Made available in DSpace on 2016-06-02T19:19:58Z (GMT). No. of bitstreams: 1 SOUZA_Tamera_2014.pdf: 3828061 bytes, checksum: 5a203182c573895f9074200bb9448449 (MD5) Previous issue date: 2014-02-24 / Financiadora de Estudos e Projetos / The layer-by-layer technique is one of the most used in the immobilization of molecules of biological interest, being largely employed in the fabrication of modified electrodes for biosensors. One of the main challenges in the development of biosensors is to eliminate interfering electroactive species within the detection system, therefore, this problem can be solved with the introduction of inorganic or organic electron mediators. Here, we carried out systematic studies for the application of hemoglobin acting as an electron mediator, and the self-assembly technique was used to immobilize haemoglobin in nanostructured thin films. The LbL films were tested with two polyelectrolytes, obtaining uniform films with activity kept during 15 days, without responses to possible interfering phospholipids. The layer-bylayer technique was also used to immobilize the enzyme cholesterol oxidase, alternated with different polyelectrolytes. The thin films showed a good performance as an amperometric biosensor for the detection of cholesterol at low concentrations (10-5 M), with the functioning of the biosensor attributed to the use of hemoglobin in mediating the effects of excluding interfering ascorbic acid and uric acid. Some tests were also performed in real samples using egg yolk, with good results obtained. The high sensitivity and selectivity of the biosensor have been attributed to the nanostructured thin nature of the films, despite recognition capability of the biomolecules used, with a strong potential to contribute for new device technologies for food analysis. / A técnica de automontagem ou layer-by-layer é uma das mais utilizadas na imobilização de moléculas de interesse biológico. Essa técnica é empregada na fabricação de eletrodos modificados utilizados, como por exemplo, os biossensores. Um dos desafios no desenvolvimento de biossensores é eliminar interferentes de espécies eletroativas dentro do sistema de detecção. Esse problema pode ser solucionado com a introdução de mediadores de elétrons inorgânicos ou orgânicos. Nessa dissertação foram realizados estudos sistemáticos para a aplicação da hemoglobina atuando como mediadora de elétrons. A técnica de automontagem foi utilizada para a imobilização da hemoglobina, testada com dois polieletrólitos, obtendo filmes uniformes, mantendo sua atividade por 15 dias e sem respostas aos possíveis interferentes fosfolipídios. A automontagem também foi utilizada para imobilizar a enzima colesterol oxidase, alternada com diferentes polieletrólitos. Os filmes finos apresentaram um bom desempenho como biossensor amperométrico na detecção de colesterol em baixas concentrações tais como 10-5 M. O bom funcionamento do biossensor deve- se ao emprego da hemoglobina com mediador excluindo os efeitos dos interferentes acido úrico e acido ascórbico. Também foram realizados testes com amostras reais utilizando a gema de ovo obtendo bons resultados. A alta sensibilidade e seletividade dos biossensores foram atribuídas à natureza do filme automontado e à capacidade de reconhecimento das biomoléculas. Este estudo abre caminho para novas tecnologias de dispositivos para análises de alimentos.

Made available in DSpace on 2014-06-11T19:30:19Z (GMT). No. of bitstreams: 0 Previous issue date: 2009-06-19Bitstream added on 2014-06-13T19:39:43Z : No. of bitstreams: 1 kitagawa_il_me_bauru.pdf: 1240008 bytes, checksum: 9ebbdde64d8ef13b31f5e5e5f9a075cc (MD5) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / Esta dissertação apresenta o estudo do crescimento (em escala nanométrica) e morfológica (em escala micrométrica) de filmes finos fabricados segundo a técnica Layer-by-Layer (LbL) contendo ftalocianina tetrasulfonada de níquel, polímeros condutores, o polímero poli(alilamina hidroclorada) (PAH), e gomas naturais. Três sistemas foram investigados: i) filmes LbL de NiTsPc e PAH; ii) filme LbL de NiTsPc, PAH e gomas naturais e iii) filmes LbL dos polímeros condutores polianilina (PANI) e poli(o-metoxianilina) (POMA) com gomas naturais. As gomas utilizadas neste trabalho foram extraídas das árvores cajueiro (Anacardium occidentale), chichá (Sterculia striata), caraia (Sterculia urens) e angico (Anadenanthera macrocarpa Benth). As caracterizações destes filmes foram realizadas por meio das técnicas de espectroscopia eletrônica utilizando absorção na região do ultravioleta-visível (UV-vis), espectroscopia vibracional por espalhamento micro-Raman e por absorção na região do infravermelho (IV) com transformada de Fourier (FTIR). Os resultados deste trabalho mostraram que, somente os filmes de NiTsPc e PAH em pH 8,5 e os filmes de NiTsPc, PAH e gomas naturais apresentaram crescimento controlado, uniformidade morfológica e química. / This dissertation presents the study of growth (in nano-scale thickness) and morphology (micrometric scale) of thin films produced using the Layer-by-Layer technique (LbL) containing nickel tetrasulfonated phthalocyanine, conducting polymers, the polymer poly(allylamine hydrochloride) (PAH), and natural gums. Three systems were investigated: i) LbL films of NiTsPc and PAH; ii) LbL films of NiTsPc, PAH and natural gums and iii) LbL films of the conducting polymers polyaniline (PANI) and poly (o-methoxyaniline) (POMA) with natural gums. The gums used in this work were obtained from the cashew (Anacardium occidentale), chicha (Sterculia striata), caraia (Sterculia urens) and angico (Anadenanthera macrocarpa Benth) trees. The characterizations of the LbL films were made using the ultraviolet-visible (UV-vis) absorption spectroscopy, vibrational spectroscopy through micro-Raman scattering and Fourier Transform infrared (FTIR) absorption. The results showed that only the LbL films of NiTsPc and PAH at pH 8.5 and the LbL films of NiTsPc, PAH and natural gums present controlled growth and morphological and chemical uniformity.

Lors des dix dernières années, les films multicouches ont suscité l’intérêt de la communauté scientifique pour leurs propriétés innovantes. Principalement issus de l’association de polyélectrolytes et/ou de nanoparticules de différentes morphologies, ils ont ouvert la voie à la fabrication d’une nouvelle catégorie de matériaux nanoporeux, possédant des propriétés optiques attractives telles que la coloration structurale et l’antireflet. Les films multicouches à base de deux nanoparticules de charges opposées sont plus rares et permettent de jumeler les propriétés des deux nanoparticules utilisées et d’en faire émerger de nouvelles. Dans cette étude, nous nous sommes intéressés à deux nanoparticules anisotropes, de facteurs d’aspects contrôlés et respectivement bio/geosourcées : les nanocristaux de cellulose (NCC) et des nanotubes d’imogolite. Le but de cette étude est d’étudier la possibilité de créer un film multicouche bio-géo inspiré à base de ces deux nanoparticules par immersion et d’en étudier les propriétés optiques. Dans un premier temps, nous avons comparé les films multicouches NCC/Ge-imogolites à ceux plus communément décrits dans la littérature, à savoir, des films à base de NCC ou d’imogolite associés à un polyélectrolyte de charge opposée. Les différents paramètres de trempage comme le temps d’immersion et la force ionique de la suspension ont été variés afin d’obtenir une densité de film optimale. Pour finir la porosité des films et leur comportement dans l’eau ont été étudiés par QCM-D, ainsi que leurs propriétés optiques par mesure de transmittance. / In the past decade, multilayer thin films drew the scientific community attention for their unique properties. Indeed, principally made of an association of polyelectrolytes and/or nanoparticles, of various morphologies and chemistries, they allow the design of a range of porous nanomaterials with unique optical properties, such as structural colors or anti-reflectivity. Less commonly described, thin films made of two nanoparticles of opposite charges are gaining interest since they combine the properties of the two nanoparticles used, and generate new ones through their association. In this study, multilayer coatings were formed through the association of two anisotropic oppositely charged nanorods of well-controlled aspect ratio, i.e. bio-based anionic cellulose nanocrystals (CNC) and geo-based cationic Imogolites. This study deals with the feasibility to create a bio-geo-inspired multilayer thin film based on these two nanoparticles by dipping and characterize their optical properties. Firstly, elaboration of multilayered thin films from CNC and Ge-Imogolites nanorods, were studied in comparison with reference films incorporating CNC or Imogolites with polyelectrolytes bearing opposite charges of the nanorods. Multilayered thin films were assembled by the dipping procedure and various parameters (adsorption time, ionic strength, etc.) were varied to investigate the optimal density for the film. To finish, film porosities were investigated using QCM-D, and optical properties were investigated by transmittance measurements.

With the growing impact of climate change on both political decisions and how companies develop their products, it is increasingly important to find environmentally friendly alternatives to fossil-based materials. One of the more interesting materials in this respect is cellulose, which is the world's most naturally occurring polymer and can be used in a variety of applications. One way to modify the fibers and to change their properties is to use a method called Layer-by-Layer (LbL) treatment where two polymers of opposite charge are alternately adsorbed to the fiber surface. Another possibility is to oxidize the cellulose in the fibers to obtain a higher charge. This means that the fibers can adsorb a higher amount of cationic additives and that the fibers swell more which means that they are plasticized and can create stronger joints between the fiber surfaces in the dry state, which results in stronger dry fiber networks. However, wood-based fibers are small and inhomogeneous, both chemically and morphologically, which means that it is necessary to use model systems to be able to clarify, in detail, how treated and untreated surfaces interact with each other at a molecular level. One model system that can be used to investigate how cellulose fibers are affected by coating using the LbL method is to use spherical beads made from regenerated cellulose. In the present work, these beads were treated with polyallylamine hydrochloride (PAH) and hylauronic acid (HA) as well as with PAH and alginate (Alg) before being allowed to dry together and then subjected to tensile testing to clarify the adhesion between the surfaces. The beads were treated with five and ten bi-layers of these polymers, respectively, and then dried together on an AKD-coated surface, to avoid adhesion to the underlying surface, to examine the adhesion between the beads. The adhesion increased when treated with LbL and became higher upon adsorption of multiple layers of polyelectrolytes and the Alg / PAH system showed the greatest increase. Ten-layer samples of Alg / PAH were also tested after a solution of calcium chloride was added during drying, resulting in poorer adhesion between the beads. / Med klimatfrågans växande inverkan på både politiska beslut och hur företagen utvecklar sina produkter så läggs det allt större vikt vid att hitta miljövänliga alternativ till fossilbaserade material. Ett av de mer intressanta materialen är cellulosa vilket är världens mest naturligt förekommande polymer och som kan användas i en rad olika tillämpningar. Ett sätt att modifiera fibrerna och att ändra deras egenskaper är att använda sig av en metod som kalls Layer-by-layer (LbL) behandling där två polymerer mot motsatt laddning växelvis adsorberas till fiberytan. En annan möjlighet är att oxidera cellulosan i fibrerna så att de erhåller de en högre laddning. Detta innebär dels att fibrerna kan adsorbera en högre mängd katjoniska tillsatskemikalier samt att fibrerna sväller mera vilket innebär att de plasticeras och kan skapa starkare fogar mellan fiberytorna i torrt tillstånd vilket resulterar i starkare torra fibernätverk. Vedbaserade fibrer är dock små och inhomogena såväl kemiskt som morfologiskt vilket innebär att det är nödvändigt att använda modellsystem för att kunna klarlägga, i detalj, hur behandlade och icke behandlade ytor växelverkar med varandra på en molekylär nivå. Ett modellsystem som kan användas för att undersöka hur cellulosafibrer påverkas av att beläggas med hjälp av LbL metoden är att använda sig av sfäriska kulor tillverkade från regenererad cellulosa. I föreliggande arbete behandlades dessa kulor med polyallylaminhydroklorid (PAH) och hylauronsyra (HA) samt med PAH och alginat (Alg) innan de tilläts torka ihop och därefter utsattes för dragprovning för att klarlägga adhesionen mellan ytorna. Kulorna behandlades med fem respektive tio bilager av dessa polymerer och torkades sedan ihop på en AKD-belagd yta, för att undvika adhesion till den underliggande ytan, för att undersöka adhesionen mellan kulorna. Adhesionen ökade när de behandlades med LbL och blev högre vid adsorption av flera lager polyelektrolyter och systemet med Alg/PAH resulterade i den största ökningen. Prover med tio lager av Alg/PAH testades även efter att en lösning av kalciumklorid tillsattes under torkningen vilket resulterade i en sämre adhesion mellan kulorna.

Systemisch applizierte Therapeutika können erhebliche Nebenwirkungen auslösen, welche auf Grund eines unspezifischen Transports oder einer hohen Dosis von appliziertem Wirkstoff auftreten. Daher bedarf es der Entwicklung neuartiger Wirkstoff-Transportsysteme (Drug Delivery Systems) welche in der Lage sind, Wirkstoffe in genau definierbaren Dosen gezielt in die adressierte Zelle zu transportieren. Ein vielversprechender Ansatz, welcher diesen Anforderungen nachkommt, findet sich in der Layer-by-Layer-Technik (LbL), d.h. der wechselseitigen Assemblierung von Polymeren/Wirkstoffen auf soliden sphärischen Templaten, eines funktionellen Supported Lipid Bilayers sowie der Oberflächenfunktionalisierung mit spezifischen Antikörpern. Dabei ist die Homogenität und Regularität des Supported Lipid Bilayers von großer Bedeutung, um in biomedizinischen Anwendungen eine ungewollte Interaktion mit Serumkomponenten sowie eine Opsonierung zu verhindern. Insbesondere die funktionelle Lipidkomponente besitzt allerdings maßgebliche Auswirkungen auf diese Parameter. In dieser Arbeit wurde die Idee der Oberflächenfunktionalisierung von LbL-beschichteten Silica-Mikropartikeln (SiO2) mit einem funktionellen Supported Lipid Bilayer aufgegriffen und weiterentwickelt, wobei insbesondere die Homogenität des Supported Lipid Bilayers auch auf sehr kleinen Längenskalen (wenige Nanometer) bestimmt wurde. In einem letzten Schritt konnte anhand zweier verschiedener Zelllinien (3T3 und Vero) die Adaptivität und Effektivität des entwickelten Drug Delivery Systems nachgewiesen werden.

Materiais auto-organizados constituídos de V2O5 xerogel, poli(etilenoimina) (PEI) e nanopartículas de carbono (NpCs) foram obtidos por meio da técnica camada-por-camada (LbL). A metodologia aplicada permitiu a obtenção de filmes finos com elevado controle de espessura além de permitir um crescimento linear dos filmes, denominados neste trabalho V2O5/PEI e V2O5/PEI/NpCs. Além disso, o desempenho eletroquímico dos materiais auto-organizados foi comparado a um eletrodo de V2O5. Análises de FTIR mostraram que interações específicas entre os grupos amina do PEI e os grupos carboxila do V2O5 são responsáveis pelo crescimento do filme. Estas interações permitem a formação de um campo eletrostático capaz de blindar as interações entre os íons lítio e os oxigênios da vanadila (V=O) e, por consequência, são responsáveis pelo aumento na mobilidade iônica dos íons lítio no interior da matriz hospedeira e, portanto, um aumento na capacidade de armazenamento de carga. Resultados obtidos através de medidas de carga/descarga mostram que o V2O5/PEI/NpCs apresenta uma melhor desempenho do que os demais materiais estudados neste trabalho. Estes resultados mostram que a capacidade específica do V2O5/PEI/NpCs foi de 137 mA h g-1 para a menor densidade de corrente aplicada e aproximadamente 1,6 vezes maior do que os valores de capacidade específica para os outros materiais para a maior densidade de corrente aplicada. Além disso, estas medidas permitiram a observação de uma menor variação na razão estequiométrica máxima (xmáx) em função das densidades de corrente aplicadas para os filmes auto-organizados, fato este relacionado a uma maior mobilidade iônica dos íons lítio no interior dessas matrizes. Os resultados obtidos a partir de espectroscopia de impedância eletroquímica (EIS) mostraram que a difusão dos íons lítio no interior das matrizes auto-organizadas é maior do que no caso do V2O5, cujos valores do coeficiente de difusão foram de 1,64 x 10-15, 1,21 x 10-14 e 2,26 x 10-14 cm2 s-1 para os filmes V2O5, V2O5/PEI e V2O5/PEI/NpCs, respectivamente. Sendo assim, o polímero e as NpCs promoveram novos caminhos condutores e permitiram a conexão elétrica entre camadas isoladas da matriz V2O5. Dessa forma, novos nanocompósitos foram obtidos visando demonstrar o método de auto-organização empregado para melhorar o transporte de carga em matrizes hospedeiras. / Self-assembled materials constituted of V2O5 xerogel, poly (ethyleneimine) (PEI), and carbon nanoparticles (CNPs) were obtained by the layer-by-layer (LbL) technique. The applied methodology permitted the obtainment of thin films with high thickness control and also permitted a linear growth of the films, which will be named V2O5/PEI and V2O5/PEI/CNPs. Besides, the electrochemical performance of the self-assembled materials was compared to a V2O5 electrode. FTIR analyses showed that the specific interactions between the amine groups of PEI and the vanadyl groups of the V2O5 are responsible for the film growth. These interactions permitted the formation of an electrostatic shield capable of hindering the interactions between the lithium ions and the vanadyl oxygen atoms (V=O) and are consequently responsible for the enhancement on the ionic mobility of the lithium ions within the host matrix, leading to a higher energy storage capability. Results obtained by the charge/discharge measurements showed that V2O5/PEI/CNPs presents a better performance than the other materials studied for this research. These results demonstrated that the specific capacity of the V2O5/PEI/CNPs was 137 mA h g-1 under the lowest current density applied and approximately 1.6 times higher than the specific capacity values obtained for the other materials under the highest current density applied. Moreover, it was observed that the variation of the maximum stoichiometric ratio (xmax) as a function of the current density is lower for the self-assembled materials than for the V2O5 electrode, which can be related to the higher ionic mobility of the lithium ion within the self-assembled materials. Electrochemical Impedance Spectroscopy (EIS) data demonstrated that the diffusion of the lithium ions within the self-assembled materials is higher than within the V2O5 electrode, and the diffusion coefficients were 1.64 x 10-15, 1.21 x 10-14 e 2.26 x 10-14 cm2 s-1 for V2O5, V2O5/PEI and V2O5/PEI/CNPs, respectively. Thus, the polymer and the CNPs provided new conducting pathways and connected isolated V2O5 chains in the host matrix. Therefore, novel spontaneous nanocomposites were formed, aiming to demonstrate the self-assembled method adopted for improving charge transport within host matrices.

Polyelektrolytmikrokapseln (PEMC) stellen ein neuartiges System künstlicher Zellen dar. Durch Einbringen von z.B. Hämoglobin in solche PEMC können sie als  künstliche Erythrozyten den Gastransport im Organismus unterstützen bzw. übernehmen. Es muss jedoch berücksichtigt werden, dass jede Zelle des Säugtierorganismus zur Aufrechterhaltung ihrer Funktion Enzyme benötigt, die ihre Stoffwechselfunktionen katalysieren. Um sich der Lösung dieses Problems bei der Entwicklung eines künstlichen Erythrozyten schrittweise zu nähern, wurde als Modellenzym Trypsin ausgewählt. Es wurden Polyelektrolytmikrokapseln (PEMC) auf der Basis von Erythrozyten durch Selbstassemblierung von Polynatriumstyrensuphonat (PSS) und Polyallylamino-hydrochlorid (PAH) hergestellt ((PSS/PAH)2PSS), und anschliessend nach der Layer-by-Layer Methode (LbL) alternierend mit Trypsin und den Polyelektrolyten (PE) PSS, Alginat oder Dextransulphat weiterbeschichtet. Der Schichtenaufbau wurde durch Zellelektrophorese, konfokale Laserscanning-mikroskopie (CLSM), Durchflusszytometrie (FACS) und photometrische Proteinbestimmung charakterisiert und quantifiziert. Die Aktivität des an der PEMC-Membran immobilisierten Enzyms wurde untersucht und mit der Aktivität freien Trypsins verglichen. Weiterhin wurden pH-Profile von freiem Enzym mit denen des immobilisierten Trypsins verglichen. Der Schichtaufbau aus Trypsin und den unterschiedlichen Polyelektrolyten wurde anhand der Änderung der elektrophoretischen Mobilität beim Aufbringen jeder Schicht, sowie durch die Zunahme der photometrisch bestimmten Proteinmenge pro PEMC charakterisiert. Außerdem wurde Trypsin mit Fluoreszeinisothiozyanat (FITC) markiert und in den Beschichtungsserien die Zunahme der flowzytometrisch bestimmten Fluoreszenz-Intensität mit jeder aufgebrachten FITC-Trypsin Schicht beobachtet. Die Aktivität des an den PEMC immobilisierten Trypsins beträgt etwa 30% der Aktivität freien Trypsins gleicher Konzentration. Es konnte gezeigt werden, dass sich Trypsin im Rahmen eines Schichtaufbaus nach der LbL-Technologie in die Membran der verwendeten PEMC einbringen lässt. Dabei behält das Enzym einen Teil seiner Funktion. / Artificial cells are not only used to study the biological processes of living cells, they also serve as micro reactors to provide certain functions in the organism. Polyelectrolyte microcapsules (PEMC) represent a new approach to artificial cell studies. When filled with hemoglobin, PEMC are able to perform the erythrocyte gas exchange. This work shows the general possibility of integrating enzymes into the PEMC membrane. PEMC were composed using the layer-by-layer (l-b-l) technique. Glutaraldehyde stabilized human red blood cells (RBC) served as templates and were coated with five layers poly(styrene sulfonate) (PSS) and poly(allylaminehydrochloride) (PAH). After decomposition of the RBC by sodium hypochlorite, the PEMC were coated with ten layer pairs of trypsin and either PSS or alginate. The trypsin layer growth was followed performing measurements by cell electrophoresis, confocal laser scanning microscopy (CLSM), flow cytometry (FACS) and protein determination according to Lowry after each adsorption step. Results showed a continuous layer buildup for both polyelectrolytes and no desorption of trypsin. The amount of immobilized enzyme was larger for the coating series with trypsin/PSS compared to that with trypsin/alginat. This was concluded as a result of PSS/trypsin complex formation. Normalizing the enzym activity to the amount of adsorbed trypsin no significant differences between the activity of PSS-PEMC and alginate-PEMC were found. Further experiments prove that PSS inhibits the enzyme activity and alginat does not.

Made available in DSpace on 2017-07-24T19:37:59Z (GMT). No. of bitstreams: 1 ClicianeGuadalupeJesus.pdf: 2429700 bytes, checksum: c3ac935bcc2b97480f80dc8cf9ff472d (MD5) Previous issue date: 2009-02-27 / Nanostructured films composed by a 3-n-propylpyridinum silsesquioxane polymer (designated as SiPy+Cl-) and copper (II) tetrasulphophthalocyanine (CuTsPc) were produced using the Layer-by-Layer technique (LbL). The deposition of the bilayers was monitored by UV-Vis spectroscopy accompanying the absorbance of Q-band at 617 nm. It was observed that the absorbance linearly increased with the number of SiPy+Cl-/CuTsPc or CuTsPc/SiPy+Cl- bilayers, indicating that the same amount of material was deposited at each step of film formation. FTIR spectra showed that there is a specific interaction by the SO3 - groups of CuTsPc and the pyridinium groups of the polycation, SiPy+Cl-. Morphological studies of films surfaces showed that their roughness and thickness increase with the number of bilayers. The films were employed to detect dopamine (DA) and ascorbic acid (AA) using cyclic voltammetry. It was observed that the number and the sequence of bilayers deposition directly influenced on the electrochemical response in presence of the analytes. LbL films with lower number of bilayers (1 to 5 bilayers) presented higher current values in presence of the analytes, which is attributed to the higher facility of diffusion of target species to the electrode surface and enhancement of the efficiency of the electron transfer process. Considering the sequence of bilayers deposition, it was observed that the CuTsPc/SiPy+Cl- film did not show any redox peaks in the potential range -0.2 V to 1.6 V vs Ag/AgCl in presence of DA and AA. In contrast, the SiPy+Cl-/CuTsPc LbL film, presented a defined oxidation redox peak at approximately 1.2 V for DA and 0.8 V for AA, which linearly increased with DA concentration in HCl 1.0x10-3 molL-1 electrolyte solution (pH 3). Studies in different scan rates for the SiPy+Cl-/CuTsPc LbL film in presence of these analytes showed that the anodic peak current (Ipa) linearly increased with the square root of the scan rate (n1/2 ) which is a typical behavior for systems governed by a diffusion controlled mechanism. The relationship Ipa/ n1/2 vs n resulted in an exponential profile, confirming the existence of an electrocatalytical process for both AA and DA provided by CuTsPc in the LbL film. Using differential pulse technique, films comprising SiPy+/CuTsPc were able to distinguish between DA and ascorbic acid (AA), with a potential difference of approximately with 400 mV, in the concentration range of 9.0x10-5 to 2.0x10-4 molL- 1(in pH 3.0) and detection limits in the order of 10-5 molL-1. / Filmes nanoestruturados formados entre o polímero 3-n-propilpiridínio silsesquioxano (designado como SiPy+Cl-) e ftalocianina tetrasulfonada de cobre (II) (CuTsPc) foram produzidos usando a técnica Layer-by-Layer (LbL). A formação dos filmes foi monitorada por espectroscopia na região do UV-Vis, acompanhando-se a absorbância da banda Q da ftalocianina em 617 nm. Observou-se que a absorbância aumentou linearmente com o número de bicamadas para os filmes SiPy+Cl-/CuTsPc ou CuTsPc/SiPy+Cl-, indicando que a mesma quantidade de material foi depositado a cada bicamada depositada. Espectros FTIR mostraram que há interação específica entre os grupos SO3 - da CuTsPc e o anel piridínio do policátion, SiPy+Cl-. Estudos da morfologia da superfície dos filmes mostraram que a rugosidade média e espessura dos filmes aumentam de acordo com o número de bicamadas. Os filmes foram empregados para detectar DA e AA, utilizando-se a técnica de voltametria cíclica. Observou-se que o número de bicamadas e a seqüência de deposição das mesmas influenciam diretamente sobre a resposta eletroquímica na presença dos analitos. Filmes LbL com menor número de bicamadas (1 a 5 bicamadas) apresentaram maiores valores de corrente, fato este atribuído a maior facilidade de difusão das espécies à superfície do eletrodo, aumentando a eficiência do processo de transferência de elétrons. Com relação à sequência de deposição das bicamadas constatou-se que o filme CuTsPc/SiPy+Cl- não mostrou picos redox na faixa de potencial de -0,2 V a 1,6 V vs Ag/AgCl na presença de DA e AA. Enquanto que o filme SiPy+Cl-/CuTsPc, apresentou um pico de oxidação bem definido em aproximadamente 1,2 V, para DA e em 0,8 V para AA, o qual aumentou linearmente com a concentração dos analitos utilizando HCl como eletrólito suporte. Estudos em diferentes velocidades de varredura do eletrodo SiPy+Cl-/CuTsPc na presença dos analitos mostraram que a corrente de pico anódica (Ipa) aumenta linearmente com a raiz quadrada da velocidade de varredura (n1/2), indicando que o processo de transferência de elétrons é controlado pela difusão das espécies à superfície do eletrodo. A relação entre Ipa/n1/2 vs n, resultou numa curva exponencial, confirmando a existência do processo eletrocatalítico resultante da oxidação da DA e AA proporcionada pela CuTsPc. Utilizando-se a técnica de voltametria de pulso diferencial, o eletrodo SiPy+Cl-/CuTsPc foi capaz de distinguir AA e DA quando presentes numa mesma solução, com um diferença de potencial de aproximadamente 400 mV, no intervalo de concentração de 9,0x10-5 a 2,0x10-4 molL-1(em pH 3) e limites de detecção (LOD) da ordem de 10-5 molL-1.

Des films multicouches à base de nanoparticules de TiO2 et d’Ag ont été construits sur des substrats modèles et des textiles via la technique du Layer-by-Layer (LbL). Les films à base de nanoparticules de TiO2 construits sur substrats modèles ont montré un comportement photocatalytique non conventionnel pour la minéralisation de l’acide formique en phase gaz sous irradiation UV-A, et une minéralisation très importante a été obtenue avec un film possédant une unique couche de nanoparticule de TiO2. Ces films ont également montré des propriétés biocides sous irradiation UV-A. La mise en œuvre d’une méthode one-pot, combinant la synthèse photo-induite des nanoparticules d’Ag et dépôt de la couche de TiO2 par LbL, a permis la synthèse de nanoparticules d’Ag directement au sein des films et une exaltation très importante des propriétés photocatalytiques des films. Les méthodes de constructions ont été transférées avec succès sur textiles. Les films restent photocatalytiquement actifs et biocides sous irradiation UV-A après plusieurs cycles de lavages. / TiO2 and Ag nanoparticle multilayered films were constructed on model substrates and textiles via Layer-by-Layer (LbL) assembly. The TiO2 nanoparticle based films constructed on model substrates showed a non-conventional photocatalytic behaviour for gas phase formic acid mineralisation upon UV-A irradiation, and a high mineralisation was obtained for a single layer TiO2 nanoparticle film. These films also showed biocidal properties upon UV-A irradiation. The elaboration of a one-pot method, combining the photo-induced synthesis of Ag nanoparticles and the LbL deposition of TiO2 nanoparticle layer, allowed the direct synthesis of Ag nanoparticles within the films and a high enhancement of the film photocatalytic properties. The construction methods were successfully transfered on textile surfaces. The films were photocatalytically active and biocidal under UV-A irradiation after several washing treatment cycles.

A celulose é o principal polímero derivado de fonte renovável de uso industrial tanto em termos de volume como em número de aplicações. A celulose é comercializada na forma de polpa, que se trata de uma commodity cuja principal aplicação é a indústria de papel e de derivados de celulose, tais como os seus éteres e ésteres. Com o advento das nanoceluloses, que podem ser obtidas diretamente da polpa química, se observa um expressivo aumento no interesse por esses materiais. A modificação superficial tanto das fibras (polpa) como das microfibrilas é de grande interesse, pois podem permitir a ampliação do uso desses materiais uma vez que suas propriedades poderiam ser modificadas. O desenvolvimento de métodos de modificação em meio aquoso da celulose em suspensão é de grande interesse em especial se realizado com o uso de agentes sustentáveis em contexto de química verde. Este trabalho visou a modificação da polpa de celulose por duas vias: química e física, realizadas inteiramente em meio aquoso e utilizando materiais de caráter renováveis. A modificação física da fibra de celulose \"never-dried\" foi feita pelo método de auto-montagem (Layer-by-Layer) com o par de polieletrólito quitosana / carboximetilcelulose (CH / CMC) em meio aquoso. Fibras modificadas foram submetidas à analise morfológica (MEV e microscopia confocal no método de absorção de dois fótons e EDS), propriedade mecânica (módulo elástico e limite de resistência à tração) e potencial zeta. O complexo CH / CMC depositado sobre as fibras apresentou uma espessura de aproximadamente 50 nm por camada e um aumento de aproximadamente 170% no limite de resistência a tração das folhas produzidos a partir das fibras, demonstrando uma forte interação fibra/polieletrólitos. Através da técnica de absorção de dois fótons foi possível identificar a deposição das camadas fora e dentro das fibras sem o uso de cromóforo. A modificação química da nanofibra de celulose foi feita pela enxertia de grupamentos furânicos na superfície da fibra, oxidada. Em seguida de uma reação com uma bismaleimida através da reação de \"click\" de Diels-Alder em meio aquoso. Os géis foram caracterizados por meio da técnica de calorimetria diferencial de varredura (DSC) e viscosimetria, com os quais pode-se verificar o efeito da termorreversibilidade uma vez que a 65°C ocorre gelificação do sistema e 95°C ocorre reversão do gel como resultado das reações DA e retro Diels-Alder. As modificações das fibras e nanofibras de celulose em meio aquoso foram bem-sucedidas, o que pode impulsionar o uso da polpa de celulose em novas aplicações originais como artefatos de papel fortes e géis biocompatíveis, visando a estratégia green chemistry. / Cellulose is the main polymer derived from renewable sources of industrial use, in terms of volume and number of applications. Cellulose is marketed in the pulp form, which is a commodity whose main application is the paper industry and derived from pulp, such as its ethers and esters. The advent of nanocelluloses, which can be obtained directly from the chemical pulp, there is an expressive increase in these materials. The superficial modification in fibers (pulp) and microfibrils is great interest, since they can allow the amplification of the use of these materials since their properties could be modified. The development of methods for modification of cellulose in aqueous suspension is of particular interest especially if carried out with sustainable agents in the context of green chemistry. This work aimed at the modification of the cellulose pulp by two routes: chemistry and physics, performed entirely in aqueous medium and using renewable character materials. The physical modification of the \"never-dried\" cellulose fiber was done by the self-assembly method (Layer-by-Layer) with the polyelectrolyte pair chitosan / carboxymethylcellulose (CH / CMC) in aqueous medium. Modified fibers were subjected to morphological analysis (SEM and confocal microscopy in two-photon absorption technique and EDS), mechanical properties (elastic modulus and tensile strength) and zeta potential. The CH / CMC complex deposited under the fibers had a thickness of approximately 50 nm per layer and an increase of approximately 170% in the tensile strength of the sheets in compare of unmodified fibers sheets, showing a strong interaction between fiber and polyelectrolyte. Through the technique of two-photon adsorption, it was possible to identify the layers deposition outside and inside the fibers without the use of chromophore. The chemical modification of the cellulose nanofiber was made by the grafting of furanic groups on the surface of the oxidized fiber. Following by reaction with a bismaleimide through the \"click\" reaction of Diels-Alder in aqueous medium. The thermoreversible hydrogels were characterized by differential scanning calorimetry (DSC) and viscosimetry, which the effect of thermoreversibility can be verified at 65 °C when the gelation of the system occurs and 95 °C gel reversion occurs because of DA and retro Diels-Alder reactions. Modifications of cellulose fibers and nanofibers in aqueous media have been successful, which may increase the use of cellulose pulp in novel applications such as strong paper artifacts and biocompatible gels, targeting the green chemistry strategy.