Sur la base de précédents travaux de l’unité INSERM 1148, sur des films à base d’alcool polyvinylique, nous avons implanté et évalué des prothèses de moins de 2mm de diamètre. L’ajout de gelatine in vitro a montré des capacités d’adhérence cellulaires, compatibles avec une endothelialisation in situ, des implants garant, d’une perméabilité à long terme. Notre modèle était le remplacement de 1cm d’aorte sous rénale de rat. Ces implants, ont été utilisées comme modèle d’entrainement basse fidélité à la microchirurgie, avec de meilleurs résultats sur l’acquisition de la technique d’anastomose microchirurgicale, que les tubes en silicone antérieurement utilisé, lors de l’enseignement chez 71 étudiants. Un nouveau moyen d’imagerie pour l’exploration vasculaire par angiographie par résonance magnétique, en temps de vol sans injection chez l’animal, et la première application chez l’homme sont rapportés. Apres avoir présenté notre methode de fabrication par reticulation physique (Lyophilisation Congelation) et chimique (STMP) Cdu PVA, directement sous forme de tubes, nous avons confirmé l’hypothèse que les micro implants à base de PVA associé à la gélatine à hauteur de 1%, a permis d’améliorer la perméabilité par rapport au PVA seul, ou à tout autre ratio de gélatine ; et ce grâce à une endothélisation in situ constatées histologiquement. Les performances biomécaniques de l’implant ont aussi étaient évaluées. Au delà de 2 mois la perméabilité chute de 75% à 50%. Le vieillissement du matériel par son enraidissement, et le relargage de la gélatine pourrait expliquer cette diminution des performances au cours du temps. / Non communiqué

Poly(vinyl alcohol) (PVA) is a polymer used in numerous applications, principally those in which its high water solubility is a desirable asset. However there are also areas where PVA is limited by its inherent solubility (for example some specific environments in the biomedical field). This work has sought to overcome such limits by manipulating the surface of PVA in order to propose various means by which the surface solvent resistance might be increased while maintaining the bulk properties of the polymer. Both chemical and physical modifications have been tried and in each case progress has been made towards insolubilizing a single surface of the polymer when in film form. Grafting various species onto the surface of PVA was successfully performed. It is believed that such species bonded to the PVA via attachment to the hydroxyl groups (though this has not been proven conclusively). The data contained herein has led to the conclusion that the primary factor in reducing solubility this way is the removal of the hydroxyl groups, and not the attachment of specifically highly hydrophobic molecules. Introducing permanent cross-links into the surface region has been attempted via various routes. The data recorded shows promise however the system is far from optimised. The biggest challenge remaining is to optimise the depth of material cross-linked. Some steps have been made towards understanding and controlling this parameter though there is much scope for further investigation. The methods used have built on those used for bulk cross-linking and as such are new for the case of surface specific treatment. An interesting phenomenon in some semi-crystalline polymers reported in recent years is that of surface specific crystallization. This effect has been successfully induced and observed in PVA to produce what is believed to be a highly crystalline surface layer, and crystalline regions of PVA are generally accepted to be more water resistant than amorphous ones. In summary, in this work several surface-specific treatments for PVA have been trialled, providing options for post-film forming modification to reduce the surface water sensitivity whilst retaining the bulk properties of the polymer.

The rheological behavior analysis of Engineered Cementitious Composites (ECC) is key to understand how the different preparation techniques affect the composite mechanical performance. However, the rheological assessment of reinforced materials becomes more complex since fibers usually cause flow disturbances not found in nonreinforced cementitious materials. Besides that, simple workability measurement techniques are not able to fully understand the composite behavior in the fresh state creating the need for more precise techniques to be employed. The main objectives of this study were to evaluate the ECC rheological behavior using different rheometer devices (Vane system and Ball measuring system) and investigate the influence of mixing processes on the fiber homogenization and rheological behavior. Additionally to this, a link between rheological behavior and mechanical performance was investigated. In the end, the ball measuring system revealed to be more efficient than the vane system when evaluating the composite rheological behavior. In addition, the mixing process influenced the rheological behavior of PVA-ECC especially regarding the moment which fibers are added. Fiber addition after mortar mixture improved fibers homogenization and reduced mixing energy by around 8%. Moreover, a correlation between rheological and mechanical properties showed that a 2-times variation in either yield stress or viscosity can lead to a variation of more than 50% in flexural strength without significantly affecting the composite compressive strength. It was also found that the lower the composite yield stress and viscosity the higher was its ultimate strain. To conclude, all those parameters contributed to understand the composite rheological behavior and globally optimize its performance. / Sem resumo

The rheological behavior analysis of Engineered Cementitious Composites (ECC) is key to understand how the different preparation techniques affect the composite mechanical performance. However, the rheological assessment of reinforced materials becomes more complex since fibers usually cause flow disturbances not found in nonreinforced cementitious materials. Besides that, simple workability measurement techniques are not able to fully understand the composite behavior in the fresh state creating the need for more precise techniques to be employed. The main objectives of this study were to evaluate the ECC rheological behavior using different rheometer devices (Vane system and Ball measuring system) and investigate the influence of mixing processes on the fiber homogenization and rheological behavior. Additionally to this, a link between rheological behavior and mechanical performance was investigated. In the end, the ball measuring system revealed to be more efficient than the vane system when evaluating the composite rheological behavior. In addition, the mixing process influenced the rheological behavior of PVA-ECC especially regarding the moment which fibers are added. Fiber addition after mortar mixture improved fibers homogenization and reduced mixing energy by around 8%. Moreover, a correlation between rheological and mechanical properties showed that a 2-times variation in either yield stress or viscosity can lead to a variation of more than 50% in flexural strength without significantly affecting the composite compressive strength. It was also found that the lower the composite yield stress and viscosity the higher was its ultimate strain. To conclude, all those parameters contributed to understand the composite rheological behavior and globally optimize its performance. / Sem resumo

>Magister Scientiae - MSc / Rapid industrialization growth without appropriate emission standards for discharging environmental pollutants had exposed the ecosystem to detrimental effect. Due to their bioaccumulation propensity in organisms, toxicity and non-biodegradable aspect, heavy metal spoliation is currently a significant ecological obligation. Owing to their natural abundance and extensive use, cadmium (Cd) and lead (Pb), among different heavy metals, are the predominant toxic metals. The intrusion of Cd and Pb metal ions into the ecosystem is accomplished by widely accepted methods such as anticorrosive coating of steel, electronic circuit and batteries. / 2023

yes / In order to study the mechanical behaviors of engineered cementitious composites (ECC) reinforced with various types of polyvinyl alcohol (PVA) fibers and different fiber volume fractions after the freeze-thaw cycles, the rapid freeze-thaw method was used to test the mass loss ratios, longitudinal relative dynamic elastic modulus, compressive strength and flexural strength. The results showed that specimens incurred more serious damage with the increasing of freeze-thaw cycles; however their performance would be improved by fiber type and dosage. Mass loss rate of JPA (specimen with 2% volume content of JP fiber) was lower than JPB (specimen with 1% volume content of JP fiber). Furthermore, the mass loss rate of JPB was lower than that of CPB (specimen with 1% volume content of CP fiber). The longitudinal relative dynamic elastic modulus of JPA was higher than that of JPB while the longitudinal relative dynamic elastic modulus of JPB was higher than that of CPB. In addition, the compressive strength and flexural strength decreased with the increasing of freeze-thaw cycles. Mechanical behaviors of specimens with fiber exhibited better strength than specimens without fiber. Based on the SL 211-2006 code for the design of hydraulic structures against ice and freezing action, JPA and JPB specimens are adequate for use in severe cold regions, while specimen CPA and CPB can be used in cold regions, specimen JPC only can be used in warm regions.

Os cimentos de fosfato de cálcio (CFCs) têm atraído grande interesse para uso em ortopedia e odontologia como substitutos para partes danificadas do sistema esquelético, mostrando boa biocompatibilidade e osteointegração, permitindo sua utilização como enxerto ósseo. As características que determinam os CFCs biomateriais atrativos para a reconstituição ou remodelação óssea, são a facilidade de manipulação e moldagem, sem ter de dar forma prévia ao implante, adaptando-se totalmente à forma da cavidade óssea. Diversos estudos, têm mostrado que a adição de aditivos poliméricos tem uma forte influência sobre as propriedades do cimento. A baixa resistência mecânica é o principal obstáculo a uma maior utilização de CFC como material de implante. O objetivo deste trabalho foi avaliar as propriedades de um cimento com base em α-fosfato tricálcico (α -TCP ), adicionado de PVA (poli (álcool vinílico)) (10%, 8%, 6%), hidrogel de PVA (10%,8%,6%) reticulado com ácido cítrico (10%), hidrogel de alginato de sódio (2%) e poliacrilato de amônia (1%), todos em massa, foram adicionados ao pó de α -TCP sintetizado. As amostras foram moldadas e avaliadas quanto à densidade, porosidade, teste ―in vitro‖ (Simulated Body Fluid), fases cristalinas e propriedades mecânicas. Os resultados mostram o aumento das propriedades mecânicas do cimento, quando adicionado destes polímeros. A reticulação dos hidrogéis de PVA com ácido cítrico foi eficiente.O hidrogel de PVA, o hidrogel de alginato de sódio e o poliacrilato de amônia agiram como redutor de líquido. / The calcium phosphate cements (CPCs) have great interest for use in orthopedics and dentistry as replacements for damaged parts of the skeletal system, showing good biocompatibility and osseointegration, allowing its use as a bone graft. The characteristics that determine CPCs attractive biomaterials for bone remodeling or rebuilding, is ease of handling and molding, without having to shape prior to implantation, adapting itself fully to the shape of the bone cavity. Several studies in literature have shown that the addition of polymeric additives has a strong influence on the mechanical properties of cement. The low mechanical strength is the main impediment to a broader use of calcium phosphate bone cement as implant material. The aim of this work was evaluate the strength of a CPC based on α-tricalcium phosphate, with polymeric additions. CPC was synthesized and PVA (poli (vinyl alcohol)) (10%, 8%, 6%), sodium alginate hydrogel (2%) and ammonium polyacrylate (1%), all by weight, were added to the powder. Specimens were molded and evaluated for density, porosity, in vitro test (Simulated Body Fluid), crystalline phases and mechanical properties. The results show the increase of the mechanical properties of cement when added of polymeric additives. The crosslinking of PVA hydrogels with citric acid was effective. The PVA hydrogel, the hydrogel sodium alginate and ammonium polyacrylate acted as a reducing liquid.

Os cimentos de fosfato de cálcio (CFCs) têm atraído grande interesse para uso em ortopedia e odontologia como substitutos para partes danificadas do sistema esquelético, mostrando boa biocompatibilidade e osteointegração, permitindo sua utilização como enxerto ósseo. As características que determinam os CFCs biomateriais atrativos para a reconstituição ou remodelação óssea, são a facilidade de manipulação e moldagem, sem ter de dar forma prévia ao implante, adaptando-se totalmente à forma da cavidade óssea. Diversos estudos, têm mostrado que a adição de aditivos poliméricos tem uma forte influência sobre as propriedades do cimento. A baixa resistência mecânica é o principal obstáculo a uma maior utilização de CFC como material de implante. O objetivo deste trabalho foi avaliar as propriedades de um cimento com base em α-fosfato tricálcico (α -TCP ), adicionado de PVA (poli (álcool vinílico)) (10%, 8%, 6%), hidrogel de PVA (10%,8%,6%) reticulado com ácido cítrico (10%), hidrogel de alginato de sódio (2%) e poliacrilato de amônia (1%), todos em massa, foram adicionados ao pó de α -TCP sintetizado. As amostras foram moldadas e avaliadas quanto à densidade, porosidade, teste ―in vitro‖ (Simulated Body Fluid), fases cristalinas e propriedades mecânicas. Os resultados mostram o aumento das propriedades mecânicas do cimento, quando adicionado destes polímeros. A reticulação dos hidrogéis de PVA com ácido cítrico foi eficiente.O hidrogel de PVA, o hidrogel de alginato de sódio e o poliacrilato de amônia agiram como redutor de líquido. / The calcium phosphate cements (CPCs) have great interest for use in orthopedics and dentistry as replacements for damaged parts of the skeletal system, showing good biocompatibility and osseointegration, allowing its use as a bone graft. The characteristics that determine CPCs attractive biomaterials for bone remodeling or rebuilding, is ease of handling and molding, without having to shape prior to implantation, adapting itself fully to the shape of the bone cavity. Several studies in literature have shown that the addition of polymeric additives has a strong influence on the mechanical properties of cement. The low mechanical strength is the main impediment to a broader use of calcium phosphate bone cement as implant material. The aim of this work was evaluate the strength of a CPC based on α-tricalcium phosphate, with polymeric additions. CPC was synthesized and PVA (poli (vinyl alcohol)) (10%, 8%, 6%), sodium alginate hydrogel (2%) and ammonium polyacrylate (1%), all by weight, were added to the powder. Specimens were molded and evaluated for density, porosity, in vitro test (Simulated Body Fluid), crystalline phases and mechanical properties. The results show the increase of the mechanical properties of cement when added of polymeric additives. The crosslinking of PVA hydrogels with citric acid was effective. The PVA hydrogel, the hydrogel sodium alginate and ammonium polyacrylate acted as a reducing liquid.

Os cimentos de fosfato de cálcio (CFCs) têm atraído grande interesse para uso em ortopedia e odontologia como substitutos para partes danificadas do sistema esquelético, mostrando boa biocompatibilidade e osteointegração, permitindo sua utilização como enxerto ósseo. As características que determinam os CFCs biomateriais atrativos para a reconstituição ou remodelação óssea, são a facilidade de manipulação e moldagem, sem ter de dar forma prévia ao implante, adaptando-se totalmente à forma da cavidade óssea. Diversos estudos, têm mostrado que a adição de aditivos poliméricos tem uma forte influência sobre as propriedades do cimento. A baixa resistência mecânica é o principal obstáculo a uma maior utilização de CFC como material de implante. O objetivo deste trabalho foi avaliar as propriedades de um cimento com base em α-fosfato tricálcico (α -TCP ), adicionado de PVA (poli (álcool vinílico)) (10%, 8%, 6%), hidrogel de PVA (10%,8%,6%) reticulado com ácido cítrico (10%), hidrogel de alginato de sódio (2%) e poliacrilato de amônia (1%), todos em massa, foram adicionados ao pó de α -TCP sintetizado. As amostras foram moldadas e avaliadas quanto à densidade, porosidade, teste ―in vitro‖ (Simulated Body Fluid), fases cristalinas e propriedades mecânicas. Os resultados mostram o aumento das propriedades mecânicas do cimento, quando adicionado destes polímeros. A reticulação dos hidrogéis de PVA com ácido cítrico foi eficiente.O hidrogel de PVA, o hidrogel de alginato de sódio e o poliacrilato de amônia agiram como redutor de líquido. / The calcium phosphate cements (CPCs) have great interest for use in orthopedics and dentistry as replacements for damaged parts of the skeletal system, showing good biocompatibility and osseointegration, allowing its use as a bone graft. The characteristics that determine CPCs attractive biomaterials for bone remodeling or rebuilding, is ease of handling and molding, without having to shape prior to implantation, adapting itself fully to the shape of the bone cavity. Several studies in literature have shown that the addition of polymeric additives has a strong influence on the mechanical properties of cement. The low mechanical strength is the main impediment to a broader use of calcium phosphate bone cement as implant material. The aim of this work was evaluate the strength of a CPC based on α-tricalcium phosphate, with polymeric additions. CPC was synthesized and PVA (poli (vinyl alcohol)) (10%, 8%, 6%), sodium alginate hydrogel (2%) and ammonium polyacrylate (1%), all by weight, were added to the powder. Specimens were molded and evaluated for density, porosity, in vitro test (Simulated Body Fluid), crystalline phases and mechanical properties. The results show the increase of the mechanical properties of cement when added of polymeric additives. The crosslinking of PVA hydrogels with citric acid was effective. The PVA hydrogel, the hydrogel sodium alginate and ammonium polyacrylate acted as a reducing liquid.

A artrose, também chamada de osteoartrose ou osteoartrite (OA), é a terceira doença de maior incidência no Mundo. Nesse trabalho, buscou-se criar uma lesão osteocartilaginosa em joelhos de ratos Wistar machos com seis meses de vida, objetivando constituir um modelo animal para estudo da OA humana e, a partir desse modelo, avaliar biomateriais de forma isolada ou associados entre si e avaliados quanto à sua segurança biológica e potencial de reparação tecidual. Além disto, foi analisado o efeito reparador de células-tronco mesenquimais da polpa do dente de leite humano (MSC) isoladamente e em associação com o biomaterial formado por: Titânio + Poli Vinil Álcool + Ac. Hialurônico, nesse estudo denominado de TRIGEL (TRG). O Ac. Hialurônico (HA), por suas propriedades visco elásticas, o pó de Titânio (Ti), devido às suas propriedades biológicas únicas de ostoeintegração e o polímero Poli Vinil Álcool (PVA), com suas propriedades hidrofílicas, promovendo a formação do Hidrogel, os quais associados entre si formam um compósito, o TRG, que foi aplicado sobre uma lesão padrão no joelho da pata pélvica direita de ratos Wistar machos de seis meses de idade. Para a obtenção da lesão padrão, os animais foram divididos em três grupos de cincoanimais e cada grupo foi submetido a uma intervenção cirúrgica em seus joelhos direitos, utilizando três técnicas cirúrgicas diferentes, a saber: Grupo (I): Remoção cirúrgica dos meniscos medial e lateral mais perfuração do platô tibial seguido da aspiração da medula óssea através dessa perfuração por meio de seringa e agulha. Grupo (II): Remoção dos meniscos mais perfuração, sem aspiração, Grupo (III): Apenas a perfuração. Todos os animais foram autopsiados após 30 dias. Os joelhos dos quinze animais que constituíam os três grupos foram devidamente catalogados e enviados para a empresa Histotech, para a confecção das lâminas, tendo sido eleito, por análise histológica, o Grupo (I), por demonstrar menor reparo tecidual espontâneo. Em tese, o TRG teria as seguintes propriedades: Uma fonte de reparação tecidual (visco terapia) dada pelo HA e a capacidade amortecedora e carreadora de células-tronco do polímero PVA, que se hidrata, formando o hidrogel. O Ti, pela sua propriedade de osteointegração formaria um tampão sobre as áreas de matriz óssea exposta o que possibilitaria o afluxo de novos condrócitos, que também pode ocorrer pela ação das células-tronco. Livrar a superfície articular das áreas com exposição da matriz óssea é fundamental para o bloqueio das proteases que perpetuam a fisiopatologia da OA. Após tratamento estatístico dos diversos ensaios, utilizando-se os diversos biomateriais no tratamento da lesão, o TRG foi o biomaterial que apresentou o melhor resultado de força entre os grupos. No estudo histológico, foi evidenciada a presença de tecido cartilaginoso supra- lesional, o que só ocorreu nos animais dos grupos que receberam: apenas TRG, TRG associado com células-tronco e aquele que recebeu apenas MSCs. No entanto, mais estudos, com animais de maior porte e mais velhos, devem ser realizados para melhor analisar a segurança e o potencial terapêutico do compósito Trigel. / Osteoarthritis, or osteoarthritis (OA) is the third most debilitating disease in the world. In this study, we attempted to create an osteocartilaginous lesion in the knees of six months old male Wistar rats, aiming to constitute an animal model for the study of human OA and to use this model to evaluate the therapeutic potential of biomaterials, which are already well known for their biocompatibility properties in the clinical practice. The biomaterials were used in isolation or associated with each other and then evaluated for their biological safety and tissue repair capacity. Mesenchymal stem cells, obtained from human dental pulp from deciduous teeth (MSC) were evaluated alone and in association with the biomaterial formed by: Titanium + Poly Vinyl Alcohol + Ac. Hyaluronic, here called TRIGEL (TRG). Due to its visco-elastic properties, the Ti powder, due to its unique biological properties of ostointegration and the polymer PVA, with its hydrophylic properties, forming a hydrogel, were associated to form the composite named TRIGEL, (TRG), which was applied to a standard knee injury of the right hind leg of male Wistar rats. In order to elect the standard lesion, the animals were divided into three groups with five animals each and each group underwent a surgical intervention in their right knees, with three different surgical techniques being applied, namely: Group (1): Surgical removal ofmedial and lateral meniscus plus perforation of the tibial plateau, followed by aspiration of the bone marrow through this perforation using syringe and needle. Group (2): Removal of the meniscus plus perforation, without aspiration, Group (3): Drilling only. All groups were autopsied 30 days after the procedure and all groups were autopsied at 30 days post-procedure. The knees of the 15 animals that constituted the three groups were analyzed histologically and Group (1) (meniscus removed, perforated and aspirated), was elected as the standard lesion since it demonstrated less spontaneous tissue repair. TRG has the following properties: HA is used as a source of tissue repair (visco therapy) and hydration of the polymer; PVA, forms a hydrogel\", with damping action and as a stem cells carrier, whereas Ti was used due to its ósseo-integration, which would allow coating of the exposed bone matrix and this intra-osseous osteo-integration response would form an intercalating buffer. The healthy cartilage surfaces around this structural buffer would allow the reception of new chondrocytes or the action of the cells on TRG properties. Freeing the articular surface of the areas with bone matrix exposure is critical for blocking the proteases that perpetuate the pathophysiology of OA. In the various biomaterial tests in the treatment of the standard lesions, TRG was statistically shown to be the one that better mimicked the non-injured group. The histological study demonstrated the presence of a supra-lesional cartilagenous tissue, which only occurred in the groups which received: only TRG, mesenchymal stem cells associated with TRG and that which received only MSCs. However, further studies with larger and older animals should be pursued to better assess the safety and therapeutic potential of the Trigel composite.