Orientador: Horácio Faig Leite / Banca: Paulo Henrique Ferreira Caria / Banca: Jesus Carlos Andreo / Banca: José de Anchieta de Castro e Horta Junior / Banca: Yasmin Rodarte Carvalho / Resumo: Esta pesquisa avaliou o efeito do uso local do alendronato sódico, da hidroxiapatita e da associação alendronato mais hidroxiapatita em diferentes concentrações molares, no processo de reparação de defeitos ósseos em fêmures de ratos. Foi confeccionado no fêmur de 168 ratos (84 machos e 84 fêmeas) um defeito ósseo medindo 2,5mm de diâmetro. Estes animais foram divididos em grupos: controle, amido, alendronato um mol, alendronato dois moles, hidroxiapatita um mol, hidroxiapatita dois moles e alendronato mais hidroxiapatita, de acordo com o material de preenchimento utilizado. Nos animais do grupo controle o defeito ficou preenchido apenas pelo coágulo proveniente do defeito. Os animais foram sacrificados aos sete e 21 dias, quando o fêmur era removido, fixado e descalcificado, para a confecção de lâminas histológicas. Foi realizada análise histológica e histomorfométrica, e os dados obtidos foram submetidos à análise estatística ANOVA. Aos sete dias, observava-se trabéculas ósseas imaturas, contendo grandes osteócitos. Notava-se neoformação óssea em todos os grupos, exceto nos animais machos onde o alendronato se fazia presente. Nos grupos que receberam a hidroxiapatita, visualizava-se as imagens negativas dos grânulos da hidroxiapatita. Aos 21 dias, as trabéculas praticamente fechavam o defeito da maioria dos espécimes estudados. Estatisticamente, houve diferenças entre machos e fêmeas, entre os períodos de observação e com relação ao uso do alendronato. Concluiu-se que a aplicação local do alendronato sódico interferiu negativamente na reparação óssea, que a hidroxiapatita e o alendronato mais a hidroxiapatita não interferiram na reparação e que a reparação óssea foi maior nas fêmeas independentemente do período estudado. / Abstract: This research evaluated the effect of the local use of sodium alendronate, of hydroxyapatite and the association alendronate more hydroxyapatite in different molars concentrations, in the repair of bone defects in femurs of mices. We made in the femur of 168 mices (84 males and 84 females) a bone defect measuring 2,5mm of diameter. We divided these animals in groups: control, starch, alendronate one mol, alendronate two mols, hydroxyapatite one mol, hydroxyapatite two mols and alendronate more hydroxyapatite, in accordance with the material of fulfilment used. In the animals of the control group, the defect was just filled by the clot originating from defect. The animals were sacrificed at seven and 21 days, when the femur was removed, fixed and decalcified, to making histologics laminae. Histological and histomorphometric analyses were performed and the results obtained were submitted to statistical analysis ANOVA. At seven days, it was observed immature bone trabeculae with larges osteocyties. It was noticed bone formation in all groups, exceptin the male animals where the alendronate was present. In the group that received hydroxyapatite, it was visualized negatives images of the hydroxyapatite's granules. At 21 days, the trabeculae practically closed the defect of most studied specimens. Statistically, there were differences between males and females, between the observation periods and with relationship of the alendronate use. It was concluded that the local application of sodium alendronate interfered negatively in bone repair, that the hydroxyapatite and alendronate more hydroxyapatite didn't interfere in the repair and that the bone repair was larger in the females independently of studied period. / Doutor

A busca pelo prolongamento da qualidade da vida tem incentivado o aparecimento de novos materiais. Vidros que possuem fosfato em sua composição têm encontrado um grande espaço em aplicações como biomateriais, e sua utilização como scaffolds pode ser promissora, pois além de sua estrutura ser mais próxima da parte mineral dos tecidos ósseos, eles são materiais com alta solubilidade em meios aquosos. Vidros niobofosfato foram estudados em trabalhos anteriores e provou-se que a adição de óxido de nióbio em vidros fosfato melhora sua durabilidade química. Há também estudos que revelam que o óxido de nióbio pode ser utilizado como biomaterial devido a sua biocompatibilidade. Neste trabalho determinou-se a taxa de dissolução de uma ampla faixa de composições de vidros niobofosfato em soluções aquosas, e em soluções simuladoras de fluído corpóreo (SBF), com diferentes condições de ensaio. Os vidros estudados neste trabalho com composições (32 - 37)P2O5 (2- 15)Nb2O5 (6-7)Na2O (46-53)CaO, % em mol, foram produzidos a partir da mistura e fusão dos precursores em forno elétrico na faixa de temperatura de 1300ºC - 1400ºC por 0,3h. Foram produzidos sete tipos de vidros com composições diferentes, tendo como base a variação do teor de óxido de nióbio. Os vidros foram submetidos a análises de citotoxicidade e foram considerados não citotóxicos. Análises por difração de raios X mostraram que os materiais são amorfos e não se observou a presença de fases cristalinas após imersão tanto em solução aquosa, quanto em SBF. A densidade dos vidros variou de 2,84 a 3,14 g/cm3 em função do teor de óxido de nióbio. Observou-se a perda de massa dos vidros imersos em água e em SBF a 37ºC por 21 dias, sendo que a taxa de dissolução é maior quanto menor o teor de nióbio. As taxas de dissolução também variam de acordo com as condições de imersão das amostras. Micrografias eletrônicas de varredura mostraram a superfície das amostras antes e após imersão. Observou-se a formação de trincas nas superfícies de algumas amostras, resultado da liberação de matéria para o meio lixiviante. Houve aparente formação de uma camada superficial em uma determinada composição. Análises por espectrometria de fluorescência de raios X por energia dispersiva (EDX) determinaram os teores dos elementos presentes nas composições dos vidros, antes e após as imersões. Observou-se a presença de Al2O3, resultado da contaminação do vidro pelo cadinho, e também uma variação significativa no teor de P2O5 causado pela volatilização do mesmo no processo de obtenção do vidro. A variação dos teores dos elementos na superfície de alguns vidros após os períodos de imersão é causada principalmente pela liberação preferencial de P, Na, Al. Os teores dos elementos P, Na, Nb e Ca foram determinados por EDX nas soluções aquosas utilizadas para os testes de lixiviação. / The need to extend and improve the quality of life is leading to the search of new materials. Glasses containing phosphorous in their compositions are considered biomaterials and can be used as scaffolds because they have a structure close to the mineral component of bone tissues, and present relatively high solubility in water. The chemical composition, morphology, and mechanical properties of bioactive glasses can be properly fit to allow bonding with bones. Niobium phosphate glasses have been previously investigated. The addition of niobium oxide improves the chemical durability of phosphate glasses, and they are considered biocompatible. In the present work the dissolution rate of a wide range of niobium phosphate glass compositions were determined in water and Simulated Body Fluid (SBF). The glass compositions were in the range (32 - 37)P2O5 (2-15)Nb2O5 (6-7)Na2O (46-53)CaO mol%, and they were prepared by melting reagent grade chemical compounds in the temperature range 1300ºC - 1400ºC for 0.3h in an electrical furnace. Seven different glasses were prepared. The glasses were considered non-toxic after performing cytotoxicity tests. No evidence of crystalline phases was observed on X-rays diffraction patterns before and after the corrosion tests. The glass densities are in the range of 2.84 - 3.14 g/cm3. The density increases as the amount of niobium oxide increases. A mass loss was determined after immersing glass samples in water and in SBF at 37ºC during 21 days. The dissolution rate decreases as the amount of niobium oxide increases. The dissolution rate depends on the immersion medium and conditions. Cracks on the glass surfaces were observed by scanning electron microscopy after the corrosion tests which are related to the material release from the glass surface to the liquid. There is also evidence of formation of a layer on the surface of a specific glass composition. The glass compositions were determined before and after the corrosion tests by X-ray Fluorescence Spectrometry (EDS). Aluminum was detected in the glass composition. This element is related to the contamination of the glass by the crucible used in the glass melting. A significant variation of the amount of P2O5 compared to the nominal composition was also noticed, due to the volatilization of phosphorous during the glass melting. The surface glass composition changes during the leaching tests in water or SBF because of the preferential release of P, Na, and Al. EDS was also used to determine the concentration of P, Na, Nb, and Ca in the leaching solution by using the dry drop method.

A instalação de implantes odontológicos requer a presença de substrato ósseo adequado para garantir estabilidade e equilíbrio biomecânico. A deficiência óssea requer procedimentos de enxertia para adequar o volume para a instalação de implantes, porém a utilização de enxertos autógenos causa aumento de morbidade ao paciente e o uso de material homógeno e xenógeno apresenta dúvidas quanto à reação autoimune, transmissão de doenças e ao grau de reabsorção do enxerto. Com o grande desenvolvimento científico e tecnológico dos biomateriais, os materiais cerâmicos, tornaram-se alternativas promissoras para a recomposição da estrutura óssea perdida. As cerâmicas à base de fosfato de cálcio como a hidroxiapatita (HA) e o beta- fosfato tricálcido (beta-TCP), são materiais que apresentam qualidades desejáveis no processo de neoformação óssea como, por exemplo, a biocompatibilidade, bioatividade e osteocondutividade. A proposta deste trabalho é desenvolver e estudar corpos de prova na forma de cúpula oca de hidroxiapatita preenchidos por coágulo, beta- TCP e composto vitamínico, para estudar a osteogênese supracortical, a partir do potencial osteocondutor da cúpula de HA. As cúpulas foram obtidas por prensagem isostática a 200 MPa e sinterização ao ar a 1100°C por 60 minutos. As caracterizações físico-químicas das matérias-primas e da cúpula de HA foram realizadas por difração de raios X, microscopia eletrônica de varredura e determinação da densidade. Na caracterização biológica, foram realizados o teste de citotoxicidade in vitro e ensaio in vivo. Foram designados 9 coelhos (raça Nova Zelândia), sendo instaladas 18 cúpulas, divididas em três grupos, de acordo com o preenchimento: controle, composto vitamínico e β-TCP em forma de pó. O período de reparação tecidual foi de 8 semanas, no qual foram aplicados marcadores de fluorescência. Após o período de cicatrização e eutanásia, as amostras foram incluídas em resina para a obtenção das lâminas e observadas em microscópio de fluorescência, para avaliar a quantidade de tecido ósseo neoformado, em microscópio de campo claro, para verificar as células presentes no tecido formado e por Espectroscopia de Energia Dispersiva, para análise química, da formação no interior das cúpulas. Como resultados, a cúpula de hidroxiapatita apresenta bom desempenho como arcabouço para neoformação óssea acima da cortical da tíbia de coelhos, pois manteve-se íntegra, com boa estabilidade e boa integração ao tecido ósseo, e principalmente pela neoformação óssea, demonstrando seu potencial osteocondutor. Em relação aos materiais de preenchimento, o beta-TCP apresenta maior valor de área de osso neoformado, em comparação com o coágulo. Nas cúpulas com preenchimento de composto vitamínico, não há formação de tecido ósseo pela não reabsorção do material. / The installation of dental implants requires the presence of adequate bone substrate to ensure stability and biomechanical balance. Deficiency requires bone grafting procedures to adjust the volume for implant placement, but the use of autogenous grafts cause increased morbidity to the patient and the use of homogenous and xenogenous materials has doubts about the autoimmune reaction, transmission of disease and the degree of resorption of the graft. With the great scientific and technological development of biomaterials, ceramic materials, have become promising alternatives for restoration of lost bone structure. The ceramics based on calcium phosphate such as hydroxyapatite (HA) and beta-tricalcium phosphate (beta-TCP) are materials having desirable qualities in the process of bone formation, for example, biocompatibility, bioactivity and osteoconductivity. The purpose of this work is to develop and study the dome-shaped hydroxyapatite filled with blood clot, beta-TCP and vitamin compound, to study osteogenesis supracortical from the osteoconductive potential of the dome of HA. The domes were obtained by isostatic pressing at 200 MPa and sintered in air at 1100 ° C for 60 minutes. The physico-chemical characterization of raw materials and the dome of HA were performed by X-ray diffraction, scanning electron microscopy and density determination. In biological characterization were performed tests for in vitro cytotoxicity and tests in vivo. Were designated 9 rabbits (New Zeland), and installed 18 domes, divided into three groups, according to the filling: control, vitamin compound and β-TCP in powder form. The period of wound healing was 8 weeks, when a fluorescence marker was applied. After the healing period and euthanasia, the samples were embedded in resin to obtain the slides and observed under fluorescence microscope to evaluate the amount of newly formed bone tissue in bright field microscope to check the cells present in the tissue and by Energy Dispersive Spectroscopy for chemical analysis, inside the domes. As a result, the hydroxyapatite dome has good performance as scaffold for bone formation above the cortical tibia of rabbits, it remained intact, with good stability and good integration with bone tissue, especially bone formation, demonstrating osteoconductive potential. Regarding the filling materials, beta-TCP has a higher value of area of new bone formation compared to the clot. In the domes-filled vitamin compound, there is no formation of bone resorption by not material.

A reconstrução de defeitos ósseos é um problema que afeta milhões de pessoas, que a medicina tenta resolver. Uma alternativa para a solução deste problema tem sido o desenvolvimento de biomateriais que atuem no processo de reparação óssea. O colágeno é um polímero de origem natural capaz de promover cicatrização e regeneração óssea e juntamente com a hidroxiapatita são os principais componentes encontrados no tecido ósseo. Vários trabalhos têm sido reportados com matrizes mineralizadas de colágeno tipo I em diferentes formas como em géis, membranas e esponjas, mas a mineralização in vitro de matrizes acelulares obtidas de tecidos biológicos sem a perda da estrutura colagênica não tem sido descrito. Este trabalho teve como objetivo a mineralização in vitro e a caracterização de matrizes de colágeno aniônico obtidas de pele porcina, pericárdio bovino e serosa porcina. Os tecidos foram tratados em temperatura ambiente com solução alcalina por períodos variáveis de 0 à 96h e mineralizados pelo processo de imersão alternada. Os materiais obtidos foram caracterizados pela avaliação preliminar da citotoxicidade in vitro, termogravimetria (TG/DTG), calorimetria exploratória diferencial (DSC), microscopia eletrônica de varredura (MEV), dispersão de raios X (EDS), difração de raios X (DRX) e absorção no infravermelho (FT-IR). Não foi observada citotoxicidade em nenhuma das matrizes avaliadas, contudo foi necessário um pré-tratamento nas matrizes de pele porcina para remoção de gordura. Os resultados de DSC mostraram a integridade da matriz colagênica após o tratamento alcalino. O aumento no tempo desse tratamento diminui a temperatura de desnaturação sendo observado um efeito maior nas matrizes de pele porcina seguidas por pericárdio bovino e serosa porcina. A mineralização induz a um aumento na temperatura de desnaturação em todos os casos. As curvas TG apresentaram perdas de massa relacionadas à água presente no material, decomposição da proteína e carbonização do material orgânico e um resíduo após 750 °C que foi associado ao material inorgânico presente na forma de hidroxiapatita, sendo as matrizes de serosa porcina as de maior teor de mineralização. As matrizes mineralizadas tendem a um aumento na estabilidade térmica do colágeno quando comparadas com as matrizes hidrolisadas. Os espectros FT-IR mostraram a presença de íons fosfatos e a interação de íons cálcio com o colágeno. As relações Ca/P obtidas por EDS foram aquelas esperadas em comparação com o valor teórico para hidroxiapatita (HA) e resultados de DRX confirmaram a obtenção de HA amorfa como principal produto de mineralização. Pelas fotomicrografias obtidas por MEV pôde-se observar que as fibras de colágeno tornam-se mais desestruturadas quando há um aumento no tempo de hidrolise e que a deposição de sais ocorreu de forma heterogênea, disposta em aglomerados esféricos no formato de agulhas por toda a superfície e interior, exceto para matrizes derivadas de pele porcina que não são mineralizadas internamente devido a sua espessura. Os resultados obtidos demonstraram que é possível a mineralização in vitro de matrizes de colágeno tipo I obtidas de diferentes tecidos biológicos em diferentes tempos de hidrólise, produzindo um material com potencial de uso para regeneração óssea. / The reconstruction of osseous defects is still a problem that affects millions of people and medicine tries to solve it. One alternative to solve these problems has been the development of biomaterials that can be used as inductors in the osseous repair process. Collagen is a natural polymer able to promote healing and bone regeneration, and among hydroxyapatite (HA) is the main component found in bone tissue. Several mineralized collagen scaffolds are described in literature, in the form of gel, membranes and films, however, in vitro mineralization of acellular matrices, obtained from biological tissues without the loss of collagenic structure, has not been reported. The objective of this work was the mineralization and characterization of anionic collagen matrices obtained from porcine skin, bovine pericardium and porcine serosa. Biological tissues were treated at room temperature for 0-96h in alkaline solution and mineralized by alternate soaking method. Materials were characterized by preliminary assay of in vitro cytotoxicity, differential scanning calorimetry (DSC), termogravimetric analysis (TG/DTG), scanning electronic microscopy (SEM), energy dispersive x-ray analysis (EDS), x-ray diffraction (XRD), and Fourier Transform Infrared Spectroscopy (FTIR). No cytotoxicity was observed in any of the evaluated matrices; however, a pre-treatment of porcine skin matrices, for fat removal, was necessary. DSC results showed the integrity of collagen matrices after alkaline treatment. Denaturation temperature is dependent of time of alkaline treatment, and this effect is greater for porcine skin matrix, followed by bovine pericardium and porcine serosa. TG/DTG curves showed weight losses associated with release of water, degradation of protein structure and combustion of residual organic components. Residues were obtained at 750°C and associated to hydroxyapatite, being porcine serosa matrix the most mineralized. All mineralized matrices showed an increase in collagen thermal stability when compared to hydrolyzed matrices. FTIR spectra showed the presence of phosphate ions and the interaction of calcium ions with collagen. Ca/P ratios obtained by EDS were as expected when compared with literature values for HA, and RDX results confirmed amorphous HA as the main mineralization product. MEV analysis showed that collagen fibers were more affected for longer hydrolysis times, and that salt deposition was heterogeneous, with crystals grouped in spherical agglomerates in a needle-like shape throughout surface and inner, except for porcine skin derived matrices that were not internally mineralized due their width. Obtained results demonstrated that in vitro mineralization of type I collagen matrices, using different sources of biological tissues and hydrolysis time was possible, producing a material with potential to be used in bone regeneration.

Copper ions are widely reported to have pro-angiogenic properties and can be incorporated into bone substitute bioceramics as bio-instructive cues to stimulate infiltration of blood vessels into the material after implantation. By this, the viability of bone forming cells within the scaffold (which decreases rapidly with increasing depth from the surface) could be enhanced, and the healing process (resorption and replacement of the scaffold with new, natural bone) hastened. Pure-phase copper-doped hydroxyapatite (CuHA) materials with x = 0 - 1 in the nominal formula Ca10(PO4)6CuxOy(H)z were prepared by solid state synthesis at 1100 °C. Attempted preparation of compositions with y = 0.1 and 0.5 in the nominal formula Ca10−yCuy(PO4)6(OH)2 by an aqueous precipitation method led to formation of biphasic products containing considerable amounts of β-tricalcium phosphate. Dissolution tests in TRIS buffer, cell culture medium and citric acid buffer indicated that copper ions are released from CuHA materials at concentrations that increase with copper content in the materials and soaking time, and are in a physiologically-relevant range. This offers the potential to tune copper ion release by controlling the copper content of CuHA materials. In vitro in cultures of human osteoblast-like cells and human mesenchymal stem cells (hMSCs), copper ions released from CuHA downregulated ALP expression in both cell types and (particularly for hMSCs) upregulated VEGF expression. In vivo, the prepared copper-containing materials had pro-angiogenic and possible inflammatory effects in the chick embryo yolk sac membrane and chorioallantoic membrane angiogenesis assays. Copper ions released from beads grafted into the developing chick limb affected the integrity of developing blood vessels in the graft vicinity, causing haemorrhaging. The results suggest that the coupling of angiogenesis and osteogenesis, perhaps through the hypoxia and NO pathways, are important for copper's biological effects, and with further investigation and careful control of dose and timing these effects may be better understood and controlled.

Les réactions de catalyse asymétrique en phase homogène ont connu un développement fulgurant au cours des dernières décennies et de nombreux complexes ou ligands ont été décrits dans la littérature. La séparation et le recyclage efficace du catalyseur (ou des ligands) onéreux apparaît ainsi comme l'un des challenges qui conjugue à la fois les attentes de la synthèse organique industrielle et de la chimie verte. Parmi les différentes solutions envisagées, l'immobilisation du catalyseur sur un support solide (poudre) à l'aide d'une " chaîne moléculaire " apparaît comme une réponse séduisante : le catalyseur (couple métal-ligand) est récupéré par une simple filtration et peut être réutilisé. Notre projet est axé sur des catalyseurs chiraux développés par notre équipe et appliqués dans des réactions de Suzuki-Miyaura et d'hydrogénation asymétrique. L'utilisation d'hydroxyapatite (HAP) comme support inorganique de catalyseurs organométalliques est un domaine pratiquement inexploré qui s'inscrit pourtant dans une logique de développement durable en répondant à des préoccupations environnementales et économiques : matériaux biocompatibles, synthèse en milieux aqueux (absence de solvant organique). Nous nous sommes intéressés notamment au greffage de la surface d'HAP avec des alkoxysilanes fonctionnalisés (R-Si(OR')3). La nature des interactions a été étudiée par différentes techniques (spectroscopies FTIR, RAMAN, RMN, DRX, MEB, MET, etc.). Ces supports ont donné des résultats modérés dans la réaction de Suzuki-Miyaura. L'utilisation de silice mésoporeuse comme support a aussi été étudiée. Nous avons synthétisé une variante fonctionnalisée d'un ligand de type P, S ferrocénique ayant démontré de bonne activités et énantiosélectivités en catalyse homogène. Nous l'avons greffé sur différents supports (HAP, silices,...) et réalisé les premiers essais en catalyse d'hydrogénation asymétrique et comparé l'influence du support sur l'activité. / The asymmetric catalysis in homogeneous phase experienced a rapid development over the past decades and many complexes or ligands have been described in the literature. The separation and effective recycling of the catalyst (or ligands) appears expensive and as one of the challenges that combines both expectations of industrial organic synthesis and green chemistry. Among the various solutions proposed, immobilization of the catalyst on a solid support (powder) using a "molecular chain" appears as a seductive answer: the catalyst (metal-ligand pair) is recovered by simple filtration and can be reused. Our project is centered on chiral catalysts developed by our team and applied under Suzuki-Miyaura reactions and asymmetric hydrogenation. The use of hydroxyapatite (HAP) as organometallic catalysts inorganic support is a virtually unexplored field which nevertheless anchored in a process of sustainable development by responding to environmental and economic concerns: biocompatible synthetic materials in aqueous media (no organic solvent). We focused in particular grafting the HAP surface with functionalized alkoxysilanes (R-Si(OR')3). The nature of the interaction has been studied by various techniques (FTIR spectroscopy, Raman, NMR, XRD, SEM, TEM, etc.). These supports have shown moderate results in the Suzuki-Miyaura reaction. The use of mesoporous silica as a support has also been studied. We synthesized a variant of a functionalized ligand P,S ferrocenic have demonstrated good activities and enantioselectivities in homogeneous catalysis. Grafted on different media (HAP, silica, ...), we have made the first tests in catalysis of asymmetric hydrogenation and compared the influence of the media on activity.

No description available.

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Nanocrystalline hydroxyapatite (HAp) powder of size 10-20 nm was synthesized applying microwave radiation using calcium nitrate tetrahydrate and sodium phosphate dibasic anhydrous as the starting materials. Microwave power of 600 W and Ca/P ratio of 1.66 in the starting chemicals served as the major factors in the synthesis of nanocrystalline HAp powder. Phase composition and evolution were studied using X-ray diffraction (XRD) technique. Morphology, agglomeration and particle-size of the synthesized powder were studied using Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM) techniques. Energy Dispersive Spectrum (EDS) was used to determine the elemental composition of the powder. Thermal properties were investigated using Thermogravimetric (TG) and Differential Thermal Analysis (DTA) and, Fourier Transform Infrared Spectroscopy (FTIR). As-synthesized HAP and TiO2 powder was uniaxially compacted into cylindrical pellets at a pressure of 78.69 MPa and sintered at high temperature to examine the effects of sintering on nano powder particles, densification behavior, phase evolution and mechanical properties. Phase evolution was studied using XRD whereas microstructure evolution was studied by SEM. To determine the mechanical properties Vickers hardness and biaxial flexural strength tests were performed. Biodegradability and biomechanical strength of nano-HAp and TiO2 samples sintered at high temperature was assessed in Simulated Body Fluid (SBF) having ionic concentration as that of human plasma. Biodegradation and change in mechanical properties of the sintered samples when kept in SBF and maintained in a dynamic condition were studied in terms of weight loss, change in Vickers hardness and biaxial flexural strength as a function of time. Highly crystalline HAp powder was achieved after microwave synthesis with average particle size in the range of 10-20 nm which was further confirmed by HR-TEM and SEM. Calcination of the synthesized powder at 500[degrees]C for 2 h increased the average particle size to 21 nm. EDS confirmed the elemental composition of the powder. FTIR analysis showed the presence of phosphate band which confirmed the presence of HAp at high temperature. TG analysis showed 23% weight-loss upon heating up to 1200[degrees]C, contributed by the removal of adsorbed and possible lattice water, decarboxylation of HAp or condensation of HPO42- releasing water. HAp along with [Beta]NaCaPO4 and Na3Ca6(PO4)5 was observed at 950[degrees]C, 1100[degrees]C and 1200[degrees]C. Density of HAp samples continued increasing with the increase in temperature from 1100[degrees]C to 1250[degrees]C and sintered density of 2.88 g/cc was obtained at 1250[degrees]C. Hardness and Biaxial strength of the HAp samples increased with temperature and maximum hardness value of 249.53 [plus or minus] 3.98 HV and biaxial flexural strength of 52.07 [plus or minus] 4.96 MPa were observed for samples sintered at 1250[degrees]C. Biaxial strength and hardness of TiO2 samples increased with temperature. Maximum biaxial flexural strength of 125.5 [plus or minus] 11.07 MPa and maximum hardness of 643.27 [plus or minus] 7.96 HV were observed for the TiO2 sample sintered at 1500[degrees]C which was much more than that of sintered HAp samples. Decrease in mass, hardness and biaxial strength of HAp samples sintered at 1250[degrees]C and TiO2 samples sintered at 1400[degrees]C showed biodegradation in SBF, maintained in a dynamic state, as a function of time. Increase in mass was observed for the HAp samples in SBF during the fourth week.

L'industrie laitière représente le deuxième secteur alimentaire par le volume de sa production au Québec. Son développement s'explique par la croissance des besoins en matières grasses laitières, notamment en produits transformés tels que le fromage. En production fromagère, la concentration du lait par ultrafiltration (UF) entraîne le rejet d'importants volumes de perméat de lait contenant du lactose et des sels; lui conférant un fort impact environnemental. Pour produire 1 kilogramme de fromage, 9 litres de lactosérum sont rejetés. Il contient des protéines, du lactose et des sels. Les protéines sont valorisées sous forme de concentrés par UF; ce qui génère de larges volumes de perméat de lactosérum. Les résidus organiques de la transformation laitière sont de 264 972 tonnes/an au Québec. Le lactose des perméats est valorisé par cristallisation ou bio fermentation, mais la présence de minéraux est limitante. L'induction d'une précipitation phosphocalcique sélective avant la valorisation du lactose permettrait l'extraction de ces éléments sous forme d'hydroxyapatites (HAp), utilisées comme supplément dans les formulations alimentaires et la récupération conjointe de lactose. Pour favoriser la précipitation des HAp, une concentration du perméat par osmose inverse(OI) a été réalisée. D'autres paramètres ont aussi été étudiés : pH, température et ensemencement. Les précipités ont été récupérés par centrifugation, lyophilisés puis chauffés à 550°C pour éliminer la phase organique. Pour suivre l'efficacité de la précipitation, la composition des principaux éléments salins (K, Ca, Na, P, Mg) a été déterminée par spectrométrie de masse à plasma à couplage inductif et le Ca ionique de la phase soluble a été mesuré avec une électrode. Les phases cristallines obtenues ont été analysées par diffraction des rayons X et par FTIR. La morphologie des particules a été étudiée par microscopie électronique à balayage. Les résultats ont confirmé que le taux de phosphate de calcium précipité a augmenté avec l'ensemencement, la chaleur et l'alcalinisation; surtout dans les perméats concentrés par OI. L'alcalinisation induit le changement de phase vers la forme HAp, démontrant le potentiel de la précipitation sélective du phosphate de calcium et de l'impact positif de l'OI sur son efficacité. Cette étude ouvre la voie à la valorisation des minéraux à partir des perméats de fromagerie, qui a été très peu investiguée comparativement à celle du lactose. / The dairy industry represents the second-largest food sector in Quebec. Its development could be explained by the growth of the dairy fat needs with the demand for processed products, such as butter or cheese, increasing yearly. The concentration of milk proteins by ultrafiltration (UF) leads to the rejection of important volumes of milk permeate (WP), which contains lactose and minerals, responsible for its environmental impact. The production of one kg of cheese rejected 9 liters of whey, representing 1.2 billion tons per year. Whey is rich in proteins, lactose, and mineral components. Whey proteins are generally concentrated by UF and used in various foods for their excellent technological and nutritional properties. This process generates large volumes of whey permeate. The dairy industry is responsible for rejecting a weight of 264 972 tons/years of organic matter in the province of Quebec. Lactose can be valorized by crystallization of bio-fermentation, but salts content could be a limit factor. The induction of selective phosphocalcic precipitation of those elements into hydroxyapatite (HAp) could permit the supplementation of Ca in food formulas and recover lactose simultaneously. To favor HAp precipitation, permeate concentration by reverse osmosis (RO) was tried. Other parameters were studied, including the pH, heating treatments, and DCP seeding. Precipitates were condensed by centrifugation, lyophilized, and then put in a 550°C furnace to remove organic traces. Specific milk salts recovered in the precipitate (K, Ca, Na, P, Mg) was determined by ICP to follow the efficiency of the process. Ionic Ca from the aqueous phase was measured as well with an electrode. Crystalline phases were analyzed by X-ray diffraction and FTIR. The particle's morphology was studied by scanning electron microscopy. Results confirmed that the calcium-phosphate precipitated rate increased with solution's seeding, heating, and alkalinization. Reverse osmosis increased the precipitation. Alkalinization inducts the phase change from simple apatic minerals to complex ones such as HAp. These results demonstrate the potential of selective calcium-phosphate precipitation and RO's positive impact on reaction efficiency. This study opens the path to cheese permeate salt's valorization, low investigated until now.