Submitted by RAPHAEL MAZZINE BARBOSA DE OLIVEIRA (mazzine.r@gmail.com) on 2018-08-31T12:54:04Z No. of bitstreams: 1 DISSERTACAO_RMAZZINE.pdf: 2481284 bytes, checksum: e17b453dc770c4f6b899c9c0a5de342a (MD5) / Approved for entry into archive by Ana Carolina Gonçalves Bet null (abet@iq.unesp.br) on 2018-09-05T12:38:02Z (GMT) No. of bitstreams: 1 oliveira_rmb_me_araiq_int.pdf: 2195098 bytes, checksum: 013fbe713d5edbed6ff4d629e660b906 (MD5) / Made available in DSpace on 2018-09-05T12:38:02Z (GMT). No. of bitstreams: 1 oliveira_rmb_me_araiq_int.pdf: 2195098 bytes, checksum: 013fbe713d5edbed6ff4d629e660b906 (MD5) Previous issue date: 2018-08-21 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Desde a primeira descrição de biossensor reportada por Clark e Lyons em 1962, houve um extenso trabalho no desenvolvimento e aprimoramento de novas técnicas de biossensoriamento para detecção de biomarcadores com relevância médica. Destaca-se nesse processo o estudo de superfície de eletrodos, pois esse influencia diretamente em aspectos como; sensibilidade, estabilidade e qualidade do sinal. Portanto, este projeto consiste em avaliar comparativamente três superfícies de eletrodos baseadas em nanoestruturas contendo nanopartículas de azul da Prússia, funcionando com sonda redox do sistema, e materiais carbonáceos (como óxido de grafeno e nanotubos de carbono) para aplicação em biossensores. Foram avaliados aspectos como composição, características capacitivas redox e estabilidade de sinal. A técnica de análise utilizada é a espectroscopia de capacitância eletroquímica (ECE) que apresenta vantagens como não usar amplificadores de sinal (sondas redox) em solução, configuração esta, importante para métodos de diagnóstico point-of-care. Das superfícies analisadas, a composta por nanopartículas de azul da Prússia e óxido de grafeno (PBNP+GO) apresentou os melhores parâmetros de estabilidade e compatibilidade com os aspectos teóricos da técnica de ECE, sendo então selecionada para realização de testes de biossensoriamento que, através da funcionalização da superfície com anticorpos Anti-IL-6, detectaram seletivamente a presença do biomarcador IL-6. / Since the first description of biosensor reported by Clark and Lyons in 1962, numerous works related to the development and enhancement of novel medical biosensing techniques have been published. In that context, it must be highlighted the study of electrode surfaces as it has direct influence in aspects like; sensitivity, stability and signal quality. Therefore, this project aims to evaluate three electrode surfaces based on nanostructures with Prussian blue nanoparticles, as redox probe, and carbonaceous materials (like graphene oxide and carbon nanotubes) and their application in biosensors. It was evaluated aspects like composition, redox capacitive characteristics and signal stability. The electrochemical capacitance spectroscopy technique (ECE) was used as it offers several advantages like no need of signal amplifiers (redox probes) in solution and, then, making this technique more adequate for point-of-care diagnosis. Among the analysed surfaces, the one composed by Prussian blue nanoparticles and graphene oxide (PBNP+GO) was identified as the best surface in terms of stability and compatibility to the theoretical aspects of ECE. Therefore, that structure was selected to further biosensing essays, by functionalizing the surface with Anti-IL-6 antibodies, that indicated the selective detection of the IL-6 biomarker. / 1583843

Nesta dissertação estudou-se a influência dos parâmetros de pós-tratamento eletroquímico, em condições potenciodinâmicas, sobre a estabilidade e reatividade frente à organofosfatos do filme eletrodepositado de hexacianoferrato (II) de ferro (III), mais conhecido como azul da Prússia (PB). O pós-tratamento do filme em baixas velocidades de varredura leva à formação do PB \"solúvel\" com a formação de grãos maiores e um filme mais estável eletroquimicamente como demonstrado por ensaios de voltametria cíclica (VC), microscopia de força atômica (AFM) e espectroscopia de fotoelétrons excitados por raios X (XPS). Filmes pós-tratados em meio HCl/KCl 0,1M foram mais eletroquimicamente estáveis em meio ácido, enquanto filmes submetidos à pós-tratamento em meio neutro foram mais estáveis em meio neutro. / In this work it was studied the influence of the electrochemical posttreatment parameters in potenciodinamics conditions on the stability and reactivity against organophosphates by eletrodepositaded iron (III) hexacyanoferrate (II), better known as blue of Prussia (PB). The posttreatment of the film at low sweep rates leads to the formation of the PB \"soluble\" with the formation of larger grains and a more electrochemically stable films as demonstrated by cyclic voltammetry (VC), atomic force microscope (AFM) and X-ray photoelectron espectroscopic (XPS) tests. Films post-treated in HCl/KCl 0.1 M media were more electrochemically stable in an acid media, while films submitted to post-treatment in neutral media were more stable in neutral media.

Orientador: Juliano Alves Bonacin / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Química / Made available in DSpace on 2018-08-26T03:08:14Z (GMT). No. of bitstreams: 1 Pires_BrunoMorandi_M.pdf: 2407620 bytes, checksum: 2e530d02b80b21bc630f85382a3a4ece (MD5) Previous issue date: 2014 / Resumo: Complexos de cianoferratos receberam destaque na década de 70, com a investigação de suas estruturas eletrônicas e reatividade. Estas espécies possuem grande afinidade por compostos N-heterocíclicos, aminoácidos, sulfóxidos, tio éteres e tioamidas. A modificação com diferentes ligantes permite a modulação suas propriedade e reatividade. Esses complexos também podem produzir o azul da Prússia, que é um mimético da enzima peroxidase. Neste trabalho, foi sintetizado o complexo de pentacianoferrato (II) [Fe(CN)5(isn)]4- (isn= 4carboxilatopiridina ou isonicotinato), que devido a sua labilidade, foi utilizado na obtenção filmes de azul da Prússia a partir de deposição sobre eletrodos de carbono vítreo. Os filmes utilizados foram utilizados na determinação eletrocatalítica de ácido ascórbico, que é um analito de interesse biológico e industrial. A caracterização do complexo foi realizada através de espectroscopia eletrônica UV-Vis e espectroscopia vibracional na região do infravermelho, cujo espectro vibracional teórico apresentou grande concordância com os resultados experimentais, o que reforça a identidade do produto obtido. Outra técnica utilizada na caracterização do complexo foi a voltametria cíclica. Experimentos de cinética de substituição do ligante N-heterocíclico mostram que a reação de troca por DMSO ocorre por mecanismo dissociativo, com parâmetros cinéticos e termodinâmicos em concordância com complexos análogos descritos na literatura. A partir do complexo sintetizado foi possível obter filmes finos de azul da Prússia pelo método potenciostático. Esses filmes, estáveis em pH 3,0 e 5,0, foram utilizados na oxidação eletrocatalítica de ácido ascórbico, apresentando resposta linear na determinação deste analito. Também foi observada variação do potencial de pico anódico com o aumento do valor do pH. Com estes resultados, conclui-se que os filmes obtidos por essa metodologia tem grande potencial na construção de sensores eletroquímicos / Abstract: Cyanoferrate complexes have received attention in the 1970¿s, mainly the investigation of their electronic structures and reactivity. These species have a great affinity for N-heterocyclic compounds, amino acids, sulfoxides, thioethers and thioamides. The modification with different ligands allows the modulation of their properties and reactivities. These complexes can also produce Prussian blue, which is a well-known mimetic of peroxidase enzyme. In this work, the pentacyanoferrate (II) complex [Fe(CN)5(isn)]4- (isn = 4-carboxilatepyridine or isonicotinate), which reactivity was used to obtain Prussian blue films deposited on the surface of glassy carbon electrodes. The films were used in the electrocatalytical quantification of ascorbic acid, which is a very important analyte with industrial and biological importance. The characterization of the complex was performed using UV-Vis and infrared spectroscopy, which theoretical calculation showed good agreement with experimental data. Also, cyclic voltammetry was used to determine the electrochemical properties of the complex. Substitution kinetics of the N-heterocyclic ligand indicated that the switch for DMSO occurs by a dissociative mechanism, with kinetic and thermodynamic parameters in agreement with analog complexes described in literature. The synthesized complex was used to obtain thin Prussian blue films by the potentiostatic method. These films, which were stable at pH 3.0 and 5.0, were used in the catalytical electrooxidation of ascorbic acid, showing linear response for the determination of this analyte. Another interesting feature of this system is the variation of the anodic peak potential with pH change. From these results, it was possible to conclude that the films obtained using this methodology have great potential in the construction of electrochemical sensors / Mestrado / Quimica Inorganica / Mestre em Química

Les propriétés des nanotubes de carbone monoparois (SWCNTs) dépendent fortement de leur structure atomique. La croissance sélective en structure des SWCNTs est donc un objectif clé à atteindre pour les applications potentielles de ces matériaux uniques. Dans le travail présenté dans ce manuscrit, nous proposons une nouvelle méthode originale alliant chimie de coordination et chimie des surfaces, pour la croissance de SWCNTs par décomposition chimique en phase vapeur, à partir de pré­ curseurs de catalyseurs variés synthétisés par voie chimique.L 'étude approfondie de ce procédé est présenté pour trois systèmes métalliques de précurseurs (Fe, NiFe, NiCr), issus de la famille du bleu de Prusse. Une caractérisation détaillée des précurseurs, catalyseurs, et des SWCNTs synthétisés a permis de mettre en évidence des effets de la composition du catalyseur sur les phénomènes de croissance.Une étude comparative de microscopie électronique en transmission et de spectroscopie Raman pour la détermination de la distribution de diamètre des échantillons de SWCNTs obtenus a été effectuée, mettant en lumière l 'importance primordiale du recours à des caractérisations croisées pour l 'évaluation de la sélectivité des croissances.Enfin, d'autres pistes de précurseurs de catalyseurs synthétisés par voie chimique sont explorées. Des résultats préliminaires sur deux systèmes bimétalliques de précurseurs issus de la famille des « cyanosols » (FePd) , et de celle des polyoxometallates (CoW) sont présentés, soulignant leur intérêt pour la compréhension des mécanismes complexes de croissance des SWCNTs. / The work presented in this manuscript is focused on the study of single-walled carbon nanotube (S WCNT) growth by chemical vapor deposition, through the tuning of catalyst nanoparticle composition. The properties of S WCNTs strongly depend on their atomic structure, making structurally selective growth essential for future applications. Here we present a new and original method combining surface chemistry and coordination chemistry, for S CNT growth using a wide range of mono- and bimetallic catalyst systems, formed by the reduction of chemically synthesized catalyst precursors.A thorough study of this process is presented for three metallic precursor systems (Fe, NiFe, NiC), derived from the Prussian blue compound family. An extensive characterization of the precursors, ca­ -talysts, and the resulting S CNTs has allowed to evidence effects of catalyst composition on growth phenomena.We also show the importance of cross-characterization of SWCNT growth samples, through a comparative study between TEM, and Raman spectroscopy for diameter distribution assessment of our growth samples, and on diameter-sorted SWCNT samples.Preliminary results on the use of cyanosols and polyoxomet alates for SWCNT growth with additional bimetallic catalyst systems (FePd , and CoW) are also presented , highlighting the rich potential of inorganic chemistry and coordination chemistry in the field of SWCNT growth .

The aim of this project was to find a recycling route for Prussian white. During the experimental part, one recycling method was tested using sodium hydroxide and from this a method for re-synthesis of Prussian white was conducted as well as a method for re-crystallisation of sodium ferrocyanide. The method that proved most successful was the re-crystallisation of sodium ferrocyanide. Furthermore, the conditions needed to conduct a proper re-synthesis of Prussian white was not available during this research. Therefore, it was not possible to produce Prussian white of the right structure. The analysis was performed through XRD analysis and it was concluded that it is possible to re-crystallise sodium ferrocyanide from Prussian white.

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The discovery and dissemination of new knowledge are essential in food science. To advance our understanding of fruit chemistry, analytical methods were compared and applied. Polyphenols are secondary metabolites in fruits of particular importance in food science, as they contribute to the sensory attributes and health benefits of the products. Evaluation of common analytical methods for the quantification of polyphenols, including the Folin-Ciocalteu (F-C), Lowenthal permanganate (L-P), 4-dimethylaminocinnamaldehyde (DMAC) and the bovine serum albumin (BSA) precipitation methods, was conducted using analytical method validation procedures. The F-C method was not specific to polyphenols, and the L-P method had the widest working range but lacked accuracy. The DMAC method was the most specific to flavanols, and the BSA method was not suitable for quantification of smaller flavanols. Quantitative performance of these four methods was evaluated using a broad range of fruit-derived samples. Variation in quantitative results obtained using these four methods was explained by differences in polyphenol and matrix composition of these samples and differences in operating principles of the methods. The reactivity of individual polyphenol compounds (catechin, epicatechin, PC B2, PC pentamer, chlorogenic acid, phloretin, and quercetin) to the polyphenol and flavanol quantification results using Prussian blue (P-B), F-C, DMAC and BSA precipitation methods were also assessed and determined to differ by up to thirteen-fold, depending on the assay. Furthermore, the contribution and interactions of polyphenol compounds (catechin, PC B2, and chlorogenic acid) and potentially interfering compounds likely to be found in fruit and fruit products (ascorbic acid, glucose, and SO2) to the quantitative results of these methods were evaluated using a full factorial design. Significant interactions among polyphenol compounds, and among the interfering compounds were found. The standardized coefficient (β) for all factors and interactions of polyphenol compounds varied from 0.347 to 129, and from near 0 to -46.8 for all factors and interactions of interfering compounds. Our findings indicate that the choice of standards, polyphenol and matrix composition of the sample may cause disparity among the quantitative results of these methods. Amino acids in apple (Malus × domestica Borkh.) juice not only influence the quality of fermented cider through fermentation kinetics but also impact the flavor of the cider through yeast metabolism. Due to recent advances in analytical instrumentation, amino acids profiles in apple juice were determined much faster and more accurately than by previously applied methods. Twenty amino acids were quantified by UPLC-PDA in juices from 13 apple cultivars grown in Virginia. The relative amino acid profile was significantly different among the apple juices evaluated. The total amino acid concentration ranged from 18 mg/L in Blacktwig juice to 57 mg/L in Enterprise juice. L-Asparagine, L-aspartic acid and L-glutamine are the principal amino acids observed in most apple juices. These results will inform future research on yeast metabolism and nitrogen management during cider fermentation. To better disseminate knowledge gained through research to the next generation of food scientists, the effectiveness of new instructional technology—a cellphone-based personal response system—in food science education was evaluated. Students' academic performance was improved by the incorporation of this technology into lectures, and its use was well perceived by the students (easy to use and positively impacted their learning). This finding contributes to the scholarship of teaching and learning in food science by providing useful insight into the potential for application of such tools with improved student engagement and learning outcomes. Advances in food chemistry research will enable the development of value-added food products, and the pedagogical advancement in food science education will better convey new and existing knowledge to students, who will apply this knowledge to promote a safe and nutritious food supply that enhances human health and increases the value of specialty crops. / Doctor of Philosophy / In food science, both the discovery and dissemination of new knowledge are essential. To advance our understanding in fruit chemistry, several analytical methods were compared and applied. Polyphenols are important bioactive compounds in fruits associated with health benefits, and they also contribute to the bitterness and astringency of the products such as chocolate and red wines. Systematic evaluation of common analytical methods used to quantify polyphenols was conducted. When different methods were used to evaluate a broad range of fruit-derived samples, different results were obtained for a given sample, depending on the method applied. This was explained by the difference in polyphenol composition of these samples. Furthermore, different individual polyphenol compounds contributed differently to quantitative results for these methods. Interactions among polyphenol compounds and interference from constituents of the juice samples other than polyphenols were also found. These findings demonstrate that when comparing fruit chemistry (polyphenol concentration) results obtained using the methods evaluated, it is necessary to consider the polyphenol composition as well as the sample matrix composition. This knowledge will improve our ability to interpret and compare existing data on polyphenol content in fruits, advancing the understanding the polyphenols and health and informing producers to improve their fruit products with optimized quality and sensory characters. Secondly, amino acids in apple juice influence the quality of fermented cider, through not only controlling the fermentation rate, but also impacting the flavor of the cider through yeast metabolism. Twenty amino acids were quantified in juices from 13 apple cultivars grown in Virginia with potential use in cider making using a recently developed method in analytical chemistry. The relative amino acid profile was significantly different among the apple juices evaluated. L-Asparagine, L-aspartic acid and L-glutamine are the principal amino acids observed in most apple juices. This knowledge will help with the development of fermentation strategies for production of ciders with targeted sensory attributes. To better disseminate new knowledge in food science to the next generation, the effectiveness of a new educational technology application—a cellphone-based personal response system (similar to clickers)—in food science education was evaluated. Using this application during lecture resulted in improved quiz grades, and students felt that it was easy to use and positively impacted their learning. This application has the potential to improve effectiveness of lectures in higher education classrooms. Advances in food chemistry research will enable development of value-added food products, and the pedagogical advancement in food science education will better convey new and existing knowledge to students, who will apply this knowledge to promote a safe and nutritious food supply that enhances human health and increases the value of specialty crops.

Dans cette thèse, nous présentons une approche modélisatrice multi-échelles au sein de la théorie de la fonctionnelle densité (DFT) de différentes classes de complexes à propriétés magnétiques commutables essentiellement à base de Fe(II) (3d6). Le manuscrit est organisé en trois grandes parties : la première a été consacrée à la présentation de la chimie théorique (concepts et méthodes). Le magnétisme moléculaire été examiné au travers du calcul de la constante de couplage et discuté dans la partie II. L’analyse de la constante de couplage, du magnétisme, des structures électroniques et des liaisons chimiques a été présentée. D’autre part, l’étude des valeurs thermodynamiques pour [Fe(btz)2(NCS)2] ainsi que la famille de complexes à transition de spin [Fe(L)2(NCS)2] a formée la troisième partie. De deux approches complémentaires sont utilisées: i-moléculaire où l’entité isolée est examinée en utilisant des codes de calcul ciblés moyennant différentes fonctionnelles d’échange corrélation et bases ; ii-« tout solide » prenant en compte la structure cristalline étendue. Les résultats sont également appuyés par une étude semi-empirique au sein de la dynamique moléculaire / In this thesis, we present an multiscale approaches based on theoretical modeling within density functional (DFT) of different classes of complex magnetic properties switched from predominantly Fe(II) (3d6). The manuscript is organized into three main parts: the first was devoted to the presentation of theoretical chemistry (concepts and methods). The molecular magnetism was examined through the calculation of the coupling constant and discussed in Part II. The analysis of the coupling constant, magnetism, electronic structure and chemical bonds was presented. In the third Part, the study of thermodynamic values for [Fe(btz)2(NCS)2] and the family of spin crossover complexes [Fe(L)2(NCS)2] has formed the third party. Two complementary approaches are used: i-“molecular” which considers a fragment entity or isolated molecule using different computer codes targeted through various exchange correlation functional and basis; ii-"solid state" taking into account the extended crystal structure. The results are also supported by a semi-empirical study through molecular dynamics.