não sendo realizada essa etapa), um grupamento ciano, uma cadeia lateral com seis átomos de carbono, e um grupamento sulfônico ligado a extremidade da cadeia lateral. As sínteses foram realizadas partindo-se do composto 2,5-dimetilfenol e adicionando-se ao anel aromático um átomo de iodo, posteriormente feita a troca do átomo de iodo por um grupo ciano e nas sequências das reações adicionando-se uma cadeia lateral com seis átomos de carbono oposta ao grupo ciano e ligado na extremidade da cadeia lateral um grupo sulfônico. A caracterização dos compostos foi realizada através das técnicas, infravermelho, ressonância magnética nuclear 1H, 13C e CG-MS. Essas análises evidenciaram que as estruturas dos monômeros propostos foram alcançadas em quase sua totalidade. Parte deste trabalho de doutoramento foi realizada no laboratório do professor Emeritus Dr. Alan Maxwell Bond na Monash University em Melbourne – Austrália, como doutorado sanduíche. O estudo feito na Austrália compreendeu a aprendizagem e aplicação da técnica de voltametria cíclica ac acoplada à transformada de Fourier, estudando-se a cinética de transferência de 1 e 2 elétrons, neste caso, utilizando-se como exemplo, a molécula N,N,N′,N′-Tetramethyl-p-phenylenediamine, TMPD. Os solventes moleculares utilizados para o estudo da transferência de elétrons nesta molécula foram acetona e acetonitrila e também os seguintes líquidos iônicos: [BMPIPTFSI], [BMIM][TFSI], [BMIm][BF4] e [BDMIM][TF2N]. Em todos os resultados obtidos constatou-se o processo chamado de referência interna, onde, a primeira reação de transferência de elétrons nesta molécula, por ser mais rápida, pode ser utilizada para comparar os valores dos parâmetros termodinâmicos e cinéticos obtidos no primeiro processo de transferência de elétrons com os valores dos parâmetros obtidos no segundo processo na mesma molécula.

Made available in DSpace on 2017-07-24T19:37:54Z (GMT). No. of bitstreams: 1 Alvaro Fontana.pdf: 7055530 bytes, checksum: 4a9069c1fa7120a7895a1587f1fe173e (MD5) Previous issue date: 2015-09-18 / Fundação Araucária de Apoio ao Desenvolvimento Científico e Tecnológico do Paraná / In this work were performed organic synthesis of the monomer derivatives of poly (p-phenylenevinylene) whose main interest was to obtain a monomer with an aromatic ring having attached two bromine atoms (this step not being performed), a cyano group, a side chain of six carbon atoms and a sulfonic group linked to the end of side chain. The syntheses were performed starting from the compound 2,5-dimethylphenol and adding the aromatic ring an iodine atom, made subsequently replacing the iodine atom by a cyano group, and the sequences of reactions by adding a side chain with six carbon atoms attached at its one end a sulfonic group. The characterization of the obtained compounds was performed by spectroscopy techniques, Infrared, nuclear magnetic resonance 1H and 13C and GC-MS. These analyzes showed that the structures of the proposed monomers were achieved almost entirely. Part of this doctoral work was performed in the laboratory of the Emeritus Professor Dr. Alan Maxwell Bond at Monash University, Melbourne - Australia, such as sandwich doctorate program. The study in Australia comprised learning and application of cyclic voltammetry technique ac coupled to Fourier transform in chemical reactions studying the kinetics of 1 and 2 electron transfer, in this case, taking as an example the molecule N,N,N',N'-Tetramethyl-p-phenylenediamine, TMPD. The molecular solvents used for the study of electron transfer in the molecule TMPD were acetone and acetonitrile, and the following ionic liquids: [BMPIPTFSI], [BMIM] [TFSI], [BMIm][BF4] and [BDMIM] [TF2N]. In all the results obtained it was found the process known as internal reference, where the first electron transfer reaction in the molecule, because it is faster, can be used to compare the values of the thermodynamic and kinetic parameters obtained in the first process with the parameter values obtained in the second electron transfer process in the same molecule. / Neste trabalho foram realizadas sínteses orgânicas de monômeros derivados de poli(p-fenilenovinileno) cujo principal interesse foi a obtenção de um monômero com um anel aromático tendo ligado a ele, dois átomos de bromo (não sendo realizada essa etapa), um grupamento ciano, uma cadeia lateral com seis átomos de carbono, e um grupamento sulfônico ligado a extremidade da cadeia lateral. As sínteses foram realizadas partindo-se do composto 2,5-dimetilfenol e adicionando-se ao anel aromático um átomo de iodo, posteriormente feita a troca do átomo de iodo por um grupo ciano e nas sequências das reações adicionando-se uma cadeia lateral com seis átomos de carbono oposta ao grupo ciano e ligado na extremidade da cadeia lateral um grupo sulfônico. A caracterização dos compostos foi realizada através das técnicas, infravermelho, ressonância magnética nuclear 1H, 13C e CG-MS. Essas análises evidenciaram que as estruturas dos monômeros propostos foram alcançadas em quase sua totalidade. Parte deste trabalho de doutoramento foi realizada no laboratório do professor Emeritus Dr. Alan Maxwell Bond na Monash University em Melbourne – Austrália, como doutorado sanduíche. O estudo feito na Austrália compreendeu a aprendizagem e aplicação da técnica de voltametria cíclica ac acoplada à transformada de Fourier, estudando-se a cinética de transferência de 1 e 2 elétrons, neste caso, utilizando-se como exemplo, a molécula N,N,N′,N′-Tetramethyl-p-phenylenediamine, TMPD. Os solventes moleculares utilizados para o estudo da transferência de elétrons nesta molécula foram acetona e acetonitrila e também os seguintes líquidos iônicos: [BMPIPTFSI], [BMIM][TFSI], [BMIm][BF4] e [BDMIM][TF2N]. Em todos os resultados obtidos constatou-se o processo chamado de referência interna, onde, a primeira reação de transferência de elétrons nesta molécula, por ser mais rápida, pode ser utilizada para comparar os valores dos parâmetros termodinâmicos e cinéticos obtidos no primeiro processo de transferência de elétrons com os valores dos parâmetros obtidos no segundo processo na mesma molécula.

The aminoacid sequence of papain (EC 3.4.22.2) consists of 212 aminoacids. It has only one free sulfhydryl group, which is located in the active site of the protein. Some organometallic complexes could be bonded only to this free -SH group due to their structure. The artificial metalloproteins synthesised by this way may have different electrochemical properties. In this work, we have studied the electrochemical properties of papain and its derivatives. We compared the ability of papain and its three artificial derivatives to catalyse the hydrogen evolution by the chronopotenciometry. The work was completed by the study of the electrochemical properties of the organometallic complexes of ruthenium, which were used for the artificial metalloprotein preparation. The electrochemical properties of the compounds were never studied before. The process of the hydrogen evolution catalysed by the proteins is held in the adsorbed state of the catalyst. Due to this fact we have also studied the adsorption properties of papain on the substrates with different level of hydrofobicity. (In Czech)

L’objectif de cette thèse était de mettre au point une interface électrochimique afin de caractériser les interactions entre le cytochrome c (cyt c), une protéine mitochondriale, et le cardiolipide (CL), un phospholipide présent dans les membranes des mitochondries. Le cyt c, dont la fonction est le transport d'électrons dans la chaîne respiratoire, est connu pour interagir avec le CL. Précédemment, un mécanisme d'accroche du cyt c sur une membrane contenant du CL a été mis en évidence par la théorie de l’« extented lipid anchorage ». Cette théorie prévoit, outre des interactions électrostatiques entre le CL (chargé négativement) et le cyt c (chargé positivement), des interactions hydrophobes issues de l'insertion d'une chaîne grasse du CL dans le cyt c. La nature particulière de la partie hydrophobe du CL, quatre chaines grasses dont la composition est très homogène, nous a amenés à émettre des hypothèses sur la présence d'interactions spécifiques entre le cyt c et différents types de chaines du CL. Dans le cadre de mes travaux, des techniques électrochimiques ont été utilisées pour étudier ces interactions. Une électrode de carbone vitreux a été modifiée par un dépôt de phosphatidylcholine (PC) et de CL en proportion 80/20 (mol/mol). Cette électrode modifiée au CL permet l'étude de l'électrochimie du cyt c. Nous avons montré que l’électroactivité du cyt c nécessite la présence de CL sur l'électrode modifiée, le cyt c étant électroinactif sur une électrode modifiée uniquement avec de la PC. De plus, le CL permet de retenir le cyt c à la surface de l'électrode. C'est la première fois que l'effet de « lipid anchorage » a été identifié sur une électrode modifiée. Une méthode électrochimique plus adaptée à l'étude des protéines adsorbées (AC voltamétrie) a été utilisée afin de caractériser les cinétiques de transfert électronique du cyt c. Par cette méthode, deux sous-populations de cyt c adsorbés ont été caractérisées. La sous-population 1 de cyt c, qui est majoritaire, possède un potentiel redox proche du potentiel du cyt c en solution (0V vs SCE). Sa vitesse de transfert électronique est de l'ordre de 20s-1. La sous-population 2, qui compte pour environ 10% du cyt c adsorbé total, possède un potentiel décalé vers les valeurs négatives (-0.15V vs SCE) et une vitesse de transfert électronique supérieure à la sous-population 1 (environ 500s-1). Afin de mieux cerner le type d'interaction dans ces deux sous-populations, l'effet d'une solution de forte force ionique (0.5M KCI), du pH, du calcium, de la classe de phospholipide ou de l'origine du cyt c a été testé. Ces expériences ont démontré que la sous-population 1 comporte des interactions de type électrostatiques et nécessite la présence d'un phospholipide ayant un motif glycérol terminal (comme le CL ou la PG), La nature de l'interaction protéine-lipide pour la sous-population 2 est plus complexe. Elle est sensible aux cations divalents ou au pH mais insensible aux fortes forces ioniques, laissant supposer la présence d'interactions de type hydrophobe.Les essais réalisés avec du cyt c de levure laissent entrevoir qu'il existe des spécificités entre cette protéine et les phospholipides d’un même organisme. La purification de cyt c de bivalve permettrait d'avancer pour valider cette hypothèse. / The main goal of this thesis was to set up an electrochemical interface in order to characterize interactions between cytochrome c (cyt c), a mitochondrial protein, and cardiolipin (CL), a phospholipid localized to the mitochondrial membrane.The cyt c, whereas the main function is to carrying electrons along the respiratory chain, is known to interact with CL.Previously, a mechanism of cyt c retention onto a CL containing membrane was highlighted by the “extended lipid anchorage” theory. This theory imply, with electrostatic interactions between CL (negatively charged) and cyt c (positively charged), the presence of hydrophobic interaction likely emanating from the insertion of an acyl chain of CL into the cyt c interior. The specificity of the hydrophobic moiety of CL, constituted of four similar chains lead us to make hypothesis about specific interactions between cyt c and acyl chains of CL. Attention have been made to the bivalves CL acyl chains carrying unique composition of 8O% DHA chains.Electrochemicals techniques have been used to study these interactions. A glassy carbon has been modified with a deposit by spin-coating of phosphatidylcholine (PC) and CL in 80/20 ratio (mol/mol). This CL modified electrode allows the study of the cyt c electrochemistry. Firstly, we showed that electroactivity of cyt c require the presence of CL onto the modified electrode meaning cyt c isn't electroactive on a modified electrode with PC only. ln add, CL allows retaining cyt c onto the electrode surface. lt is the first time that this lipid anchorage has been identified on a modified electrode.Electrochemical methods adapted to the study of adsorbed protein (AC voltametry) have been used in order to characterize the electrode transfer kinetics of cyt c. With these methods, two sub-populations of adsorbed cyt c have been characterized. The major part of cyt c, called sub-population 1, has a redox potential close to the formal potential of the native protein (around 0Vvs SCE). Electron transfer rate is in the range of 20s-1. The subpopulation 2, counting for ~10% of the total adsorbed cyt c, hold a negative shifted potential around -0.15V vs SCE and a faster electron transfer rate (~500s-1).To understand the nature of the interaction for the two subpopulations, the effect of an high ionic strength solution (0.5M KCI), pH, calcium, phospholipids classes or cyt c sources have been assayed. These tests shows that subpopulation t have electrostatics interactions and require the presence of a phospholipid holding a terminal glycerol pattern like PG or CL.The nature of the protein-lipid interaction in the case of the subpopulation 2 is more complex. lt is more sensitive to the presence of divalent cation or pH but high ionic strength solution doesn't affect it. This could be explained by hydrophobic interactions between lipid and the cyt c.The assays realized with cyt c from yeast let foresee specificity between these protein and the phospholipids carried by the same organism. The purification of bivalve cyt c could be a progress in order to validate this hypothesis.