O presente trabalho tem como objetivo principal a eletrofiação de nanofibras poliméricas de poliacrilonitrila (PAN) e polifluoreto de vinilideno (PVDF), incorporadas com negro de fumo (NF) e ftalocianina de cobre (CuPc), visando aplicações em dispositivos sensores. Inicialmente foram preparadas soluções de PAN puro a 6 % em peso e PVDF puro a 20% em peso e foram misturadas a essas soluções partículas de negro de fumo e ftalocianina de cobre, obtendo soluções de PAN/NF, PVDF/NF, PAN/CuPc e PVDF/CuPc. Foi determinada a viscosidade absoluta das soluções. Realizou-se a eletrofiação para obtenção de nanofibras que foram caracterizadas segundo o diâmetro e morfologia, usando microscópio óptico e microscópio eletrônico de varredura. Para avaliar as interações polímero-polímero, polímero-partícula foram analisadas por espectroscopia FITR e Raman. Com as fibras de PAN/NF foi analisada a resistência e condutância elétrica das membranas usando um picoamperímetro digital, visando aplicação como filtro eletrostático. Foi construído canal na lâmina de silício usando um feixe de laser visando a deposição de fibras dentro do canal usando a técnica de focagem eletrodinâmica com tensão aplicada em máscaras de cobre. Foi usada a técnica da microbalança de cristal de quartzo para determinar a variação de massa adsorvida por membranas de PAN/CuPc e PVDF/CuPc por meio da medida da variação de frequência usando um frequencímetro digital, onde se observou que essas membranas são promissoras para atuar como sensores de vapor de amônia. / The main objective of this work is the incorporation of different particles in order to electrospun polymeric nanofibers of polyacrylonitrile (PAN) and polyvinylidene fluoride (PVDF), aiming at applications in sensor devices. Initially, solutions of PAN pure 6 wt% and PVDF pure 20 wt% were prepared and these solutions were mixed with carbon black (NF) particles and copper phthalocyanine (CuPc), obtaining solutions of PAN/NF, PVDF/NF, PAN/CuPc and PVDF/CuPc. The absolute viscosity of the solutions was determined. The electrospinning was performed to obtain nanofibers that were characterized according to the diameter and morphology, using optical microscope and scanning electron microscopy. To evaluate the polymer-polymer and polymer-particle interactions, FITR and Raman spectroscopy were performed. The resistance and conductance of the membranes electrospun from PAN/NF solution were analyzed using a digital picoammeter, and an increase in the resistance was measured. This result shows that the membrane is suitable to be applied as electrostatic filter. A channel was constructed on the silicon wafer using a laser beam for the deposition of fibers inside the channel using the electrodynamic focusing technique. The quartz crystal microbalance technique was used to determine the applicability of the membranes as sensor layer. The results of PAN/CuPc and PVDF/CuPc membranes suggests that these membranes are promising to act such as ammonia vapor sensors.

Made available in DSpace on 2017-07-21T20:43:45Z (GMT). No. of bitstreams: 1 Raysa Frankievicz.pdf: 2669303 bytes, checksum: 9e7cf92368c675d33a730546ebb1fccc (MD5) Previous issue date: 2014-08-13 / Due to environments problems caused by synthetic plastic, there is currently a search for replacing these materials with biodegradable materials. The study related to composites and nanocomposites formed from biodegradable materials and synthetic matrices has increased last years, and it has shown that these materials are very promising respect to biodegradation processes, besides presenting better properties than their pure components. In this work, it has been emphasized the production of nanofibers bacterial cellulose composite in a polypropylene matrix. The production of nanofibers from bacterial cellulose (BC) has been made in colloid mill. The material has been processed in a twin screw extruder in proportions of 1 %, 3% and 5% (w/w) of bacterial cellulose and coupling agent has been used as graphitized PP with maleic anhydride. The samples have been characterized by thermogravimetric analysis (TGA), x-ray diffraction (XRD), rheological characterization, infrared spectroscopy (FTIR), colorimetry, scanning electron microscopy (SEM), and tensile strength and impact. The TGA results have shown a single stage of mass loss for all samples, and thermal stability increase with filler concentration increase, which can be associated with the fiber-matrix interactions. In the XRD results, the PP has showed only the α phase remaining in the samples containing CB. In the rheological analysis, the complex viscosity has been maintained for samples containing 1% and 3% CB and pure PP, decreasing only for the 5% CB. In additional, It has been observed an enlargement of the molar mass distribution through a tendency reduction in the intersection point of G' and G". In the tensile strength, the elastic modulus has not undergone significant changes, the yield stress has decreased according to the load increasing, however it there have been significant changes with the load concentration increment. The impact strength has decreased for all samples with CB compared to pure PP. The microscopy has showed a good adhesion between fiber and matrix with bacterial cellulose clusters formation. By colorimetry process, it has been found caramelization of bacterial cellulose during the process of extrusion and injection, which causes browning of the samples. / Devido aos problemas ambientes causados pelos plásticos sintéticos, existe atualmente uma busca pela substituição desses materiais por materiais biodegradáveis. O estudo em relação a compósitos e nanocompósitos formados por materiais biodegradáveis e matrizes sintéticas vem crescendo nos últimos anos. Tem-se demostrado que esses materiais são muito promissores em relação aos processos de biodegradação, além de apresentarem propriedades melhores do que seus componentes puros. Neste trabalho foi visada a produção de um compósito com celulose bacteriana nanofibrilada em uma matriz de polipropileno. A produção das nanofibras de celulose bacteriana (CB) foi realizada em moinho coloidal. O material foi processado em extrusora dupla rosca nas proporções de 1%, 3% e 5% (p/p) de celulose bacteriana e como agente compatibilizante foi utilizado PP grafitizado com anidrido maleico. As amostras foram caracterizadas por análise termogravimétrica (TGA), difratometria de raio-x (DRX), espectroscopia de infravermelho (FTIR), análise reológica, resistência a tração e impacto, microscopia eletrônica de varredura (MEV) e colorimetria. Os resultados de TGA demostraram um único estágio de perda de massa para todas as amostras, e um aumento da estabilidade térmica conforme aumenta a concentração de carga, que pode estar associado com as interações fibra-matriz. Nos resultados de raio-x o PP apresentou apenas a fase α, mantendo-se para as amostras contendo CB. Nas análises reológicas, a viscosidade complexa manteve-se para as amostras de 1% e 3% de CB e para o PP puro, diminuindo apenas para a amostra com 5% de CB. Também observou-se um alargamento da distribuição da massa molar através de uma tendência na redução do ponto de cruzamento de G’ e G”. Na resistência à tração, o módulo elástico não sofreu alterações significativas, a tensão de escoamento reduziu com a inserção de carga, porém, não houve variação significativas com o aumento da concentração da carga. A resistência ao impacto reduziu para todas as amostras contendo celulose bacteriana em relação ao PP puro. A microscopia revelou uma boa adesão entre a fibra e a matriz com a formação de aglomerados de celulose bacteriana. Através da colorimetria verificou-se o processo de caramelização da celulose bacteriana durante o processo de extrusão e injeção, o que provoca o escurecimento das amostras.

The anterior cruciate ligament (ACL) is the most frequently injured ligament of the knee, with upwards of 100,000 ACL reconstructions performed annually. Current grafting techniques are limited by insufficient integration with subchondral bone and donor site morbidity issues related to graft harvest, potentially resulting in revision surgery and long-term joint pain. Therefore, significant demand exists for alternative grafting solutions that do not require additional surgery and can regenerate the native ACL-to-bone interface to promote biological fixation of the implanted ACL graft. To address this need, the ideal system must be able to withstand the functional demands of the native tissue by demonstrating physiologically equivalent mechanical properties, be comprised of compositionally varying phases in order to recapitulate the inherent heterogeneity of the native ligament to bone transition and be biodegradable such that it is gradually replaced by the regenerated tissue following implantation. It is hypothesized that a biomimetic, multi-phased scaffold comprised of optimized bone, interface and ligament regions coupled with controlled chemical and/or mechanical stimulation in vitro will guide phase-specific differentiation of mesenchymal stem cells (MSC) and result in a biologically integrated bone-ligament-bone complex in vivo. Mesenchymal stem cells are particularly attractive for this application as they can be routinely harvested from bone marrow, have been shown to respond to chemical, mechanical and structural cues, and are capable of differentiating towards the primary cell types (fibroblasts, osteoblasts and chondrocytes) found within ligament, bone and the ligament-to-bone interface. To this end, a nanofiber-based synthetic graft was designed with compositionally-varying phases to regenerate ligament, bone and interface tissues. The ligament phase was optimized in terms of nanofiber alignment, composition, mechanical stimulation and chemical stimulation. It was demonstrated that an aligned nanofiber substrate coupled with controlled mechanical stimulation was necessary to differentiate MSCs towards a fibroblastic phenotype. The bone phase was optimized in terms of ceramic content and it was shown that a threshold of mineral incorporation into nanofibers was necessary to differentiate MSCs towards an osteogenic phenotype. Lastly, a mechanoactive nanofiber collar was designed to induce interface formation. It was demonstrated that compressive stimulation applied via nanofiber collar contraction induced chondrogenic differentiation of MSCs. Subsequently, the three phases were incorporated to form a synthetic graft, for which graft architecture and cell seeding density were optimized. The resulting graft was cultured in vitro under the optimized parameters, demonstrating the formation of distinct and structurally continuous regions of bone, interface and ligament tissue. The graft was implanted in vivo where it was shown to be suitable for ACL reconstruction as it maintained knee stability and promoted ligament regeneration. In summary, this thesis focuses on the design of a biomimetic, nanofiber-based, integrated bone-ligament-bone construct, and elucidates chemical, mechanical and scaffold design-related parameters that can guide MSC differentiation towards desired tissue types. The impact of these studies extends beyond ligament reconstruction as they yield valuable scaffold design criteria, establish scaffold and culturing-related parameters to induce stem cell differentiation and can readily be applied to the formation of interfaces between soft-to-hard tissues as well as other complex tissues.

Les glioblastomes multiformes (GBM) comptent parmi les tumeurs au pronostic le plus sombre. L’extraordinaire capacité invasive des cellules tumorales rend toutes les interventions thérapeutiques actuelles totalement impuissantes. Une sous-population de Cellules Souches de Glioblastome (CSG) hautement invasive est responsable de la récurrence tumorale. Dans le cerveau, les GBM migrent principalement le long des vaisseaux sanguins au sein de l’espace périvasculaire riche en laminine, fibronectine et collagène ainsi qu’en suivant l’alignement des fibres myélinisées du corps calleux. La Matrice Extracellulaire (MEC) de ces régions joue un rôle important dans l’invasion des GBM, mais les mécanismes mis en jeu n’ont pas été complètement dévoilés. De plus, le développement de nouvelles thérapies anti-migratrices ciblant l’interaction des GBM avec la MEC reste encore limité. Dans le but de mimer la composition biochimique et les propriétés mécaniques de la MEC cérébrale et d’étudier leur rôle(s) dans la migration des CSG, nous avons développé un nouveau support de nanofibres (NF) alignées et fonctionnalisées avec de la laminine. Mes travaux de thèse ont montré que les NF génèrent un microenvironnement tridimensionnel (3D) favorisant l’adhésion et la migration des CSG. Cette adhésion est améliorée en comparaison avec les supports planaires (SP) conventionnels (2D) et récapitule mieux les mécanismes d’interaction des CSG avec la MEC au cours de l’invasion dans le modèle murin de tumeurs xénogreffées. Dans ces conditions physiologiques plus convenables générées par les NF, la variation des composantes biochimiques et mécaniques de la MEC affecte la migration des CSG. La présence ou l’absence de laminine régule le mode migratoire et l’orientation de fibres contrôle la direction de migration des CSG. D’un autre coté, l’altération de la glycosylation des protéines de la surface cellulaire module l’interaction des cellules tumorales du cerveau avec la MEC et augmente leur invasion. La deuxième partie de mes travaux de thèse a permis de démontrer que les glycomimétiques phostines « 3.1a » réorganisent le processus de la N-glycosylation des CSG diminuant leur invasivité in vitro et in vivo en inhibant les voies de signalisation de la kinase FAK et du récepteur de TGF-β impliqués dans l’interconnexion cellule-MEC. / Glioblastoma Multiforme (GBM) is a biologically aggressive tumor with an extremely poor prognosis. The highly invasive capacity of a subpopulation of Glioblastoma Initiating Cells (GIC) makes complete surgical resection impossible. GBM dissemination occurs along preexisting brain structures such as the perivascular space rich in laminin, fibronectine and collagen as well as the aligned myelinated fibers of the corpus callosum. The Extracellular Matrix (ECM) of these cerebral regions plays an important role during GBM invasion, but the underlying mechanisms remain largely unknown. Accordingly, the development of new anti-migratory therapies targeting the cell-ECM interactions is lacking. In order to mimic the compositional and physical properties of the cerebral ECM and to investigate their role(s) in GBM invasion, we have set up a new aligned nanofibers (NF)scaffold functionalized with laminin. My work demonstrated that the NFs constitute a tridimensional (3D) microenvironment supporting GIC adhesion and migration. The cell-ECM adhesion is improved on the NF in comparison to the conventional 2D planar surfaces (PS). Furthermore, the mechanisms of GIC interaction with the ECM on the NF are similar to those observed in the human GBM xenograft murine model. In this physiologically more relevant 3D microenvironment reproduced by the NF, the variation of the different biochemical and mechanical components of the ECM affects the migration of GIC. The presence or absence of laminin on the NF regulates the mode of migration and the orientation of the fibers dictates the direction of migration of GIC. On the other hand, the glycosylation that decorates cell surface proteins modulates the interaction of GBM tumor cells with the ECM and its alteration increases their invasion. The second part of my thesis demonstrated that the glycomimetics phostines « 3.1a » remodel the N-glycosylation of GIC and decrease their invasivity in vitro and in vivo via the inhibition of FAK and TGFβ-R signaling pathways known to be implicated in the cell-ECM intercommunication.

<p>Validerat; 20130918 (global_studentproject_submitter)</p>

Submitted by Marilene Donadel (marilene.donadel@unioeste.br) on 2019-02-06T18:22:36Z No. of bitstreams: 1 Leonardo_Megliorini_2018.pdf: 2265228 bytes, checksum: 5bec59af67778babe3b2590c1a6bf0f2 (MD5) / Made available in DSpace on 2019-02-06T18:22:36Z (GMT). No. of bitstreams: 1 Leonardo_Megliorini_2018.pdf: 2265228 bytes, checksum: 5bec59af67778babe3b2590c1a6bf0f2 (MD5) Previous issue date: 2018-07-27 / Nitrofurazone is a drug used to treat burns and skin transplants. The drug product is salled in cream and solution form. The ecovio® polymer is composed of poly(lactic acid) / poly(butylene adipate co-teraphtalate) and is biocompatible. In this work a film with the combination of ecovio® and nitrofurazone was produced by the electrospinning technique forming nanofibers. Two films were produced. The first was produced with dimethylformamide / tetrahydrofuran (15:85 v / v) and was capable of releasing 100% of the nitrofurazone reproducibly in the dissolution profile test evaluated for 300 minutes. The second film was produced with dimethylformamide/chloroform (15:85 v/v) and released about 90% of the nitrofurazone. But did not show reproducible results in the same range. Physicalchemical analyzes lead to the conclusion that the interaction of nitrofurazone with the polymer occurs mainly among the more polar groups. The dissolution test was performed following pharmacopoeial parameters. The quantitation of the released nitrofurazone was performed by UV-Vis spectrophotometry at 375 nm. The method used was validated and proved to be adequate, showing linearity in range 0.25 - 12.50 mg.L-1 with correlation coefficient 0.9999, high precision with relative standard deviation ≤ 1.6%, accuracy 98.9 - 100.4%, selectivity and limit of quantification 0.4 mg.L-1. / A nitrofurazona é um fármaco utilizado no tratamento de queimaduras e em transplantes de pele. O medicamento é comercializado na forma de pomada e solução. O polímero ecovio® é composto de poli(ácido lático)/poli(butileno adipato coteraftalato) e é biocompatível. Neste trabalho foi produzido um filme com a combinação de ecovio® e nitrofurazona pela técnica de eletrofiação formando nanofibras. Dois filmes foram produzidos. O primeiro foi produzido com dimetilformamida/tetrahidrofurano (15:85 v/v) e foi capaz de liberar 100% da nitrofurazona de forma reprodutível no teste de perfil de dissolução avaliado por 300 minutos. O segundo filme foi produzido com dimetilformamida/clorofórmio (15:85 v/v) e liberou cerca de 90% da nitrofurazona, mas não apresentou resultados reprodutíveis no mesmo intervalo. Análises físico-químicas levam à conclusão de que a interação da nitrofurazona com o polímero ocorre principalmente entre os grupamentos mais polares. O teste de dissolução foi realizado seguindo parâmetros farmacopeicos. A quantificação da nitrofurazona liberada foi realizada por espectrofotometria na região do UV-Vis em 375 nm. O método utilizado foi validado e comprovou-se estatisticamente que é adequado, apresentando linearidade no intervalo de 0,25 a 12,50 mg.L-1 com coeficiente de correlação de 0,9999, precisão elevada com desvio padrão relativo ≤ 1,6%, exatidão de 98,9 a 100,4%, seletividade e limite de quantificação de 0,4 mg.L-1.

Com o aumento da expectativa de vida e o envelhecimento da população, a medicina regenerativa vem ocupando um importante espaço visando manter a qualidade de vida da população. A engenharia de tecidos, apoiada nos avanços da biotecnologia e da nanotecnologia, vem se configurando como alternativa mais versátil e menos custosa ao reparo e transplante de tecidos e órgãos. Os arcabouços para engenharia tecidual constituídos de nanofibras têm o potencial para mimetizar a arquitetura nanométrica dos tecidos humanos, especialmente devido à grande área superficial e elevada porosidade. Para a fabricação de arcabouços de nanofibras, a técnica mais utilizada é a de eletrofiação, devido à sua alta versatilidade, e os materiais mais estudados são os polímeros biodegradáveis e biocompatíveis, que são os mais desejados para fins biomédicos. A esterilização é uma etapa crítica no processo de fabricação de produto médico implantável e pode ter impacto no desempenho dos arcabouços poliméricos. Desta forma, o objetivo deste estudo foi avaliar o impacto da esterilização por gás ozônio em arcabouços de nanofibras poliméricas eletrofiadas para engenharia de tecidos. A esterilização por ozônio foi eficaz na inativação do indicador biológico G. stearothermophilus, caracterizando eficácia na letalidade microbiana; igualmente, não se detectou crescimento microbiano no teste de esterilidade. Os arcabouços de nanofibras de poli(ácido láctico-co-ácido glicólico) tiveram suas propriedades físico-químicas, mecânicas e biológicas preservadas, mantendo o mesmo desempenho como suporte para o crescimento de fibroblastos NIH3T3 após a esterilização. Já os arcabouços de poli-caprolactona, tiveram suas propriedades alteradas e apresentaram um melhor desempenho na proliferação celular de fibroblastos L929 após a esterilização. Assim, o gás ozônio se mostrou como um método alternativo para a esterilização de nanofibras poliméricas para engenharia tecidual. / Since world population is ageing, regenerative medicine has become a growing area in the medical field in order to maintain the life quality of population. With the advance of biotechnology and nanotechnology, tissue engineering has emerged as a more versatile and less costly alternative to tissue repair and transplantation. Nanofibers have the potential to mimic the human tissue architecture at the nanometer scale, especially due to their large surface area and high porosity. Electrospinning is the most applied technique to fabricate nanofibers scaffolds mainly because of its powerful and high versatility. Many polymers can be used on the fabrication of nanofibers scaffolds; however, the biodegradable and biocompatible polymers are the most desired ones for biomedical purposes. Sterilization is a critical step in the fabrication process and might impact the performance of polymeric scaffolds. Therefore, the aim of this study was to evaluate the impact of sterilization by ozone gas on polymeric electrospun nanofibers scaffolds for tissue engineering. Ozone gas sterilization was efficient in killing the G. stearothermophilus spores, a common biological indicator used for validation of sterilization processes. The sterilization method preserved the physico-chemical, mechanical, and biological properties of poly(lactic-co-glycolic) acid nanofibers, keeping the performance of NIH3T3 proliferation on the scaffolds. On the other hand, the same sterilization method altered some properties of poly-caprolactone electrospun scaffolds, what improved L929 fibroblasts proliferation on the scaffolds after sterilization. Therefore, ozone gas was found to be a benign sterilization method for polymeric electrospun scaffolds for tissue engineering.

O objetivo do presente estudo foi de avaliar a influência de soluções de resina com diferentes proporções de monômeros e diferentes concentrações em massa de nanofibras nas propriedades flexurais de compósitos resinosos experimentais reforçados com nanofibras de poliacrilonitrila (PAN). Materiais e métodos: Nanofibras de PAN foram produzidas pelo processo de eletrofiação e caraterizadas por teste de tração e microscopia eletrônica de varredura (MEV). Os compósitos experimentais foram produzidos pela infiltração das mantas de nanofibras com diferentes misturas de BisGMA-TEGDMA (BisGMA/TEGDMA: proporções em % massa de 30/70, 50/50, e 70/30). Foram incorporadas diferentes concentrações em massa de nanofibras (de 0% a 8%). Espécimes em forma de barra foram seccionados a partir de blocos do compósito experimental e armazenados em água na temperatura de 37oC por 24h anteriormente à realização dos testes de flexão de três pontos. Foram avaliados a resistência flexural (RF), o módulo flexural (MF) e o trabalho de fratura (TF). Resultados: Os testes de tração das nanofibras de PAN demonstraram um comportamento anisotrópico das mantas de nanofibras. As propriedades mecânicas exibiram maiores valores na direção perpendicular ao eixo de rotação do coletor metálico utilizado na produção das fibras por eletrofiação. Maiores proporções de BisGMA nas misturas de resina resultaram em maiores valores de RF e MF, o que não ocorreu para os valores de TF. A adição de diferentes concentrações de nanofibras não afetou as propriedades de RF e MF em comparação com o grupo controle (resina pura) (p>0.05). No entanto, a adição das nanofibras promoveu um aumento significante do TF, principalmente para as misturas de resina com maior proporção de TEGDMA (p<0,05). Significância: A inclusão de nanofibras de PAN em resinas de modo a formar compósitos resinosos reforçados por nanofibras não afetou negativamente as propriedades flexurais do material e resultou em um aumento significativo da tenacidade, uma propriedade desejável para um material a ser utilizado para aplicação restauradora. / The present study had the objectives to evaluate the influence of different resin blends concentrations and nanofibers mass ratio on flexural properties of experimental Poliacrylonitrile (PAN) nanofibers reinforced composite. Materials and Methods: Poliacrylonitrile (PAN) nanofibers mats were produced by electrospinning and characterized by tensile testing and scanning electron microscopy (SEM). Experimental resin-fiber composite beams were manufactured by infiltrating PAN nanofiber meshs with varied concentrations of BisGMA-TEGDMA resin blends (BisGMA/TEGDMA: 30/70, 50/50 and 70/30 weight %). The mass ratio of fiber to resin varied from 0% to 8%. Beams were cured and stored in water at 37oC. Flexural strength (FS), flexural modulus (FM) and work of fracture (WF) were evaluated by three-point bending test after 24 hs storage. Results: The tensile properties of the PAN nanofibers indicated an anisotropic behavior being always higher when tested in a direction perpendicular to the rotation of the collector drum. Except for WF, the other flexural properties (FS and FM) were always higher as the ratio of BisGMA to TEGDMA increased in the neat resin beams. The addition of different ratios of PAN fibers did not affect FS and FM of the composite beams as compared to neat resin beams (p>0.05). However, the addition of fibers significantly increased the WF of the composite beams, and this was more evident for the blends with higher TEGDMA ratios (p<0.05). Significance: The inclusion of PAN nanofibers into resin blends did not negatively affect the properties of the composite and resulted in an increase in toughness that is a desirable property for a candidate material for restorative application.

El presente trabajo de Tesis Doctoral se centró en la preparación y en el estudio de las propiedades fotoelectroquímicas de electrodos nanoestructurados de dióxido de titanio compuestos por partículas de diferente morfología: nanopartículas, nanohilos, nanotubos, nanocolumnas y nanofibras. Por un lado se estudió la influencia de la fase cristalina (anatasa y rutilo) y por otro, la influencia del tamaño de las partículas y su morfología sobre las propiedades fotoelectroquímicas de electrodos nanoestructurados de dióxido de titanio. Para estudiar la influencia de la fase cristalina se prepararon electrodos de anatasa y rutilo con la misma morfología (nanohilos) y tamaño de partícula (~ 2nm). Estos electrodos se emplearon para estudiar la estructura electrónica de ambas fases cristalinas. También se realizó un estudio de la distribución de los estados electrónicos empleando electrodos con diferente morfología de nanopartículas (nanotubos, nanocolumnas, nanopartículas). Los estudios se llevaron a cabo empleando voltametría cíclica, cronoamperometría, cronopotenciometría y métodos espectroscópicos (espectroscopía ultravioleta-visible, espectroscopía de voltaje superficial y espectroscopía de resonancia paramagnética electrónica). Las propiedades fotoelectroquímicas para las diferentes nanoestructuras se estudiaron tanto en medio ácido como en medio alcalino empleando diferentes compuestos orgánicos modelo (ácido fórmico, metanol e hidracina). Se estudió la influencia del tratamiento térmico de los nanohilos sobre su cristalinidad y sus propiedades fotoelectoquímicas. También se prepararon estructuras organizadas jerárquicamente basadas en nanotubos de anatasa decorados con nanohilos tanto de anatasa como de rutilo. El efecto del sustrato se estudió comparando electrodos de nanotubos de dióxido de titanio preparados sobre titanio y sobre vidrio conductor. En el presente trabajo también se estudió la actividad de dióxido de titanio modificado con nanopartículas de oro en el rango visible del espectro empleando métodos espectroscópicos.

Small drinking water systems, often financially and resource-limited, face unprecedented challenges due to the current diversity and ubiquity of water pollutants. Well-characterized inorganic legacy pollutants, including arsenic, copper, hexavalent chromium, and lead, remain persistent in drinking water systems. In addition, emerging organic contaminants, like endocrine disrupting compounds and pharmaceuticals, are largely uncharacterized but prevalent in the environment and water supplies, calling into question what levels of these relatively new contaminants are truly safe in drinking water. Point-of-use (POU) and point-of-entry (POE) water treatment devices, installed at a specific tap or at the water entry point to a single facility, respectively, are necessary to ensure safe drinking water in contexts where centralized water treatment is not available or cannot adapt to meet new regulatory standards. While existing POU and POE technologies, including reverse osmosis and packed bed media filters, are effective for removing contaminants, installation costs, energy demands, and spatial footprints of these systems can inhibit their implementation. There is a need for new POU and POE technologies that remove a diversity of water contaminants while maintaining a small application footprint. Nanotechnology, referring to technology using material with at least one dimension or feature less than 100 nm in length, is ideal for meeting this need in drinking water treatment. With high surface area-to-volume ratios, nano-enabled treatment technologies exhibit enhanced reactivity with less material, keeping overall footprint relatively small. Specifically, electrospinning, a process in which a polymer precursor solution is electrified to produce a cohesive sheet of nanofibers, can be used to easily synthesize chemically active nanofiber filters for water treatment applications. In this study, we develop electrospun nanofiber filters that harness nano-scaled hematite (Fe2O3) for sorption of inorganic contaminants (e.g., As, Pb) and nano-scaled titanium dioxide (TiO2) for use with ultraviolet (UV) and visible light as an advanced oxidation process (AOP) for removal of emerging organic contaminants (e.g., benzotriazole, carbamazepine, DEET). Most importantly, we strive to optimize both reactivity and material strength to develop cohesive, durable filtration platforms that overcome barriers to use of nanomaterials in water treatment (e.g., concerns over leaching of nanoparticles deployed as suspensions). Herein, we first demonstrate reactivity optimization of pure (though brittle) TiO2 nanofiber photocatalysts by noble metal catalyst (Au) surface loading. Additionally, we optimize polymer-Fe2O3 composite nanofibers for reactivity while maintaining material flexibility by coating the doped polymer with additional Fe2O3 surfaces available for metal/metalloid uptake. Finally, we apply reactivity optimization and strategies to maintain material strength in the development of carbon/TiO2 nanofiber composites used for (photo)chemical filtration of water containing emerging organic contaminants. Ultimately, we find that nanofiber composites exhibit substantial reactivity and structural integrity in water treatment platforms. Outcomes of this work contribute to making nanomaterials, which have been studied for decades but have yet to be commercially employed for water treatment, practical for chemically active water filtration.