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- Desenvolvimento de Sistemas de Entrega de Fármacos Inovadores utilizando Materiais Poliméricos Porosos contendo NanocelulosePublication . Morais, Flávia Pinto; Curto, Joana Maria Rodriguesdesenvolvimento de Sistemas de Entrega de Fármacos utilizando materiais poliméricos biocompatíveis, recorrendo à manipulação de fibras de celulose na escala nano e à simulação computacional 3D constitui um exemplo de investigação multidisciplinar na área de Química Medicinal. O objetivo principal é o desenvolvimento de sistemas de entrega de fármacos constituídos por uma matriz polimérica 3D de nanocelulose, com otimização da porosidade, para aplicações em terapêuticas orais em que a libertação controlada apresenta vantagens relativamente aos sistemas existentes. Utilizou-se a celulose nanofibrilada, desconstruída a partir da celulose vegetal, comparando-a com a celulose bacteriana, e com a carboximetilcelulose. Foi possível obter sistemas de entrega de fármacos com cinéticas de libertação diferenciadas e caracterizar as matrizes produzidas utilizando imagens SEM. A caracterização das estruturas incluiu a quantificação das dimensões das fibras e dos poros, recorrendo a programas de análise de imagem. Verificou-se que os sistemas produzidos a partir de celulose nanofibrilada apresentavam distribuições de tamanhos de poro com maior variabilidade, o que se traduziu numa cinética de libertação irregular. Posteriormente efetuou-se a simulação computacional da matriz polimérica e verificou-se que seria possível obter com os mesmos elementos fibrosos uma matriz com uma distribuição de poros mais regular. Produziram-se essas estruturas partir da celulose nanofibrilada, controlando as condições de dispersão das cadeias poliméricas e formação da estrutura 3D do gel, por manipulação das variáveis de processo da filtração. Utilizou-se a reticulação de um polímero auxiliar, o alginato, de forma a fixar e manter a estrutura pretendida. A cinética de libertação do sistema de entrega de fármacos contendo a matriz otimizada permitiu concluir que a obtenção de poros mais regulares se traduziu numa libertação controlada mais uniforme e numa melhoria significativa do sistema. Finalmente, produziram-se sistema inovadores combinando a matriz 3D de celulose nanofibrilada com carboximetilcelulose, uma vez que se provou que a sua presença permite aumentar a afinidade com a água. Conclui-se que foi possível evitar a libertação do Diclofenac no pH acídico do estomago e que a simulação computacional 3D é uma ferramenta útil para projetar sistemas de libertação controlada para diferentes aplicações terapêuticas.
- Design and Engineering of Tissue Papers using Cellulose-based Fibrous Materials 3D Simulations: an approach for Furnish OptimizationPublication . Morais, Flávia Pinto; Curto, Joana Maria Rodrigues; Amaral, Maria Emília da Costa Cabral; Carta, Ana Margarida Martins SalgueiroIn recent years, the tissue paper industry has been exposed to several challenges related to the growing relevance and demand for raw materials (furnish) and sustainable products. Cellulose fibers are excellent raw materials, due to their intrinsic characteristics, leading to their use in various products, such as tissue papers. These materials serve multiple purposes, combining cost-effectiveness with increasingly demanding hygiene criteria. The knowledge of the different types of pulp fibers and the results of their modifications by engineering processes contributes to the design of tissue paper materials with the best combination of furnish, for the several types of final products. This work explores the furnish optimization of tissue products, through the development and application of advanced computational tools. A methodology that combines experimental and computational planning was implemented to establish relationships between the key fiber and structure properties, the process steps that modify them, and the structural and functional tissue paper properties. This led to the development of a simulator for furnish optimization and management, the SimTissue. This work presents a significant and innovative contribution in the 3D fiber characterization and modeling, in the application of experimental and computational approaches to evaluate the engineering of fiber and structure modification processes, and in the optimization using advanced computational tools to design soft, resistant, and absorbent tissue materials. The characterization of the fiber dimensions in the paper structure, in the three dimensions (3D), was fundamental to model them, using SEM images methodologies and advanced computational tools for fiber and structure modeling. As a result of this strategy, 3D fiber models were developed, implemented, and used as input variables in computational simulations to predict the structural properties. A representative set of cellulose pulps of industrial interest were selected and characterized, obtained from hardwood and softwood species with different cooking and bleaching processes. The contribution of these pulp fibers with different morphological, chemical and water interaction properties to the tissue properties was accessed through several correlations. Therefore, a planning was implemented from the point of view of engineering fiber and structure modification process variables, influencing the design of tissue paper materials. The pulps were subjected to enzymatic and mechanical treatment, and incorporation of additives in suspension, including micro/nanofibrillated cellulose (MFC/NFC) and biopolymers. All these sets of trials were investigated to quantify their influence, singular or in combination, on the key tissue properties: softness, strength, and absorption. A production methodology of laboratory-made isotropic structures of 20 g/m2 instead of 60 g/m2, with pressing step suppression, was proposed following an adaptation of ISO 5269-1, in order to mimic tissue papers and evaluate these tissue properties. The establishment of relationships between these pulp fibers, the multiple changes resulting from the different processes, and the functional tissue properties was obtained using several computational tools, such as decision/regression trees, multiple linear regressions, artificial neural networks, among others, used as models to support planning and decision-making in industrial production. Therefore, the validation of computational models with these structures was an innovative and irreplaceable milestone to obtain a 3D computational simulator with predictive capacity for tissue structures. This entire process allowed the computational implementation of the SimTissue through the programming of algorithms for the calculation engine and database integration, to be used in specific cases to support industrial furnish management. The design of tissue fibrous materials using these computational tools allowed the development of furnish combinations and process parameters that led to the optimization of each tissue paper. This assisted in the decision of which pulps were most suitable for a given product and which enzymatic and mechanical treatments or additives incorporation enabled an optimized tissue material. By applying this methodology, it was possible to produce tissue structures with maximization of eucalyptus fibers, minimizing the incorporation of softwood pulp fibers, and quantifying the implications of the choices on the final end-use tissue properties. Hence, SimTissue predicts the influence of various types of raw materials used in formulations to produce tissue materials, the influence of modification processes, and the incorporation of additives. The validation of the properties’ prediction was performed with experimental and simulated structures. Each simulation performed can also be compared with formulations with 100% eucalyptus fiber pulps, or with different percentages of other hardwood and softwood fiber pulps, which reflects the ratio used by the tissue paper industry. The present work describes an experimental and computational approach, with the design and development of a predictive capacity tool, with the integration of fundamental variables, to optimize innovative furnish formulations, saving laboratory and industrial resources. This multiscale system, with multiple inputs and multiple outputs, was integrated using computational tools, modeling, and optimization methods. The development of the SimTissue was an innovative milestone to obtain the predictive capability of tissue structures, to support industrial production in furnish management and optimization. The materials design strategy using this computational tool can also be applied to the development of value-added fibrous materials based on eucalyptus fiber and including additives and fibers with micro and nanoscale.