L'application des biomatériaux est de plus en plus élargie. Le progrès médical suggère l'utilisation des biomatériaux (verres bioactifs, apatites,..) en tant qu'implants selon le besoin de l'organisme. L'objectif de notre travail est de mettre en évidence l'influence biologique des molécules organiques (bisphosphonates, biopolymères et antibiotiques) incorporés dans des matrices de verres bioactifs. De même, notre étude vise à optimiser les meilleures techniques de synthèse et d'association des verres bioactifs à ces molécules. La détoxification des rats mâles de souche « Wistar » exposés au chlorure de nickel par une apatite synthétique a aussi fait l'objet de ce travail. Suite à une perte osseuse provoquée, nous avons démontré que l'utilisation des antibiotiques associés à des verres bioactifs en tant qu'implants osseux, chez des rattes ovariectomisées, permet d'éliminer certains effets indésirables par voie systémique. Ceci a été mis en évidence par l'évaluation des paramètres biochimiques et histologiques du foie et du rein. Aucune variation significative en comparaison avec ceux du témoin négatif n'a été révélée. L'étude in vitro a montré d'une part que l'introduction du Chitosan et surtout de l'antibiotique dans la matrice vitreuse font augmenter l'activité antibactérienne in vitro. Cette étude in vitro a montré d'autre part que la Ciprofloxacine induit un effet néfaste sur les cellules ostéoblastiques et endothéliales. Cet effet est local lorsqu'il s'agit des expérimentations in vivo. Ceci est mis en évidence lors des évaluations du statut oxydant. Les marqueurs du remodelage osseux, l'histologie de l'os et les paramètres physico-chimiques montrent l'effet retardateur de cet antibiotique sur la dissolution de l'implant et par conséquent sur son ossification. La synthèse par le procédé de sol-gel provoque une bioactivité plus importante que celle obtenue par fusion. La bioactivité des verres bioactifs étudiés diffère selon la molécule introduite. Celle-ci est réduite dans le cas de l'association du Clodronate et de Ciprofloxacine in vitro et in vivo. Alors que, le Polyvinyl Alcohol et surtout le Chitosan font modifier la cinétique de cette bioactivité in vivo. Concernant l'hydroxyapatite, nous avons essayé d'explorer son effet détoxifiant chez des rats reçevant le chlorure de nickel. Nos résultats ont montré que le nickel induit un stress oxydant au niveau du foie, du rein, de la rate et du culot érythrocytaire. Des troubles physiologiques ont été observés chez les rats exposés au nickel. Cependant, l'implantation de l'hydroxyapatite protège les rats intoxiqués par le nickel contre ses effets toxiques en diminuant l'état du stress. Le biomatériau utilisé s'avère efficace pour corriger l'équilibre ferrique et phosphocalcique, protéger les fonctions rénale et hépatique, abaisser le taux du nickel osseux et corriger l'anémie. / The application of biomaterials is increasingly widened. Medical progress suggest the use of biomaterials (bioactive glasses, apatites,..) as implants according to the need of the body. The aim of our work is to highlight the biological influence of organic molecules (bisphosphonates, biopolymers and antibiotics) incorporated into matrix of bioactive glasses. Similarly, our study aims to optimize the best synthesis and combination technique of bioactive glasses to these molecules. The detoxification of male rats strain "Wistar" exposed to nickel chloride by a synthetic apatite also has been the object of this work. Following the bone loss induced, we have demonstrated that the use of antibiotics associated with bioactive glass as bone implants, in ovariectomised rats, eliminates some adverse effects systemic. This has been highlighted by the evaluation of biochemical and histological parameters of liver and kidney. Any significant changes in comparison with those of the negative control was revealed. The in vitro study showed in the one hand that the introduction of Chitosan and especially of the antibiotic in the glass matrix can increase antibacterial activity. This in vitro study showed in the other hand that the Ciprofloxacin induces a negative effect on osteoblastic and endothelial cells. This effect is local when it has been an in vivo experiments. This is highlighted by the oxidative status evaluation. Markers of bone turnover, bone histology and physicochemical parameters show the retarding effect of this antibiotic on the dissolution of the implant and consequently on its bone formation. Synthesis by sol-gel method causes a more important bioactivity than melting. The bioactivity of elaborated bioactives glasses will differ depending on the molecule introduced. It is reduced in the case of combination of Clodronate and Ciprofloxacin in vitro and in vivo. While, Polyvinyl Alcohol and especially Chitosan modify the kinetic of the bioactivity in vivo. Concerning the hydroxyapatite, we tried to explore its detoxifying effect in rats receiving nickel chloride. Our results showed that nickel induces an oxidative stress in the liver, kidney, spleen and red cell pellet. Physiological disorders were observed in rats exposed to nickel. However, implantation of hydroxyapatite protects rats intoxicated by nickel against its toxic effects by decreasing the stress status. The used biomaterial is effective to correct ferric phosphate balance, protect kidney and liver function, reduce level of bone nickel and correct anemia.

Les phosphates de calcium sont les céramiques les plus utilisées dans la régénération osseuse grâce à leur biocompatibilité et leur bonne résorption. Pourtant, leur performance peut être améliorée s'ils sont associés à des facteurs de croissance. Afin de contrôler le relargage des facteurs de croissance, l'objectif de la thèse a été de synthétiser des phosphates de calcium avec une mésoporosité contrôlée. Ce travail représente la première association des phosphates de calcium mésoporeux avec les facteurs de croissance TGF et VEGF.Pour obtenir des phosphates de calcium mésoporeux, des nouvelles techniques de réplique ont été mises en place : L'hydroxyapatite est synthétisée dans la porosité des templates siliciques ou carbonés par infiltration de précurseurs en solution aqueuse. L'élimination de la matrice s'effectue par dissolution chimique par de la soude dans le cas du template silicique et par oxydation sélective sous air dans le cas du template carboné. Six céramiques ont été choisies pour une analyse de leurs capacités d'adsorption et de relargage de protéines. Dans un premier temps, un protocole est mis en place en utilisant des protéines modèles, la BSA et le Cytochrome Cavant d'utiliser les facteurs de croissance TGF et VEGF. Ces travaux ont permis de déterminer les poudres les plus efficaces en terme d'adsorption et de relargage contrôlé de ces facteurs de croissance. / Calcium phosphates are the most frequently used ceramics for bone regeneration due to their biocompatibility and favorable resorption properties. Their performance can however be improved if they are associated to growth factors. In order to control the release of growth factors, we have inted to synthesize calcium phosphates with controlled mesoporosity. This thesis represents the first work that combines mesoporous calcium phosphates with the growth factors TGF and VEGF. To obtain hydroxyapatite with controlled mesoporosity, we propose new synthesis pathways: the hydroxyapatite is synthesized inside the porosity of silica or carbon templates by infiltration of aqueous precursor solutions. The template is eliminated by chemical etching with NaOH (silica template) or by selective oxidation (carbon template). Six ceramics have been chosen for the analysis of their protein adsorption and release properties. First, the experimental protocol is defined using the model proteins BSA and Cytochrom C. Then, the growth factors TGF and VEGF have been used. By this study, we were able to determine which samples were the most efficient in terms of protein adsorption and release.

Surfaces and interfaces are of fundamental importance from the nucleation to growth of crystals formed under different conditions such as vapor phase, liquid phase including biomineralisation conditions. Recently there is lot of interest in controlling the shape of nanoparticles during the synthesis due to their excellent shape dependent properties. Understanding the role of surfaces and interfaces is vital for such shapecontrolled synthesis of nanomaterials. On the surface, coordination number, structure, density and composition are different from that of bulk and hence the properties are completely different in the surfaces and interfaces of any crystalline material. Especially when the length scale become nanoscale, the surface and interface play a dominant important role and leads to several new and interesting phenomena. In this dissertation, the role of surfaces and interfaces on the synthesis and the properties of inorganic functional nanostructures have been studied. The work primarily relies on basic chemistry to synthesize nanostructures that brings the importance of surfaces/interfaces into the picture. Though several basic characterization techniques have been used, electron microscopy has been the emphasis and has been used extensively through the work to probe and explore the materials for characterizing the structures over a variety of length scales. The entire thesis based on the results and findings obtained from the present investigation are organized as follows: Chapter1 gives a general introduction to the surfaces and interfaces to create a background for the investigation. This emphasizes the role of surfaces and interfaces in several aspects starting from nucleation, growth to the properties of inorganic crystals. It gives some exposure in to the different type of surface phenomenon which is common in nanoscale materials. Chapter 2 deals with the materials and methods which essentially gives the information about the materials used for the synthesis and the techniques utilized to characterize the materials chosen for the investigation. Chapter 3 deals with predicting the morphology of 2D nanostructures by combining the crystal growth theory into chemical thermodynamics. Morphology diagrams have been developed for Au, Ag, Pt and Pd to predict conditions under which two-dimensional nanostructures form as a result of a chemical reaction. In addition, it provides the general understanding of shape control in 2D nanostructures with atomistic mechanism. The validity of the morphology diagram has been tested for various noble metals by carrying out critical experiments. As a result, 2D nanostructures of metals projecting the lowest energy facet resulted in a complete novel way in the absence of any capping/reducing agents. Chapter 4 deals with predicting the formation of 2D nanostructures of inorganic crystals formed as a result of precipitation reaction. Morphology diagram has been developed for the case of hydroxyapatite, an inorganic part of the human bone. This answers some of the long standing question related to the shape of the HA crystals formed in the bone by biomineralisation. The generality of the method has been tested to few other inorganic crystals such as CaCO3, ZnO and CuO formed through precipitation reaction. The key finding of the above two chapter is that the low driving force of the chemical reactions results in two dimensional nanostructures. On contrary, high chemical driving force combined with the optimum zeta potential results in porous aggregate of nanoparticles. Chapter 5 discusses the formation of porous clusters of metals and ceramics at specific conditions. The mechanism behind the formation of monodisperse aggregates are investigated based on the interaction energies of nanoparticles in aqueous medium. This chapter reveals the role of surface charge and the surface energy in controlling the stability of nanoparticles in aqueous medium. In addition, it provides the simple methodology to produce well controlled porous clusters by exploiting the competition between surface charge and surface energy during the aggregation. The application of the porous clusters of Pt has been tested for methanol oxidation which is essential for fuel cell applications. Chapter 6 deals with the development of porous biphasic scaffolds through the morphology transition of nanorods. Rod shape is not stable when subjected to high temperature due to instability and spherodisation takes place to minimize the surface energy. Here in this chapter, by exploiting spherodisation along with the phase transition, highly interconnected porous structure of hydroxyapatite and tricalcium phosphate is achieved. Combined with the morphology transition, by adding naphthalene as a template, the possibility of achieving hierarchical porous structure also presented. The mechanical strength of the biphasic porous scaffold has been tested by microindentation. Mechanical properties of apatite are generally poor and there are lots of efforts to improve the mechanical properties apatite by the composite approach. Chapter 7 deals with the HA-Alumina and HA-TCP composites. In spite of much attention given to the mechanical properties of the composites, the interfacial phenomenon that takes place between the components of the nanocomposite has not been studied in detail. In the present study, interfacial reactions in hydroxyapatite-alumina nanocomposites have been investigated and new reaction mechanism also proposed. The degradation of densification process has been observed for the HATCP composites due to the creation of porous interface between HA crystals and TCP matrix. Mechanical properties of these two composites have been studied using microindentation. The mechanical properties of HA and TCP single crystals are important for developing the biphasic composites with reliable mechanical properties. Chapter8deals with the mechanical behavior of hydroxyapatite and tricalcium phosphate single crystals. The mechanical properties of HA and TCP have been studied by performing nanoand microindentation on specific crystallographic facets. In case of hydroxyapatite, the anisotropy in mechanical properties has been explored by performing indentation on its prism and basal planes. Nanoscale plasticity is observed in both HA and TCP crystals which arise due to the easy movement of surface atoms with lesser coordination compared to the bulk. Nanoindentation has been performed in the calciumdeficient HA platelets provides important clues about the role of calcium deficiency on the mechanical behavior of bone and has implications for the properties of osteoporotic bones.

Pour le comblement d'une perte de tissu, la greffe reste une méthode usitée en chirurgie osseuse mais une lacune importante conduit à l'emploi de matériaux artificiels. Alternative aux implants métalliques, les substituts osseux biocéramiques ont une efficacité insuffisante dans de nombreuses indications : problème d'intégration d'un volume important, résistance inadéquate à long terme, faible bioréactivité. Doper ces biocéramiques est une voie intéressante mais nombre de dopants ont abouti à des effets cytotoxiques voire à la dégradation des propriétés mécaniques. Le magnésium a été étudié comme dopant de l'hydroxyapatite pour des faibles teneurs, apportant des améliorations sans affecter la biocompatibilité. Cependant, les fortes teneurs et l'optimisation de la synthèse d'une biocéramique dopée ont été peu étudiées. Nous avons étudié et optimisé la synthèse d’hydroxyapatite par la méthode de précipitation aqueuse pour un dopage au magnésium de 1, 2, 5 et 10 % en masse. Caractérisations physicochimiques (DRX, MEB, densité), biologiques (cytotoxicité) et mécaniques (microdureté, élasticité) ont été menées (poudres ou pastilles frittées ou non). Nous avons montré l'apparition de TCP à partir de 2 % Mg, la densité des échantillons diminuant quand la teneur croît. Le dopage accroît la microdureté et le module d’Young. Aucune cytotoxicité n'a été révélée mais une importante baisse d’activité cellulaire a été remarquée pour 10 % de magnésium. Une légère augmentation a été observée pour 1 %. L'aptitude à la mise en forme a été appréciée via le coulage d'une réplique d'un implant intervertébral. Le dopage d'HA à 1 % Mg s'avère être à tout point de vue le compromis optimal. / For the filling of a loss of tissue, the graft is a current process in bone surgery, but a significant deficiency leads to the use of artificial materials. Alternative to metallic implants, bone substitutes bioceramics have insufficient efficacy in many indications: problem of integrating a large volume, inadequate long-term resistance, low bioreactivity. Doping these bioceramics is an interesting way but many of dopants have conducted to cytotoxic effects or to the degradation of mechanical properties. Magnesium has been studied as a dopant of hydroxyapatite for low contents, improving thebioceramic without affecting its biocompatibility. However, high contents and the optimization of the synthesis of such a doped bioceramic have been little studied. We investigated and optimized the synthesis of hydroxyapatite by the aqueousprecipitation process for magnesium doping of 1, 2, 5 and 10 wt%. Physico-chemical (XRD, SEM, density), biological (cytotoxicity) and mechanical (microhardness, elasticity) characterizations were conducted (on powders or pellets sintered or not). We have shown the occurrence of TCP from 2% Mg, the density of samples decreasing when the content grows. The doping increases the microhardness and the Young’s modulus. No cytotoxicity was revealed but a significant decrease in cellular activity was noted for 10% magnesium. A slight increase was observed for 1%. The ability to form an implant was assessed via the slip casting of a replica of an intervertebral implant. Doping HA to 1% Mg was found to be at any point of view the optimum composition.

Les structures poreuses tridimensionnelles fonctionnelles possèdent un fort potentiel dans de nombreuses applications biomédicales. Nous avons ainsi orienté nos travaux vers l'élaboration de nouveaux matériaux capables de répondre à plusieurs critères pour l'ingénierie tissulaire osseuse. Du fait de leur biodisponibilité, leur biocompatibilité et leur biodégradabilité, les poly(3-hydroxyalcanoate)s (PHAs) présentent des propriétés particulièrement adaptées pour ce type d'application. Dans un premier temps, nous avons développé de nouvelles stratégies contrôlées, rapides et aisées, de synthèse de copolymères à blocs à base de PHAs ainsi que de production d'oligoesters par activation sous micro-ondes. Par ailleurs, l'absence d'effet « non-thermique » des micro-ondes sur la polymérisation par ouverture de cycles du D,L-lactide a également été démontrée grâce à une investigation systématique. Dans un second temps, l'élaboration de divers matériaux tridimensionnels nanofibreux par électrofilage (« electrospinning ») a été réalisée afin de fabriquer des structures à base de PHAs de différentes morphologies avec la formation de fibres dans une large gamme de diamètres ou encore avec des topographies de surface contrôlées (nanopores ou rainures). Plusieurs stratégies de fonctionnalisation superficielle ont été également mises au point telles que le dépôt de nanoparticules d'hydroxyapatite selon un procédé original couplant les techniques de l' « electrospinning » et de l' « electrospraying », ou encore le « co-electrospinning » de la gélatine. De nouvelles approches de couplage covalent de molécules en surface des fibres de PHAs par chimie « click » ou par ouverture de fonctions époxyde préalablement introduites ont également été développées. Enfin, des investigations biologiques in vitro ont permis de mettre en lumière les potentialités de ces nouveaux matériaux nanofibreux comme supports de culture cellulaire à travers l'évaluation de l'adhérence, la prolifération et la différentiation de cellules souches mésenchymateuses humaines (hMSCs) pluripotentes vers un phénotype ostéoblastique / Functional three-dimensional porous scaffolds possess a high potential in many biomedical applications. We have thus oriented our work toward the elaboration of new materials able to meet several criteria for bone tissue engineering. Due to their renewability, their biocompatibility, and their biodegradability, poly(3-hydroxyalkanoate)s (PHAs) exhibit properties particularly suitable for this type of application. First, we have developed novel controlled strategies that are rapid and straightforward for the synthesis of PHA-based block copolymers as well as for the production of oligoesters upon microwave activation. Moreover, the absence of “non-thermal” microwave effect in the ring-opening polymerization of D,L-lactide was also demonstrated through a systematic investigation. Second, the elaboration of miscellaneous three-dimensional nanofibrous materials by electrospinning has been performed to produce PHA-based frameworks with different morphologies through the formation of fibers in a wide range of diameters or with controlled surface topography (nanopores or channels). Several strategies for surface functionalization have also been implemented, such as the deposition of hydroxyapatite nanoparticles by an original combination of the electrospinning and electrospraying techniques or by the co-electrospinning of gelatin. New approaches toward covalent coupling of molecules on the PHA fiber surface by “click” chemistry or by ring-opening of previously introduced epoxide groups have also been developed. Lastly, in-vitro biological investigations have highlighted the potential of these new nanofibrous materials as cell culture supports through the evaluation of the adhesion, proliferation, and differentiation of pluripotent human mesenchymal stem cells (hMSCs) toward an osteoblastic phenotype

Compte tenu de leur bioactivité et de leur ostéoconduction, les revêtements d’hydroxyapatite (HA) favorisent le développement de tissu osseux et contribuent à l’adhérence et à la prolifération des cellules osseuses tout en préservant l’intégrité mécanique du dispositif métallique de l’implant. Toutefois, des signes de résorption de cette couche ont été constatés et l’introduction du procédé de projection plasma pour la réalisation de dépôts d’HA a donné lieu à plusieurs controverses. Certaines études ont montré que les dépôts d’HA par projection plasma présentent une mauvaise adhérence sur le titane, une dégradation et écaillage avec le temps. Ce phénomène est attribuable à la décomposition de l'HA au cours de la projection et à l'existence de phases secondaires cristallisées ou amorphes qui fragilisent le dépôt. A l’heure actuelle, les recherches de nouvelles apatites thermiquement plus stables se développent. Ainsi des dépôts à base de fluorapatite ou de fluorhydroxyapatite fournissent des dépôts plus stables et plus adhérents. Il existe d’autres formes d’apatites comme la chlorapatite (ClA) qui fond sans se décomposer ce qui permettrait d’éviter la formation des phases étrangères qui provoquent l’écaillage du dépôt. Ce travail porte sur la synthèse et la caractérisation de phosphates de calcium apatitiques destinés au recouvrement de prothèses ostéoarticulaires et/ou d’implants dentaires métalliques. L’élaboration des poudres d’apatite a été réalisée par réaction solide-solide, en solution aqueuse ou en sel fondu. Plusieurs apatites ont été étudiées : la fluorapatite, la fluorhydroxyapatite, la chlorapatite et l’apatite calcostrontique. On obtient des poudres pures, bien cristallisées et stoechiométriques. Nous avons ensuite étudié la stabilité thermique des poudres d’apatite par analyse thermogravimétrique. La stabilité thermique de la ClA et sa fusion sans décomposition permettent d’obtenir des dépôts sans phases secondaires avec un taux de cristallinité élevé. Parmi toutes les poudres étudiées, nous avons choisi de sélectionner la chlorapatite pour la suite de l’étude ainsi que l’hydroxyapatite comme référence. La poudre de ClA est déposée sur un substrat en titane via une mini-torche plasma mobile à basse énergie, conçue pour les implants dentaires ou orthopédiques de petites tailles et de géométries complexes. La projection par la mini-torche plasma permet de réaliser des dépôts fins et adhérents. Les propriétés structurales et microstructurales des dépôts de ClA et d’HA effectués dans les mêmes conditions ont été évaluées par diffraction des rayons X, spectroscopies FTIR et Raman. L’analyse des revêtements de ClA et d’HA par diffraction des rayons X atteste de la présence d’une seule phase cristalline. Néanmoins, le rapport de cristallinité des dépôts de ClA est largement supérieur à celui des dépôts d’HA, pour lesquels le rapport de cristallinité est supérieur à la norme requise. Ce résultat est du à la stabilité thermique de la ClA par rapport à l’HA. Les spectroscopies FTIR et Raman montrent la présence d’un faible taux de phase amorphe et d’oxyapatite. Nous avons également développé une nouvelle méthode semi-quantitative par cartographie Raman permettant de déterminer l’homogéneité de composition du dépôt. Enfin, nous avons montré que l’adhérence des dépôts de ClA au substrat déterminée suivant la norme ASTM C633 est équivalente à celle de l’HA. La réponse biologique des dépôts a été étudiée in vitro avec des cellules pré-ostéoblastes humaines sur les deux compositions ClA et HA. Les tests montrent que quelle que soit la composition du dépôt, la prolifération cellulaire augmente au cours du temps d’incubation. Une étude in vivo a été menée sur un modèle animal ovin en site fémur et humérus pour des durées de 2 et 6 mois afin d’évaluer le potentiel ostéoconducteur des dépôts d’HA et de ClA. Aucune réaction inflammatoire n’a été observée et l’interprétation des résultats d’analyses histologiques et physico-chimiques est en cours. / Plasma-sprayed hydroxyapatite (HA) has been shown to enhance bone apposition as compared with uncoated metal implants. In spite of their good clinical performances, implant bio-integration is still limited due to the poor adhesion of HA-coating on the titanium surface and the decomposition of HA into several foreign phases during plasma spray. The plasmaspray process was thus considered not to be optimum for HA coatings. To circumvent these disadvantages, other types of calcium phosphates have been proposed to replace HA, such as tricalcium phosphate or biphasic calcium phosphate with little improvement. Chlorapatite (ClA) however has never been tested despite its ability to melt without decomposition which could be a decisive advantage to avoid apatite decomposition and could increase coating crystallinity. This work concern the synthesis and the characterization of apatitic calcium phosphate as coating for endoprostheses and dental implants. The syntheses of the different apatite powders were performed by solid-solid reaction, in aqueous solution or by molten salt reaction. Several apatites were studied: fluorapatite, fluorhydroxyapatite, chlorapatite and strontium substituted apatite. The as-synthesized powders are pure, well crystallized and stoechiometric. The thermal properties of apatite powders were compared using thermogravimetric analysis. The thermal stability of ClA and its melting without decomposition allows to obtain deposits with no secondary phases and with a degree of crystallinity close to 100 %. We have therefore chosen ClA and HA as feedstock powders to achieve coatings. The as-synthesized ClA powder was deposited on a titanium substrate using a novel low energy plasma mini-gun characterized by a low power range (<13 kW) and portability allowing in-situ coating deposition designed for dental and orthopedic small implants with complex geometry. The plasma spray with the mini-gun gives thin and adherent coatings. It also provides economic benefits such as low energy and a higher yield of feedstock powder than conventional gun. The structural and microstructural properties of ClA and HA coatings performed under the same conditions were evaluated by X-ray diffraction, Raman and infrared spectroscopy. X-ray diffraction analyses on the ClA and HA coatings indicate the presence of crystalline apatite as the only crystalline phase. However, the crystallinity ratio of ClA coatings was much higher than that of HA coatings but superior to the required standard in both cases. This difference is due to the thermal stability of ClA powder. IR and Raman spectroscopy shows the presence of low levels of amorphous phase and oxyapatite. We have also developed a new semiquantitative method by Raman imaging in order to determine coating homogeneity. The mechanical properties of coatings were determined according to the standard test measurements ASTM C633. The adhesion of ClA coatings to the substrate is equivalent to HA coatings. The biological response of the coatings was studied in vitro with human preosteoblast cells on both ClA and HA coatings. Tests show that wathever the composition of coating, cell proliferation increases with time of incubation. The in vivo osteoconductive properties of coatings were studied in femur and humerus sites of an ovine animal model during 2 and 6 months. No inflammatory reaction has been observed and the interpretation of histological and physico-chemical results is in progress.

Le frittage micro-ondes est connu pour être une technique de frittage prometteuse. En effet, ce procédé présente comme avantages une réduction de la durée des traitements thermiques et un gain énergétique important par rapport aux procédés conventionnels. D'année en année, le frittage dans un environnement micro-ondes est étudié par un nombre croissant de chercheurs. Cependant, les raisons de l’effet bénéfique de ce type de frittage ne sont pas clairement identifiées.Dans ce contexte, l’objectif de ce travail a été de vérifier l’influence d’un champ électromagnétique à la fréquence de 2,45 GHz sur la densification de matériaux céramiques. Cet objectif passe donc par une étude comparative du frittage dans une enceinte micro-ondes et dans un four conventionnel. Cependant, la présence du champ électromagnétique dans un four micro-ondes ne permet pas l’utilisation des méthodes conventionnelles pour suivre le frittage. Ainsi, pour comparer les résultats, un dispositif expérimental original contenant un dilatomètre sans contact de haute résolution a été spécifiquement développé. Ce dispositif, permet aussi un suivi de la distribution de température à la surface de la pièce.Pour des cycles thermiques identiques, obtenus en frittage conventionnel et par micro-ondes, l’évolution de la densification de matériaux aux propriétés différentes a été comparée. Ces matériaux sont : l’alumine pure et dopée par 800ppm d’oxyde de magnésium, l’oxyde de zinc et l’hydroxyapatite silicatée. Pour chacun de ces matériaux, le couplage avec les micro-ondes et la répartition du chauffage à la surface de l’échantillon sont aussi discutés. Un effet bénéfique des micro-ondes sur l’évolution de la densification a été mis en évidence pour l’alumine avec ajout de MgO et de manière plus prononcée pour l’oxyde de zinc. / Microwave sintering is known to be a promising sintering technology. Indeed, this method has advantages such as reducing the duration of heat treatment and a significant energy saving compared with conventional processes. Year after year, sintering in a microwave environment is studied by a growing number of researchers. However, the reasons for the beneficial effect of this type of sintering are not clearly identified.In this context, the objective of this work was to verify the influence of an electromagnetic field at a frequency of 2.45 GHz on the densification of ceramic materials. This objective therefore involves a comparative study of sintering in a microwave chamber and in a conventional oven. However, the presence of electromagnetic field in a microwave oven does not allow the use of conventional methods to monitor the sintering. Thus, to compare the results, an experimental system containing a high resolution contactless dilatometer has been specifically developed. This system also allows monitoring of the temperature distribution on the sample surface.For identical thermal cycles, obtained by conventional and microwave sintering, the densification evolution of materials with different properties was compared. These materials are: pure alumina and doped with 800ppm magnesium oxide, zinc oxide and silicon-substituted hydroxyapatite. For each material, the coupling with the microwaves and the temperature distribution on the surface sample are also discussed. A beneficial effect of microwaves on the evolution of densification has been identified for alumina with addition of MgO and more pronounced for zinc oxide.

O presente trabalho trata da manufatura direta de implantes de hidroxiapatita mediante a técnica de prototipagem rápida. A hidroxiapatita proveniente de estrutura óssea mineral bovina possui grande importância dentre os biomateriais devido a sua biocompatibilidade e grande similaridade com a estrutura óssea humana. A prototipagem rápida permite a obtenção de modelos com dimensões e formato miméticos ao do defeito ósseo do paciente e possibilita a obtenção de implantes com porosidade desejada e geometria complexas. Este trabalho tem como objetivo o estudo da obtenção de implantes por três diferentes técnicas de prototipagem rápida: usinagem a verde, 3DPrint e uma inovadora técnica de prototipagem rápida obtida pela polimerização da resina acrílica (fase líquida da barbotina) por luz ultravioleta presente em uma faixa da banda do espectro de luz emitido pelo laser azul (SLB). A diminuta pressão de conformação, típicas das técnicas de prototipagem rápida aditiva, exige pós altamente reativos para efetiva sinterização, dessa forma a hidroxiapatita obtida a partir do fêmur bovino foi calcinada e moída em moinhos de bolas e vibratório na busca de pós submicrométricos. A usinagem a verde de compactados foi considerada como padrão ouro da manufatura e foi aplicada para obtenção de corpos de prova cilíndricos, previamente conformados por prensagem isostática a 100 e 200 MPa e ensaiados por densificação, flexão, dureza e tenacidade à fratura. Introdução de partículas de alumina e whiskers de alumina foram ensaiados na busca de otimização das propriedades mecânicas. Para prototipagem rápida pelo método de SLB, misturas de hidroxiapatita e resina foram submetidas à emissão do laser azul com percurso direcionado em equipamento CNC, onde peças tridimensionais foram prototipadas e sinterizadas. A hidroxiapatita proveniente do osso bovino apresentou características de íons substitucionais de carbonato e após moagens em moinho de bolas seguido de vibratório foi obtida partículas de diâmetro médio equivalente de 0,35 &#181;m que se mostraram reativas para promoção da sinterização. A sinterização a 1300 ºC-2h forneceu as melhores características cristalográfica e de propriedades mecânicas, resultando em corpos referências com hidroxiapatita sem decomposição em outros fosfatos de cálcio com 99,8 % da densidade, resistência mecânica à flexão de 100 MPa, dureza de 483 HV e tenacidade à fratura de 0,6 MPa.m1/2. A introdução de 1 vol% de alumina e whiskers de alumina elevaram a resistência mecânica do corpo para aproximadamente 140 MPa com tenacidade de 0,61 MPa.m1/2. Para a técnica 3DPrint aglomerados esféricos da composição cerâmica deve ter dimensões entre as malhas de 200 e 400 mesh (75 a 38 &#181;m) e o binder deve ter resistividade superior à 290 k&#937;, componentes reativos, emolientes, lubrificantes e estabilizantes. Na manufatura pela técnica SLB a incidência do laser com fluência de 170 mW.s/mm2 promoveu a cura da resina no diâmetro de 0,5 mm e profundidade próxima a 0,5 mm o que, permitiu a prototipagem de scaffolds com camadas de espessura de 0,5 mm resistente ao manuseio para remoção da barbotina não curada. / The study deals with the direct manufacturing of hydroxyapatite implants using rapid prototyping. Hydroxyapatite structure originated from bovine mineral bone has great importance among the biomaterials and biocompatibility due to its great similarity with the human bone structure. Rapid prototyping allows obtaining models with dimensions and shaping mimetics to the patient\'s bone defect and enables the achievement of implants with complex geometry and porosity desired. This study aims to obtain scaffolds for three rapid prototyping techniques: the green machining, 3DPrint and an innovative rapid prototyping technique, obtained by polymerization of acrylic resin (liquid phase of slurry) by ultraviolet light present in a range of the spectrum band a blue light emitted by the laser (SLB). The small conformation pressure, typical of additive rapid prototyping techniques requires highly reactive powders for effective sintering, and then hydroxyapatite obtained from bovine femur was calcined and milled in ball mill and vibratory mill for obtention of sub micrometrics powders. The green machining was considered as the standard of mechanical properties and was used to obtain cylindrical specimens, previously shaped by isostatic pressing at 100 and 200 MPa, and tested by densification, bending, hardness and toughness fracture. Introduction of particles of alumina and alumina whiskers were tested in search engine optimization of the mechanical properties. For rapid prototyping by the method of SLB, mixtures of hydroxyapatite and resin were subjected to blue laser emission directed in CNC equipment where three-dimensional pieces were prototyped and sintered. Hydroxyapatite derived from bovine bone showed characteristics of substitutional carbonate ions and non-stoichiometry, after grinding in a ball mill followed by vibratory mill, particles obtained was equivalent average diameter of 0.35 micrometers that proved reactive to promote sintering. Sintering at 1300 °C-2h gave the best crystallographic characteristics and mechanical properties, resulting in references bodies with hydroxyapatite without decomposition of other calcium phosphates with 99.8 % of density, flexural strength of 100 MPa, hardness of 483 HV and fracture toughness of 0.6 MPa.m1/2. The introduction of 1 vol% alumina and alumina whiskers increased the mechanical strength of the body with approximately 140 MPa and toughness fracture of 0.61 MPa.m1/2. For technical 3DPrint spherical agglomerates of ceramic composition should have dimensions between 200 and 400 mesh (75-38 µm) and the binder should have resistivity higher than 290 k&#937; and components reactive, emollients, lubricants and stabilizers. In the manufacturing technique SLB incidence of the laser with a fluency of 170 mW.s/mm2 promoted curing of the resin of 0.5 mm in diameter and depth about 0.5 mm, which enabled the prototyping of scaffolds with thick layers 0.5 mm resistant to handle for removal of slurry uncured.

Este trabalho visou a produção de suportes para crescimento celular constituídos de compósitos de poli(L-lactídeo) (PLLA) e diversos tipos de fosfatos de cálcio (CaP). A hidroxiapatita deficiente em cálcio (HAD) e o fosfato octacálcico (OCP) em tamanhos submicrométricos foram sintetizados. Hidroxiapatita (HA) e o &#946;-fosfato tricálcico (&#946;-TCP) foram adquiridos da Sigma-Aldrich. Uma mistura de HAD:&#946;-TCP (7:3) também foi preparada. Para melhorar a dispersão da fase mineral em uma matriz polimérica de PLLA, utilizou-se cloreto de lauroíla para funcionalizar a superfície dos CaP. Os espectros de infravermelho e a análise termogravimétrica confirmaram a presença de laurato na superfície de partículas de CaP. As partículas de HA pura também foram funcionalizadas com cloreto de lauroíla para fins comparativos. Compósitos de PLLA/CaP-laurato foram fabricados utilizando a técnica de eletrofiação. A funcionalização da superfície do CaP com laurato resultou em uma melhoria significativa na dispersão de partículas de CaP na matriz polimérica, permitindo a inclusão de até 40% da fase mineral sem comprometer as propriedades mecânicas. Microscopia eletrônica de varredura (SEM) e microscopia eletrônica de transmissão (TEM) foram utilizadas para investigar a morfologia da fibra. A perda de massa e a liberação de cálcio dos suportes durante a degradação em uma solução salina tamponada com fosfato (PBS) foram medidas. HAD e OCP se mostraram ser mais solúveis do que HA e HAD:&#946;-TCP (7:3). A bioatividade dos compósitos foi investigada por imersão das fibras em um fluido corporal simulado (SBF) a 37 °C e pH 7.4. Embora todos os suportes de PLLA/CaP-laurato foram capazes de formar uma camada de apatita em sua superfície após a exposição em SBF, os resultados demonstraram um aumento significativo na mineralização quando HAD, OCP e HAD:&#946;-TCP (7:3) são a fase mineral no compósito em vez da HA. Além disso, malhas produzidas a partir das fibras eletrofiadas de PLLA/CaP-laurato, utilizadas como suporte para crescimento celular, favoreceram a adesão e proliferação de células de fibroblastos de camundongo (NIH-3T3) e células tronco mesenquimais de dentes decíduos humanos (SHED). Finalmente, suportes a partir das malhas PLLA/HAD-laurato e PLLA/OCP-laurato apresentaram melhor desempenho para acelerar a calcificação in vitro como resultado da osteoindução de células SHED e de células pré-osteoblásticas derivadas de calvária de rato (MC3T3-E1) se comparados aqueles contendo HA e HAD:&#946;-TCP (7:3). Esses novos materiais são propostos como biocompósitos de rápida degradação de CaP, para serem utilizados em aplicações de regeneração óssea em ortodontia e ortopedia. / This work aimed at the generation of scaffolds for cellular growth constituted by poly(L-lactide) (PLLA) and several types of calcium phosphate (CaP). Calcium deficient hydroxyapatite (HAD) and octacalcium phosphate (OCP) were synthesized in submicrometer sizes. Hydroxyapatite (HA) and &#946;-tricalcium phosphate (&#946;-TCP) were purchased from Sigma-Aldrich. A mixture of HAD:&#946;-TCP (7:3) also was prepared. In order to improve the dispersion of the mineral phase in a PLLA polymeric matrix, lauroyl chloride was used to functionalize the surface of CaP. Infrared spectra and thermal gravimetric analysis confirmed the presence of laurate on the surface of CaP particles. Neat HA particles were also functionalized with lauryl chloride for comparative purposes. Composites of PLLA/CaP-laurate were fabricated by electrospinning method. The functionalization of CaP surfaces resulted in significant improvement of the dispersion of CaP particles into the polymeric matrix, allowing inclusion of up to 40% of mineral phase without compromising its mechanical properties. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were employed to investigate the morphology of the fibers. The mass loss and calcium release of the scaffolds during degradation in phosphate buffered saline (PBS) were measured. HAD and OCP are more soluble than HA and HAD:&#946;-TCP (7:3). The bioactivity of the composites was investigated by immersing the fibers in a simulated body fluid (SBF) at 37°C and pH 7.4. Although all PLLA/CaP-laurate can form apatite precipitation on their surface after exposition to SBF, the results demonstrate a significant enhancement in the mineralization when HAD, OCP and HAD:&#946;-TCP (7:3) are the mineral phase in the composite instead of HA. Furthermore, mats obtained from PLLA/CaP-laurate electrospun fibers favored the mouse fibroblast cells (NIH-3T3) and stem cells from human exfoliated deciduous teeth (SHED) attachment and proliferation. Finally, PLLA/HAD-laurate and PLLA/OCP-laurate meshes showed better performance in accelerate the calcium phosphate mineralization on its surface as a result of the in vitro osteoinduction of SHEDs and calvaria derived mouse preosteoblastic cells (MC3T3-E1) if compared of those containing HA and HAD:&#946;-TCP (7:3). These new materials are proposed as fast degradation CaP biocomposites to be used in bone regeneration applications in orthodontics and orthopedics.

O presente trabalho trata da manufatura direta de implantes de hidroxiapatita mediante a técnica de prototipagem rápida. A hidroxiapatita proveniente de estrutura óssea mineral bovina possui grande importância dentre os biomateriais devido a sua biocompatibilidade e grande similaridade com a estrutura óssea humana. A prototipagem rápida permite a obtenção de modelos com dimensões e formato miméticos ao do defeito ósseo do paciente e possibilita a obtenção de implantes com porosidade desejada e geometria complexas. Este trabalho tem como objetivo o estudo da obtenção de implantes por três diferentes técnicas de prototipagem rápida: usinagem a verde, 3DPrint e uma inovadora técnica de prototipagem rápida obtida pela polimerização da resina acrílica (fase líquida da barbotina) por luz ultravioleta presente em uma faixa da banda do espectro de luz emitido pelo laser azul (SLB). A diminuta pressão de conformação, típicas das técnicas de prototipagem rápida aditiva, exige pós altamente reativos para efetiva sinterização, dessa forma a hidroxiapatita obtida a partir do fêmur bovino foi calcinada e moída em moinhos de bolas e vibratório na busca de pós submicrométricos. A usinagem a verde de compactados foi considerada como padrão ouro da manufatura e foi aplicada para obtenção de corpos de prova cilíndricos, previamente conformados por prensagem isostática a 100 e 200 MPa e ensaiados por densificação, flexão, dureza e tenacidade à fratura. Introdução de partículas de alumina e whiskers de alumina foram ensaiados na busca de otimização das propriedades mecânicas. Para prototipagem rápida pelo método de SLB, misturas de hidroxiapatita e resina foram submetidas à emissão do laser azul com percurso direcionado em equipamento CNC, onde peças tridimensionais foram prototipadas e sinterizadas. A hidroxiapatita proveniente do osso bovino apresentou características de íons substitucionais de carbonato e após moagens em moinho de bolas seguido de vibratório foi obtida partículas de diâmetro médio equivalente de 0,35 &#181;m que se mostraram reativas para promoção da sinterização. A sinterização a 1300 ºC-2h forneceu as melhores características cristalográfica e de propriedades mecânicas, resultando em corpos referências com hidroxiapatita sem decomposição em outros fosfatos de cálcio com 99,8 % da densidade, resistência mecânica à flexão de 100 MPa, dureza de 483 HV e tenacidade à fratura de 0,6 MPa.m1/2. A introdução de 1 vol% de alumina e whiskers de alumina elevaram a resistência mecânica do corpo para aproximadamente 140 MPa com tenacidade de 0,61 MPa.m1/2. Para a técnica 3DPrint aglomerados esféricos da composição cerâmica deve ter dimensões entre as malhas de 200 e 400 mesh (75 a 38 &#181;m) e o binder deve ter resistividade superior à 290 k&#937;, componentes reativos, emolientes, lubrificantes e estabilizantes. Na manufatura pela técnica SLB a incidência do laser com fluência de 170 mW.s/mm2 promoveu a cura da resina no diâmetro de 0,5 mm e profundidade próxima a 0,5 mm o que, permitiu a prototipagem de scaffolds com camadas de espessura de 0,5 mm resistente ao manuseio para remoção da barbotina não curada. / The study deals with the direct manufacturing of hydroxyapatite implants using rapid prototyping. Hydroxyapatite structure originated from bovine mineral bone has great importance among the biomaterials and biocompatibility due to its great similarity with the human bone structure. Rapid prototyping allows obtaining models with dimensions and shaping mimetics to the patient\'s bone defect and enables the achievement of implants with complex geometry and porosity desired. This study aims to obtain scaffolds for three rapid prototyping techniques: the green machining, 3DPrint and an innovative rapid prototyping technique, obtained by polymerization of acrylic resin (liquid phase of slurry) by ultraviolet light present in a range of the spectrum band a blue light emitted by the laser (SLB). The small conformation pressure, typical of additive rapid prototyping techniques requires highly reactive powders for effective sintering, and then hydroxyapatite obtained from bovine femur was calcined and milled in ball mill and vibratory mill for obtention of sub micrometrics powders. The green machining was considered as the standard of mechanical properties and was used to obtain cylindrical specimens, previously shaped by isostatic pressing at 100 and 200 MPa, and tested by densification, bending, hardness and toughness fracture. Introduction of particles of alumina and alumina whiskers were tested in search engine optimization of the mechanical properties. For rapid prototyping by the method of SLB, mixtures of hydroxyapatite and resin were subjected to blue laser emission directed in CNC equipment where three-dimensional pieces were prototyped and sintered. Hydroxyapatite derived from bovine bone showed characteristics of substitutional carbonate ions and non-stoichiometry, after grinding in a ball mill followed by vibratory mill, particles obtained was equivalent average diameter of 0.35 micrometers that proved reactive to promote sintering. Sintering at 1300 °C-2h gave the best crystallographic characteristics and mechanical properties, resulting in references bodies with hydroxyapatite without decomposition of other calcium phosphates with 99.8 % of density, flexural strength of 100 MPa, hardness of 483 HV and fracture toughness of 0.6 MPa.m1/2. The introduction of 1 vol% alumina and alumina whiskers increased the mechanical strength of the body with approximately 140 MPa and toughness fracture of 0.61 MPa.m1/2. For technical 3DPrint spherical agglomerates of ceramic composition should have dimensions between 200 and 400 mesh (75-38 µm) and the binder should have resistivity higher than 290 k&#937; and components reactive, emollients, lubricants and stabilizers. In the manufacturing technique SLB incidence of the laser with a fluency of 170 mW.s/mm2 promoted curing of the resin of 0.5 mm in diameter and depth about 0.5 mm, which enabled the prototyping of scaffolds with thick layers 0.5 mm resistant to handle for removal of slurry uncured.