La cellulose bactérienne (CB) est bien connue pour sa biocompatibilité, moulabilité, pureté et cristallinité ainsi que pour sa structure fibrilleuse nanométrique. Cependant, la production des matériaux par des microorganismes est innovante. La présente thèse initialise ce type de bioproduction dans nos laboratoires. Les bactéries productives de cellulose sont isolées à partir d'un vinaigre Libanais. Plusieurs études cinétiques sont établies. Les isolats sont étudiés dans différents milieux de cultures en variant la source de carbone et la température d'incubation, pour déterminer les conditions optimales recommandées pour la production de meilleurs rendements de CB. La bactérie productive de CB a été étudiée en détails au niveau de son cycle de vie et phases de croissance. La physiologie des cellules a été clarifiée et les mécanismes qui précédent et qui accompagnent la synthèse de CB ont été expliqués. Un modèle mathématique se basant sur l'équation logistique est employé pour standardiser les paramètres étudiés. Le rendement de CB a été accru en appliquant différents chocs aux cellules. Le choc thermique appliqué pendant les étapes précoces d'incubation ainsi que le choc acide ont montré des résultats innovants et accéléré le métabolisme de synthèse de CB. L'aspect environnemental du travail a été valorisé en préparant un milieu de culture extraits des fruits et légumes endommagés. En termes d'application, la CB a été utilisée pour produire des papiers et des papiers résistants à l'eau et comme additive dans un prototype d'industrie de papier. Ainsi des composites de cellulose/Liquides ioniques ont été produits afin de performer des matériaux à haute constante diélectriques / Bacterial cellulose (BC) is a wellknown polymer of this family. Its main attractive properties are the biocompatibility, moldability, purity, crystallinity and fibrillar structure at the nanoscaled level. The production of such materials by microorganisms is an innovative procedure. In order to trigger this production procedure in our laboratories, the present thesis was the preliminary step to go through this huge micro-world. In the first step, we isolated cellulose producers from Lebanese vinegar. Kinetic studies were established to clarify the profile of the producer and to optimize cellulose production. The isolates were studied under different incubation temperatures in different microbiological media and at different carbon sources levels to determine optimal conditions for BC production. In the second step, cellulose producer was studied concerning bacterial phases and life cycles. Cells physiologies were clarified and mechanisms that accompany cellulose formation on the top of cultures were discussed. A mathematical model was set basing on Logistic equation to standardize the parameters. Then, cellulose yield was enhanced by different cells choc methods. Thermal choc was applied on cultures during earlier stages of incubation. Moreover, acids were used as doping agents to the culture media. In parallel, to satisfy the eco-friendly aspect of the work, bacterial cellulose production was optimized using fruits and vegetables wastes juice. Papers and waterproof papers were produced using BC. BC was also used as an additive in industrial paper making and was found to enhance mechanical resistance of the papers. In addition, a high-K material was performed using bacterial cellulose and ionic liquids

O lactato é um metabólito chave formado pelo metabolismo anaeróbico da glicose nos músculos, e tem se tornado um biomarcador importante no âmbito clínico e esportivo. Atualmente, existem biossensores eletroquímicos portáteis que são capazes de determinar os níveis de lactato no organismo em tempo real. No entanto, tal método é invasivo uma vez que requer amostras de sangue. O presente projeto tem como objetivo desenvolver um biossensor eletroquímico descartável para detecção de lactato no suor. Para isto a configuração do dispositivo foi feita utilizando a celulose bacteriana como substrato para obtenção de um dispositivo que seja resistente à deformação mecânica, especialmente quando molhado e, também, permeável ao suor. A impressão dos eletrodos de carbono neste substrato foi efetuada utilizando o processo de serigrafia. Com os dispositivos produzidos foram realizados experimentos de voltametria cíclica e espectroscopia de impedância eletroquímica, a fim de caracterizar o sensor desenvolvido e investigar a influência do pré-tratamento eletroquímico na sua performance analítica. A partir da modificação da superfície eletródica com nanocubos de Azul da Prússia foi possível desenvolver um sensor eletroquímico para detecção de peróxido de hidrogênio. A cronoamperometria foi utilizada para a determinação da curva analítica para o peróxido de hidrogênio. Com todos os parâmetros da cronoamperometria otimizados, uma dependência linear da corrente catódica com a concentração de peróxido de hidrogênio foi obtida, com a equação: Ip = 0,1 + 4,30 [H2O2], com r2 = 0,999 (n = 3). Esta curva analítica mostrou que a metodologia apresenta um Limite de Detecção e de Quantificação de mol L-1 e mol L-1, respectivamente. Para a configuração do biossensor eletroquímico a enzima lactato oxidase foi incorporada à superfície do papel pelo método de ligação covalente. Adotando esta metodologia foi verificado um aumento da área eletroativa que possibilitou uma melhora significativa no desempenho do sensor desenvolvido. No qual se obteve uma região linear de 1-24,0 mmol L-1 em suor sintético, obtendo-se Limites de detecção e Quantificação de e mol L-1. Tais parâmetros se mostraram adequados já que o suor pode apresentar níveis de aproximadamente 25 mmol L-1 de lactato. De modo geral, foi possível desenvolver uma plataforma eletroquímica no substrato de celulose bacteriana para a detecção de lactato em amostras de suor sintético. O dispositivo desenvolvido apresentou uma boa durabilidade e resistência ao se executarem sucessivas medidas corroborando a viabilidade deste substrato na projeção de sensores vestíveis para a aplicação direta na pele e monitoramento dos níveis de lactato em tempo real. / Lactate is a key metabolite formed in the anaerobic metabolism of glucose in the muscles. It has become an important biomarker in the clinical and sport scopes. Currently, there are portable biosensors that are able to determine lactate levels in real time. However, these methods are invasive since they require blood samples. Herein, we aim to develop a disposable wearable electrochemical biosensor for detection of lactate in sweat. For this purpose the configuration of the device was made with bacterial cellulose substrate in order to be permeable to sweat and resistant to mechanical deformation, especially when wet. The fabrication of the electrodes was made through screen printing technique. Electrochemical impedance spectroscopy and cyclic voltammetry were used to characterize the sensor developed in order to investigate the influence of the electrochemical pre-treatment in the analytical performance of the electrodes. To develop an electrochemical sensor for the detection of hydrogen peroxide the screen printed electrode was modified with Prussian blue nanocubes. Chronoamperometry experiments were used to detect of hydrogen peroxide. From optimized chronoamperometry parameters, a linear dependence of the cathodic current with the hydrogen peroxide concentration was obtained with the equation: Ip = 0.1 + 4.30 [H2O2], with r2 = 0.999 (n = 3). The limit of detection (LOD) and the limit of quantification (LOQ) were mol L-1 e mol L-1, respectively. For the configuration of the electrochemical biosensor the lactate oxidase enzyme was immobilized on the paper surface by the covalent bonding method. Adopting this methodology was verified an increase of the electroactive area that allowed a significant improvement in the performance of the developed sensor. In which a linear concentration range of 1-24.0 mmol L-1 was obtained in the synthetic sweat, obtaining LOD and LOQ of mol L-1 e mol L-1, respectively. Such parameters were adequate since sweat may have lactate levels of approximately 25 mmol L-1. Finally, it was possible to develop an electrochemical platform using the bacterial cellulose substrate for the detection of lactate in samples of synthetic sweat. The developed device presented a good durability and resistance when performing electrochemical measurements assuring the feasibility of this substrate in the projection of wearable sensors for the direct application to skin and monitoring of lactate levels in real time.

Denna kandidatuppsats undersöker framtagningen av ett bakteriellt cellulosamaterial (BC-material), samt undersöker om materialets vattenavvisande egenskaper kan förbättras för att kunna möjliggöra användning som textilt material. Arbetet grundar sig i det faktum att BC- materialet är av en hydrofil karaktär, något som den brittiska designern Suzanne Lee utryckt vara ett problem för dess användningsmöjligheter. Arbetet behandlar en litteraturstudie av BC, vilken ligger till grund för en experimentel del där odling, vattenavvisande beredningar och vattenavvisande tester utförts. Gällande BC-produktion och materialframtagning har faktorer som pH-värde, temperaturförhållanden, och recept visat sig påverka cellulosaproduktionen. Ett varmare temperaturförhållande på 30°C jämfört med rumstemperatur (20- 22°C) har uppvisat bättre cellulosatillväxt. Detsamma gäller även för användandet av äppelcidervinäger i odlingmediumet, vilket uppvisat positiva resultat. Testerna av det framtagna BC-membranet har för det första kunnat bekräfta dess påstådda hydrofilitet. Vidare har även de vattenavvisande behandlingarna visat positiva resultat, även om användarmöjligheterna för materialet fortfarande anses vara begränsade inom det textila området. En ökning av kontaktvinkeln från 40,76° till 96,98° uppvisades efter att en behandling med en syntetisk vaxpolymer applicerats. Denna ökning på drygt 100 % skapade en kontaktvinkel över 90°, vilket teoretiskt betyder att materialets karaktär gått från hydrofilt till hydrofobt. Ett likvärdigt resultat uppvisades även efter en behandling med en vaxdendrimer. Materialet uppvisade dock tydliga resultat på att absorbera vatten vid längre tid av blötläggning, oavsett om det behandlats eller ej. / This bachelor thesis is investigating the development of a material based on bacterial cellulose (BC), as well as examine and test the material's hydrophobic properties. This is made in order to improve its user possibilities as a textile material. The motive is based on the fact that BC- materials have a hydrophilic nature, something that the British designer Suzanne Lee expressed as a problem for its user possibilities. The thesis process a literature study of BC, which is used for an experimental study where cultivation, water repellent treatments and water repellent tests are performed. Regarding BC-production and material creation, factors as pH-levels, temperature conditions and the recipes has shown to affect the cellulose production. The cellulose levels occurred to increase during a warmer condition at 30 °C compared to room temperature (20-22°C), both conditions where used for the cultivation. The same positive results also occurred when apple cider vinegar was used in the cultivation bath. The tests on the developed BC-membrane, initially confirmed its alleged hydrophilic nature. Furthermore, positive results occurred for the water repellant-treated materials, even if the user possibilities still is considered to be limited in the textile field. The contact angle increased from 40.76 ° to 96.98 ° on the material treated with a synthetic wax polymer, which results in a 100% increase. The angle of 90°, theoretically means that the character of the material changed from hydrophilic to hydrophobic. Similar results also occurred after treatment with a wax dendrimer. The material, however, showed significant results in absorbing water when subjected for a longer time of soaking, whether it was treated or not.

Cellulose nanofibrils (CNFs) are nanoscale fibers of high aspect ratio that can be isolated from a wide variety of cellulosic sources, including wood and bacterial cellulose. With high strength despite of their low density, CNFs are a promising renewable building block for the preparation of nanostructured materials and composites. To fabricate CNF-based materials with improved inherent rheological and mechanical properties and additional new functionalities, it is essential to tailor the surface properties of individual CNFs. The surface structures control the interactions between CNFs and ultimately dictate the structure and macroscale properties of the bulk material. In this thesis we have demonstrated different approaches, ranging from non-covalent adsorption and covalent chemical modification to modification of cellulose biosynthesis, to tailor the structure and surface functionalities of CNFs for the fabrication of advanced materials. These materials possess enhanced properties such as water-redispersibility, water absorbency, dye adsorption capacity, antibacterial activity, and mechanical properties. In Paper I, CNFs were modified via the irreversible adsorption of carboxymethyl cellulose (CMC). The adsorption of small amounts of CMC onto the surface of CNFs prevented agglomeration and co-crystallization of the nanofibrils upon drying, and allowed the recovery of rheological and mechanical properties after redispersion of dried CNF samples. In Paper II, CNFs bearing permanent cationic charges were prepared through quaternization of wood pulp fibers followed by mechanical disintegration. The activation of the hydroxyl groups on pulp fibers by alkaline treatment was optimized prior to quaternization. This optimization resulted in individual CNFs with uniform width and tunable cationic charge densities. These cationic CNFs demonstrated ultrahigh water absorbency and high adsorption capacity for anionic dyes. In Paper III, via a similar approach as in Paper II, CNFs bearing polyethylene glycol (PEG) were prepared by covalently grafting PEG to carboxylated pulp fibers prior to mechanical disintegration. CNFs with a high surface chain density of PEG and a uniform width were oriented to produce macroscopic ribbons simply by mechanical stretching of the CNF hydrogel network before drying. The uniform grafted thin monolayer of PEG on the surface of individual CNFs prevented the agglomeration of CNFs and facilitated their alignment upon mechanical stretching, thus resulted in ribbons with ultrahigh tensile strength and modulus. These optically transparent ribbons also demonstrated interesting biaxial light scattering behavior. In Paper IV, bacterial cellulose (BC) was modified by the addition of chitin nanocrystals (ChNCs) into the growing culture medium of the bacteria Acetobacter aceti which secretes cellulose in the form of entangled nanofibers. This led to the in situ incorporation of ChNCs into the BC nanofibers network and resulted in BC/ChNC nanocomposites exhibiting bactericidal activity. Further, blending of BC nanofibers with ChNCs produced nanocomposite films with relatively lower tensile strength and modulus compared to the in situ cultivated ones. The bactericidal activity increased significantly with increasing amount of ChNCs for nanocomposites prepared by direct mixing of BC nanofibers and ChNCs. In Paper V, CNFs were isolated from suspension-cultured wild-type (WT) and cellulose-binding module (CBM) transformed tobacco BY-2 (Nicotiana tabacum L. cv bright yellow) cells. Results from strong sulfuric acid hydrolysis indicated that CNFs from transgenic cells overexpressing CBM consisted of longer cellulose nanocrystals compared to CNFs from WT cells. Nanopapers prepared from CNFs of transgenic cells demonstrated significantly enhanced toughness compared to CNFs of WT cells. / <p>QC 20141103</p> / CARBOMAT

Submitted by Thais Silva do Amaral null (thais_rpss@yahoo.com) on 2016-06-03T19:14:32Z No. of bitstreams: 1 Thais Silva do Amaral-Dissertação.pdf: 3804617 bytes, checksum: 8083e47078da73695bac6f8aa62e3778 (MD5) / Approved for entry into archive by Ana Paula Grisoto (grisotoana@reitoria.unesp.br) on 2016-06-08T13:24:26Z (GMT) No. of bitstreams: 1 amaral_ts_me_araiq_par.pdf: 1221750 bytes, checksum: e72ea0e2cee4ebb7654b4a0d18d9289f (MD5) / Made available in DSpace on 2016-06-08T13:24:26Z (GMT). No. of bitstreams: 1 amaral_ts_me_araiq_par.pdf: 1221750 bytes, checksum: e72ea0e2cee4ebb7654b4a0d18d9289f (MD5) Previous issue date: 2015-05-12 / Polímeros derivados do petróleo como polietileno tereftalato (PET) e polietileno naftalato (PEN), são utilizados em larga escala como substratos em diversos dispositivos eletrônicos. A crescente preocupação com o meio ambiente nos leva a buscar alternativas sustentáveis na utilização de materiais para fabricação de novas tecnologias. Neste trabalho, com o intuito de avaliar a viabilidade da substituição destes substratos por polímeros naturais, foi explorada uma biocelulose, a celulose bacteriana (CB), secretada por bactérias Acetobacter xylinum, que é um polímero de obtenção ―verde‖, não gerando resíduos ou altos impactos ambientais para ser produzida, além de possuir características desejáveis para ser utilizado como substrato em novos materiais, como resistência mecânica com módulo de Young de 134 GPa, tamanho nanométrico das fibras e transparência. Membranas funcionais foram obtidas pelo crescimento de nanofios de óxido de zinco na sua superfície. Os nanofios de ZnO foram obtidos com comprimento médio de 1,69 ± 0,08 μm e diâmetro de 37,2 ± 4,2 nm. Os materiais foram avaliados estruturalmente pela Difratometria de Raios-x (DRX) e Microscopia Eletrônica de Transmissão de Alta Resolução (HRTEM), e quimicamente utilizando Espectroscopia de Espalhamento Raman e Espectroscopia Vibracional na Região do Infravermelho (FT-IR). Também foram realizadas de medidas de Impedância Elétrica e Análise termogravimétrica (TG/DTG). Por fim os materiais foram testados em três diferentes aplicações: como membrana para fotodegradação de corantes, sensor piezoelétrico e substrato removível para obtenção de fios de ZnO não suportados que se mostraram aplicações viáveis para o material. / Petroleum-derived polymers such as Polyethylene Terephthalate (PET) and Polyethylene Naphthalate (PEN), are largely used as substrates in various electronic devices. The growing concern with the environment leads us to seek sustainable alternatives in the use of materials for the manufacture of new technologies. In this work, in order to assess the feasibility of replacing these substrates by natural polymers, bacterial cellulose (BC) was explored, secreted by bacteria Acetobacter xylinum is a ―green‖ polymer that don’t generate waste or high environmental impacts to be produced, and has desirable characteristics for use as new substrate materials, such as mechanical strength with Young's modulus of 134 Gpa, nano-sized fibers and transparency. Functional membranes were prepared by growing ZnO nanowires on the BC dried membranes surface. The obtained ZnO nanowires presented an average length of 1.69 ± 0.08 m and diameter of 37.2 ± 4.2 nm. Materials were evaluated structurally by X-ray Diffraction (XRD) and High-resolution Transmission Electron Microscopy (HRTEM), chemically using Raman Scattering spectroscopy and Vibrational Spectroscopy in the Infrared Region (FT-IR). Electrical Impedance measurements and thermal gravimetric analysis (TG / DTG) were performed as well. Finally the materials were tested in three different applications: as a membrane for dyes photodegradation, piezoelectric sensor and removable substrate for obtaining unsupported ZnO nanowires that are viable applications for the material.

Made available in DSpace on 2014-12-17T14:13:37Z (GMT). No. of bitstreams: 1 NaisandraBS_TESE_1-50.pdf: 2251709 bytes, checksum: f894b2d51f4f9a6c372cbd1e00aa233d (MD5) Previous issue date: 2010-06-07 / Conselho Nacional de Desenvolvimento Cient?fico e Tecnol?gico / Bacterial cellulose (BC) has a wide range of potential applications, namely as temporary substitute skin in the treatment of skin wounds, such as burns, ulcers and grafts. Surface properties determine the functional response of cells, an important factor for the successful development of biomaterials. This work evaluates the influence of bacterial cellulose surface treatment by plasma (BCP) on the cellular behavior and its genotoxicity potential. The modified surface was produced by plasma discharge in N2 and O2 atmosphere, and the roughness produced by ion bombardment characterized by scanning electron microscopy (SEM) and atomic force microscopy (AFM). Cell adhesion, viability and proliferation on BCP were analysed using crystal violet staining and the 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyl-tetrazolium (MTT) method. Genotoxicity was evaluated using the comet and cytokinesis block micronucleus assay. The results show that the plasma treatment changed surface roughness, producing an ideal cell attachment, evidenced by more elongated cell morphology and improved proliferation. The excellent biocompatibility of BCP was confirmed by genotoxicity tests, which showed no significant DNA damage. The BCP has therefore great potential as a new artificial implant / A celulose bacteriana (CB) ? utilizada, geralmente como uma membrana tempor?ria, na substitui??o de pele lesionada, em feridas, queimaduras, ulcera??es ou como enxerto. Modifica??es em sua superf?cie podem determinar respostas no funcionamento celular dos tecidos adjacentes, influenciando sua biocompatibilidade. Este estudo apresenta a primeira avalia??o da influ?ncia de nanopart?culas de celulose bacteriana e de membranas de celulose bacteriana com superf?cie modificada por plasma (CBP) no comportamento e genotoxicidade celular. Inicialmente, a prolifera??o celular foi avaliada com o teste MTT e danos ao DNA foram avaliados utilizando-se os testes Cometa e Kado, sob a influencia das concentra??es de 0,1; 0,5 e 1,0 mg/ml de nanofibras de CB em contato com fibroblastos 3T3 e c?lulas CHO-K1. Os resultados obtidos nessas an?lises revelaram que a prolifera??o celular, para os dois tipos de c?lulas, foi cerca de 15-20% menor na presen?a de NFs, ap?s 72h de cultivo celular, independentemente da concentra??o utilizada, estas tamb?m n?o promoveram dano significativo ao DNA. Em um segundo trabalho, membranas de celulose bacteriana foram submetidas ao plasma em atmosfera contendo 70%N2 e 30% de O2. Posteriormente foram caracterizadas por MEV e AFM e submetidas aos ensaios cometa, micron?cleo, de ades?o e prolifera??o celular. Os resultados revelaram que o plasma modificou a superf?cie da CBP produzindo uma rugosidade de aproximadamente 70? 5,1 nm. Na CBP, as c?lulas tornaram-se mais alongadas com prolifera??o maior, provavelmente, influenciadas pelo aumento da rugosidade da superf?cie. A nova superf?cie gerada tamb?m n?o foi xii genot?xica. Face ao exposto, este estudo gerou um novo biomaterial que pode ser testado in vivo com futuro potencial para implante artificial

β-glucosidases are important components of the cellulase enzyme system in which they not only hydrolyse cellobiose to glucose, but also remove the feedback inhibition effects of cellobiose on exoglucanase and endoglucanase thereby increasing the rate of cellulose degradation to fermentable sugars. A total of 166 proteins were identified as β-glucosidases after manual BLASTp search on the Aspergillus comparative database from eight species. Evidence for Horizontal Gene Transfer (HGT) of bacterial origin of some β-glucosidase genes was provided by their lack of introns, absence of some fungal specific amino acid insertions in their sequences and unusual positions in phylogenetic trees showing similarities to bacterial proteins. A rapid plate assay based on Congo red methods was developed to study the optimum parameters such as pH and temperature for growth of strains and activities of the enzymes produced. Bacterial cellulose (BC) was produced by Gluconacetobacter xylinus. For the first time a fully detailed characterization by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), X-ray diffraction (XRD), Differential scanning calorimeter (DSC), Thermogravimetric analysis (TGA) and 13Carbon Solid State Nuclear Magnetic Resonance (SSNMR) of pure BC before and after treatment with a commercially available Aspergillus cellulase enzyme was demonstrated. Two encoding sequences for novel Aspergillus nidulans hydrophobin genes ANID_05290.1 and ANID_07327 that do not fall into either the class I or class II category of hydrophobins were successfully cloned. Two encoding sequences for a novel β-glucosidase gene from an Aspergillus niger strain from Nigeria were amplified and cloned from genomic DNA using PCR. Aspergillus nidulans β-glucosidases (AN2227 and AN1804) expressed in Pichia were purified to homogeneity by using ammonium sulphate precipitation and DEAE-Sephadex A-50 chromatography. Both enzymes had a remarkably broad pH and temperature profile. Further experiments on the development of a technology for lignocellulose degradation based on co-production of β-glucosidase with hydrophobin for biofuel production are suggested.

[pt] Nas últimas décadas a tecnologia de displays e células solares evoluiu consideravelmente. Há menos de cinco décadas atrás a tecnologia de volume (bulk) era a mais amplamente utilizada no mundo. Com o surgimento das tecnologias de dispositivos planos ocorreu uma grande revolução e, nos dias atuais, é a tecnologia dominante na área de displays e de células solares. Já a tecnologia do futuro surgiu com a descoberta dos materiais orgânicos semicondutores tornando possível a substituição dos convencionais substratos de vidro por substratos flexíveis, como os substratos poliméricos ou metálicos. Nesta tese foram desenvolvidos diferentes tipos de substratos compósitos poliméricos baseados no termoplástico comercial de alto desempenho, poli(éter imida) (PEI), e na celulose bacteriana (CB), um polímero natural e biocompatível comumente utilizado como pele artificial. Os nanocompósitos foram idealizados para aplicação como substratos flexíveis em dispositivos orgânicos. Três tipos de substratos foram estudados: nanocompósito PEI/nanotubos de carbono (CNTs); nanocompósito CB/PEI; e CB modificada por camada de dióxido de titânio dopado com alumínio (AlTiO2). Os dois primeiros substratos foram utilizados na produção de dispositivos orgânicos emissores de luz (OLEDs), enquanto o último na produção de um dispositivo fotodetector em meio aquoso – implante de retina. Os novos materiais foram caracterizados, principalmente, por suas propriedades ópticas e morfológicas, e os resultados foram utilizados para determinar suas possíveis aplicações. O nanocompósito PEI/CNT apresentou propriedades similares ao polímero puro quando produzido com baixas concentrações de CNTs. Para maiores concentrações os resultados obtidos mostraram-se inferiores aos do polímero puro. Já o nanocompósito CB/PEI apresentou propriedades comparáveis ou melhores que dos polímeros puros. Podemos destacar a grande melhoria em sua transparência óptica na região do visível, além de ter sido possível a obtenção de uma rugosidade superficial comparável à encontrada para substratos de vidro e com maior homogeneidade em relação aos substratos de PEI. Ambos substratos foram funcionalizados pela deposição de uma camada de óxido de índio-estanho (ITO), que foi utilizado como eletrodo transparente na produção dos OLEDs. A análise da funcionalização da superfície mostrou que os filmes de ITO sobre os compósitos apresentou propriedades elétricas também comparáveis aos obtidos para substratos de vidro e PEI. No caso do substrato de CB/PEI foi verificada melhor estabilidade do filme de ITO nos testes de flexão, não sendo observado variações no valor de sua resistividade mesmo após sofrer flexão de 5mm de diâmetro. Os dispositivos produzidos no substrato compósito PEI/CNT também apresentaram propriedades semelhantes às obtidas pela utilização do polímero puro. A maior eficiência atingida por ambos dispositivos flexíveis chegou a 1,45 cd/m2, ainda abaixo dos valores obtidos para os substratos de vidro – 2,15 cd/m2 no caso do substrato com ITO comercial e 2,00 cd/m2 no caso do substrato com ITO depositado. Já os dispositivos produzidos no nanocompósito CB/PEI apresentou excelente eficiência (2,50 cd/m2), sendo maior que o obtido para subtratos revestidos com ITO comercial. O substrato de CB/AlTiO2 foi idealizado para melhorar a aderência do ITO no filme de CB quando em contato com a água. O resultado obtido foi bastante satisfatório, pois, além de manter a camada de ITO aderido ao substrato, melhorou em 46 porcento sua rugosidade superficial. Essa modificação na morfologia da superfície acarretou em uma melhora significativa da resistividade elétrica do filme de ITO sobre o substrato flexível, uma redução de aproximadamente 63 porcento. Os substratos modificados foram utilizados para a produção de um dispositivo fotodetector. Os resultados obtidos apontam substratos promissores para a produção de implantes de retinas flexíveis e biocompatíveis. / [en] Over the past decades displays and solar cells technology had substantially evolved. For less than five decades ago the bulk technology was the most widely used worldwide. With the emergence of flat device technology a great revolution has occurred and, nowadays, this is the dominant technology in the field of displays and solar cells. The future technology has begun with the discovery of the organic semiconductor material which makes possible to replace conventional glass substrates for flexible substrates such as polymeric or metallic ones. In this thesis different types of polymeric composite substrates based on commercial high performance thermoplastic polyetherimide (PEI), and a natural and biocompatible polymer commonly used as artificial skin, bacterial cellulose (BC) has been developed. The above mentioned nanocomposites were developed for application as flexible substrates in organic devices. Three types of substrates were studied: PEI/carbon nanotubes (CNTs) nanocomposite; BC/PEI nanocomposite; and BC modified with an aluminum doped titanium dioxide (AlTiO2) layer. The first two substrates were used for the production of organic emitting devices (OLEDs), while the latter one was used for the production of a photodetector device in aqueous medium – retinal prosthesis. The new materials were mainly characterized by its optical and morphological properties and the results were used to determine its possible applications. PEI/CNT nanocomposite presented similar properties to the pure polymer when produced with low CNTs contents. For higher concentrations the results were inferior to those of the pure polymer. BC/PEI nanocomposite has showed comparable or better properties when compared with pure polymers. A highlight was the great improvement in their optical transparency in the visible region of electromagnetic spectrum, and the smooth surface achieved by the nanocomposite – comparable to that found for glass substrates and with better uniformity in relation to PEI substrates. Both substrates were functionalized by depositing a layer of tin doped indium oxide (ITO), which was used as a transparent electrode in the production of OLEDs. The analysis of surface functionalization showed that electrical properties of ITO films onto composites were also comparable to those obtained for glass and PEI substrates. However, BC/PEI substrate presented better ITO film stability in bending tests, showing no changes in its resistivity value even after undergoing 5 mm diameter of bending. The devices produced in the PEI/CNT composite substrate has also similar properties to those obtained by using pure polymer. The higher efficiency achieved by both flexible devices reached 1.45 cd/m2 which is still below the values obtained for the glass substrates – 2.15 cd/m2 in the case of commercial ITO substrate and 2.00 cd/m2 in the case the substrate with deposited ITO. The devices produced onto CB/PEI composite substrates showed excellent efficiency (2.50 cd/m2), a higher value than that obtained for substrates coated with commercial ITO. The CB/AlTiO2 substrate was designed to improve the adhesion of the ITO film onto BC substrate when in contact with water. The result was quite satisfactory, because in addition to maintaining the ITO layer adhered to the substrate it has a 46 percent improvement in surface roughness. This change in surface morphology resulted in a significant improvement of ITO electrical resistivity, a reduction of approximately 63 percent was observed. The modified substrates were used for production of a photodetector device and the results showed a promising substrate for production of biocompatible and flexible retinal prosthesis.

Orientador: Sidney José Lima Ribeiro / Resumo: Este trabalho descreve o desenvolvimento de membranas de cellulose bacterianas (BCM), econômicas e ecologicamente amigáveis com propriedades funcionais. Nanopartículas de sílica esféricas com tamanho de partícula de cerca de 51 ± 4 nm, obtidas pelo método sol-gel e nanopartículas de sílica com tamanho de partículas heterogêneo, extraídas da casca de arroz, foram preparadas e funcionalizadas pelas metodologias in situ e post-grafting, respectivamente, com alcoxisilanos com propriedades easy-cleaning e curcuma. Nanocompósito de anatase SiO2@TiO2 preparado pelo método sol-gel, também foi desenvolvido. Posteriormente, estes nanomateriais funcionais e os organosilanos 1,4 – bis(trietoxissilil)benzeno (BTEB), Bis(trietoxisililpropil)disulfeto (BTPD) and 1,2-Bis(trietoxissilil)etano (BTSE), foram imobilizados com sucesso na BCM, segundo as metodologias in situ e post-grafting. Na BCM funcionalizada com os organosilanos BTEB, BTPD e BTSE, nanopartículas de sílica esféricas com estrutura porosa e distribuição de tamanho de partícula heterogêneo, foram formados nas fibras de celulose. A repelência da BCM funcionalizado com nanopartículas de sílica contendo propriedades de limpeza facilmente melhorada notavelmente. BCM apresenta fobicidade à água, tolueno, cicloexano e solução de suor artificial. Especificamente, a BCM funcionalizada com a amostra SiO2@F13TES segundo as metodologias in situ e post-grafting, apresentam uma superfície quase superhidrofóbica (> 150°). As medições de decomp... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: This work reports the development of economic and environmentally friendly Bacterial Cellulose Membrane (BCM) with functional properties. The spherical mesoporous silica nanoparticles with average particle size around 51 ± 4 nm, obtained by sol-gel method and spherical silica nanoparticles with heterogeneous particles size distribution (20-40 nm) obtained through agro-industrial waste were prepared and functionalized by in situ and post-grafting methodology, respectively, with alkoxysilanes with easy-cleaning properties and natural dye obtained through natural extracts, namely curcuma. Anatase TiO2@SiO2 spherical nanocomposites prepared by the sol-gel method, have also been developed. Subsequently, these functional nanomaterials and the organosilanes 1,4 – bis(triethoxysilyl)benzene (BTEB), Bis(triethoxysilylpropyl)disulfide (BTPD) and 1,2-Bis(triethoxysilyl)ethane (BTSE), were successfully incorporated into BCM, by in situ and post-grafting methodologies. In the BCM functionalized with BTEB, BTPD and BTSE, spherical silica nanoparticles with porous structure and heterogeneous particle size, were formed on the cellulose fibers. The surface repellency of the functionalized BCM with silica nanoparticles containing easy-cleaning properties was remarkably enhanced. This BCM displaying phobicity to water, toluene, cyclohexane and artificial sweat. Specifically, the BCM functionalized by in situ and post-grafting with SiO2@F13TES, displayed a surface almost superhydrophobic (> 150°... (Complete abstract click electronic access below) / Doutor

El presente trabajo tiene por objetivo estudiar las aplicaciones de los nanocristales o ¿nanowhiskers¿ extraídos mediante hidrólisis ácida de celulosa bacteriana (BCNW) para el desarrollo de materiales poliméricos y biopoliméricos con propiedades mejoradas para su uso en aplicaciones de envasado de alimentos. En primer lugar se estudió y optimizó el proceso de extracción de BCNW. Se desarrolló un procedimiento de extracción con ácido sulfúrico, que permitió obtener nanocristales con elevada relación de aspecto y cristalinidad y al mismo tiempo, un elevado rendimiento de extracción. Este procedimiento comprende una posterior etapa de neutralización que resultó ser necesaria para garantizar la estabilidad térmica de los nanocristales. El siguiente paso consistió en la formulación de materiales nanocompuestos con propiedades mejoradas incorporando BCNW en diferentes matrices plásticas, en concreto copolímeros de etileno-alcohol vinílico (EVOH), ácido poliláctico (PLA) y polihidroxialcanoatos (PHAs). Mediante las técnicas de electroestirado y estirado por soplado se generaron fibras híbridas de EVOH y PLA con BCNW. La incorporación de BCNW en las disoluciones empleadas para producir fibras modificó significativamente sus propiedades (viscosidad, tensión superficial y conductividad) y por tanto, la morfología de las fibras se vio afectada. Además, se generaron fibras con propiedades antimicrobianas mediante la incorporación de aditivos, maximizando el efecto antimicrobiano con la adición de sustancias de carácter hidrofílico. Seguidamente, se produjeron nanocompuestos por mezclado en fundido y se desarrollaron técnicas de pre-incorporación de BCNW para evitar la aglomeración de los mismos no sólo en matrices hidrofílicas como el EVOH, sino también en matrices hidrofóbicas como el PLA. La dispersión óptima de BCNW resultó en una mejora de las propiedades mecánicas y de barrera de los nanocompuestos. También se estudió la modificación de la superficie de los nanocristales mediante copolimerización con poli(glicidil metacrilato) para mejorar la compatibilidad de BCNW con una matriz hidrofóbica como el PLA. Se incluyen además los primeros resultados obtenidos en cuanto a la producción de nanobiocompuestos sintetizados por microorganismos, que consisten en PHAs con diferentes contenidos de hidroxivalerato reforzados con BCNW. Por último, se desarrollaron películas con propiedades de alta barrera basadas en películas de BCNW recubiertas con capas hidrofóbicas. El recubrimiento mediante la deposición de fibras por electrospinning seguido de homogeneización por calentamiento garantizó una buena adhesión entre las diferentes capas, protegiendo así las películas de BCNW del efecto negativo de la humedad. / Martínez Sanz, M. (2013). Bacterial cellulose nanowhiskers to enhance the properties of plastics and bioplastics of interest in food packaging [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/30312 / TESIS / Premios Extraordinarios de tesis doctorales