Dissertations / Theses on the topic 'Calcium phosphate bioceramic'
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Ramírez, Caballero Silvia. "Composites made of bioceramic and chitosan physical hydrogel as potential bone substitutes." Thesis, Lyon, 2018. http://www.theses.fr/2018LYSEI010/document.
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Les substituts osseux synthétiques servent au remplacement temporaire des tissus osseux, favorisent la formation, la croissance et la survie de l’os et sont biorésorbables. Aucun matériau monophasé ne remplissant complètement ces exigences, un matériau composite bioinspiré est une alternative possible. L’objectif de cette thèse était par conséquent d’étudier la synthèse et les propriétés de deux composites biocéramiques/biopolymères : des hydrogels physiques de chitosane minéralisés avec de l’apatite, et une hardystonite architecturée imprégnée par des hydrogels physiques de chitosane. Afin d’obtenir le premier matériau, deux approches ont été développées. La première a consisté à fabriquer des hydrogels physiques de chitosane puis à les minéraliser avec de l’apatite ; la formation de microcapillaires se produit avec des conditions de synthèse spécifiques, et les précipités d’apatite ont été trouvés uniquement à la surface des hydrogels. La seconde approche consiste à convertir des suspensions homogènes contenant le phosphate de calcium et le chitosane en hydrogels de chitosane minéralisés par l’apatite. Les suspensions ont été préparées soit avec un mélange simultané, soit avec des mélanges successifs de suspensions phosphates de calcium avec les solutions de chitosane. Des agrégats minéraux plus petits avec une distribution plus uniforme ont été formés avec la méthode des mélanges successifs. Cela est attribué à une meilleure homogénéité, une viscosité plus faible et l’absence de chitosane. De manière générale, trois paramètres influencent les propriétés mécaniques d’hydrogels de chitosane minéralisés : la base utilisée pour la gélification (déterminant la vitesse de gélification : une grande vitesse conserve l’enchevêtrement des chaînes, résultant en une meilleure élasticité) ; la densité de la réticulation physique (cela induit un module de conservation plus important) et la force ionique (qui mène au désenchevêtrement des chaînes de chitosane, donc, à un faible module de conservation). Cette compréhension a permis l’utilisation de ces suspensions de phosphate de calcium-chitosane en tant qu’encre pour l’impression 3D. Les hydrogels de chitosane et les hydrogels minéralisés ne sont pas cytotoxiques. Pour fabriquer le second matériau, une encre pré-céramique a été imprimée en 3D puis frittée pour former une céramique d’hardystonite cristalline. Les scaffolds d’hardystonite ont été imprégnés par la solution de chitosane, converties ensuite en hydrogels physiques de chitosane. A plus forte concentration de chitosane, la viscosité de la solution était plus grande et l’imprégnation de la matrice plus lente. Avec une vitesse de gélification plus importante, qui dépend de la base utilisée pour la gélification, la perte de poids est plus faible pendant la gélification. L’hydrogel de chitosane a partiellement rempli les pores participant au support de charges externes et à la dissipation d’énergie par ruptureBone substitutes, an approach to attend social demand for bone healing and reparation, are temporary replacements of bone tissue, promote bone formation and growth and finally are bioresorbed. No single material meets these requirements; an alternative is a bioinspired composite material. The objective of this thesis was thus to study the synthesis and properties of two bioceramics/biopolymer composites: chitosan physical hydrogels mineralized with apatite and hardystonite scaffolds impregnated with chitosan physical hydrogels. To obtain the first material, two strategies were developed. The first one consisted in the fabrication of chitosan physical hydrogels and its subsequent mineralization with apatite; the formation of micro-capillaries occurred under particular synthesis conditions, and apatite precipitates were found only on the surface of hydrogels. The second strategy consisted in a simultaneous conversion of chitosan-calcium phosphate suspensions into chitosan-apatite hydrogels. The suspensions were prepared by sequential or simultaneous mixing of calcium and phosphate suspensions with chitosan solutions. Smaller and more uniformly distributed mineral aggregates were formed following sequential mixing, attributed to higher homogeneity, lower viscosity and no-presence of chitosan. This enabled the use of these chitosan-calcium phosphate suspensions as inks for 3-D printing. In general, three factors impacted the mechanical properties of mineralized chitosan hydrogels: the base used for gelation (determining the gelation rate: a higher rate preserved chain entanglement, resulting in higher elasticity); the density of physical crosslinks (hence a higher storage modulus) and the ionic strength (that led to chitosan chain disentanglements, thus, low storage modulus). Chitosan hydrogels and mineralized hydrogels were not cytotoxic, having no deleterious effects on osteoblasts proliferation. To fabricate the second material, pre-ceramic ink was 3-D printed and then sintered to form crystalline hardystonite ceramic. Hardystonite scaffolds were impregnated with chitosan solution that was, next, converted to chitosan physical hydrogel. At higher chitosan concentration, viscosity of solution was higher and scaffold impregnation was lower. At higher gelation rate, which depend on base used for gelation, lower weight loss during gelation. Chitosan hydrogel partially filled the pores contributing to bearing of external loads and to energy dissipated by fracture
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Seifert, Gabrielle Victoria. "Amorphous Calcium Phosphate Composites of a Phenylalanine-based Poly(ester urea) Poly(1-PHE-6)." University of Akron / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=akron1460388339.
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Dórea, Neto Francisco de Assis. "Avaliação do cimento de alfa-fosfato tricálcico em artrodeses tarsocrurais experimentais em cães /." Jaboticabal : [s.n.], 2007. http://hdl.handle.net/11449/101130.
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Orientador: João Guilherme Padilha FilhoBanca: Paola Castro Morais
Banca: Patricia Popak Giordano
Banca: Delphim da Graça Macoris
Banca: Márcia Rita Fernandes Machado
Resumo: Objetivou-se nesta pesquisa estudar o comportamento e a bioatividade do cimento de alfa-fosfato tricalcico de dupla pega em artrodeses tarsocrurais. Utilizaram-se seis caes, adultos, macho ou femeas, sem raca definida, com idades entre dois e cinco anos e pesando entre 18 e 30 kg. Foram constituidos dois grupos com 3 animais cada: um grupo onde empregou-se o cimento de ¿-fosfato tricalcico de dupla pega (Grupo I) e outro utilizando osso esponjoso autogeno (Grupo II). A avaliacao radiografica ocorreu aos 30, 45, 60, 90 e 120 dias apos o procedimento cirurgico. Radiograficamente, a fusao dos ossos das articulacoes ocorreu em ambos os grupos apos o 30o dia, sem qualquer reacao adversa ou do tipo corpo estranho. A estabilidade das articulacoes foi satisfatoria com a utilizacao de fixadores esqueleticos externos. Histologicamente, aos 120 dias, observaram-se diferencas na maturidade das celulas osseas entre os dois grupos ocorrendo absorcao lenta e remodelacao da bioceramica (Grupo I). Relativamente a microscopia eletronica de varredura, foi observada formacao de osso novo diretamente na superficie da bioceramica, sem causar formacao de lacuna entre a interface osso-ceramica. O cimento de alfa-fosfato tricalcico de dupla pega demonstrou ter uma boa resistencia mecanica, propriedades de biocompatibilidade, crescimento osseo direto sobre a ceramica, osteoconducao e, ainda, ocorrencia de lenta absorcao quando comparado ao enxerto ósseo.
Abstract: The purpose of this research was to estuding the behaviour and bioactivity of the á-tricalcium phosphate cement double setting in tarsocrural arthrodesis. Therefore, six canines, both male and female adults mongrel dogs, aged between two and five years old and weighing between 12 and 18kg, were the objects of this study. They were vi divided into two groups with three animals each. On Group I á-tricalcium phosphate cement double setting was used. The Group II, also considered the control group, autogenous cancellous bone graft was used. The periods chosen for the radiographic analysis were 30, 45, 60, 90 and 120 days after surgery. Radiographyc bone fusions on the joints were observed on both groups after 30 days. The stabilization of the joints with external fixators proved to be very satisfactory. No reaction of foreigh body or infection process due to the material used was observed. The histological analysis performed after 120 days after surgery revealed differences in terms of the maturity of the bone cells between the two groups, showing slow absorption and remodelling of the bioceramic (Group I). In terms of the scanning electronic microscopy, bone growth was detected, right on the surface of the bioceramic, without causing gap formation on the bone-ceramic joint. The á-tricalcium phosphate cement double setting demonstrated to have a good mechanical resistance, bioacompatibility properties, direct bone growth on the ceramic and osteocondution and, still, the occurrence of slow absorption when compared to the bone graft.
Doutor
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Dórea, Neto Francisco de Assis [UNESP]. "Avaliação do cimento de alfa-fosfato tricálcico em artrodeses tarsocrurais experimentais em cães." Universidade Estadual Paulista (UNESP), 2007. http://hdl.handle.net/11449/101130.
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Objetivou-se nesta pesquisa estudar o comportamento e a bioatividade do cimento de alfa-fosfato tricalcico de dupla pega em artrodeses tarsocrurais. Utilizaram-se seis caes, adultos, macho ou femeas, sem raca definida, com idades entre dois e cinco anos e pesando entre 18 e 30 kg. Foram constituidos dois grupos com 3 animais cada: um grupo onde empregou-se o cimento de ¿-fosfato tricalcico de dupla pega (Grupo I) e outro utilizando osso esponjoso autogeno (Grupo II). A avaliacao radiografica ocorreu aos 30, 45, 60, 90 e 120 dias apos o procedimento cirurgico. Radiograficamente, a fusao dos ossos das articulacoes ocorreu em ambos os grupos apos o 30o dia, sem qualquer reacao adversa ou do tipo corpo estranho. A estabilidade das articulacoes foi satisfatoria com a utilizacao de fixadores esqueleticos externos. Histologicamente, aos 120 dias, observaram-se diferencas na maturidade das celulas osseas entre os dois grupos ocorrendo absorcao lenta e remodelacao da bioceramica (Grupo I). Relativamente a microscopia eletronica de varredura, foi observada formacao de osso novo diretamente na superficie da bioceramica, sem causar formacao de lacuna entre a interface osso-ceramica. O cimento de alfa-fosfato tricalcico de dupla pega demonstrou ter uma boa resistencia mecanica, propriedades de biocompatibilidade, crescimento osseo direto sobre a ceramica, osteoconducao e, ainda, ocorrencia de lenta absorcao quando comparado ao enxerto ósseo.
The purpose of this research was to estuding the behaviour and bioactivity of the á-tricalcium phosphate cement double setting in tarsocrural arthrodesis. Therefore, six canines, both male and female adults mongrel dogs, aged between two and five years old and weighing between 12 and 18kg, were the objects of this study. They were vi divided into two groups with three animals each. On Group I á-tricalcium phosphate cement double setting was used. The Group II, also considered the control group, autogenous cancellous bone graft was used. The periods chosen for the radiographic analysis were 30, 45, 60, 90 and 120 days after surgery. Radiographyc bone fusions on the joints were observed on both groups after 30 days. The stabilization of the joints with external fixators proved to be very satisfactory. No reaction of foreigh body or infection process due to the material used was observed. The histological analysis performed after 120 days after surgery revealed differences in terms of the maturity of the bone cells between the two groups, showing slow absorption and remodelling of the bioceramic (Group I). In terms of the scanning electronic microscopy, bone growth was detected, right on the surface of the bioceramic, without causing gap formation on the bone-ceramic joint. The á-tricalcium phosphate cement double setting demonstrated to have a good mechanical resistance, bioacompatibility properties, direct bone growth on the ceramic and osteocondution and, still, the occurrence of slow absorption when compared to the bone graft.
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Hsu, Yu-Hsiu. "Fabrication of porous calcium phosphate bioceramics." Thesis, University of Bath, 2005. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.425267.
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Fernandes, Juliana Machado. "Síntese e caracterização de cimento de alfa-fosfato tricálcico reforçado com hidrogel de alginato de sódio e PVA para aplicação médico-odontológica." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2013. http://hdl.handle.net/10183/96502.
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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.
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Santos, Rodrigo Brandão Medeiros dos. "Síntese e caracterização de pós nanoestruturados de fosfato de cálcio e nanocompósitos hidroxiapatita/sílica-gel." Universidade do Estado de Santa Catarina, 2009. http://tede.udesc.br/handle/handle/1750.
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The loss of an organ or a part of the body generates, besides the loss of function, social and psychological disorders. The materials used to replace bone fall into a class called biomaterials and should have physical and biological properties compatible with living tissue hosts. The objective of this study is to optimize the method of synthesis and characterization of a bone matrix of calcium phosphate nanostructured and nanocomposite calcium phosphate /SiO2n at concentrations of 1%, 2%, 3% and 5% by volume. Were carried out morphological characterization of nanoparticles, nanostructured mineral powders and biomaterials obtained by sintering at 1200 C/2h. Finally, studies were performed on the mechanical behavior of nanostructured biomaterials. The process of synthesis of nanostructured powders proved to be efficient and optimized, allowing to obtain the matrix of calcium phosphate and nanocomposites with silica gel. Silica gel influence the surface energy of the matrix of calcium phosphate and this phenomenon has influenced the particle size of the nanocomposites, phase transformation and sinterability of the matrix of calcium phosphate. Tests of mechanical properties showed that the increase in percentual silica gel in the phosphate matrix tends to reduce the mechanical strength (hardness, strength and fracture toughness). Only the nanocomposite with 1% silica showed improvement in mechanical properties after annealing.
A perda de um órgão ou de uma parte do corpo humano gera, além da perda da função, transtornos sociais e psicológicos. Os materiais utilizados na substituição de ossos enquadram-se em uma classe denominada de biomateriais e devem apresentar propriedades físicas e biológicas compatíveis com os tecidos vivos hospedeiros. Esse trabalho tem como objetivo otimizar o método de síntese e caracterização de uma matriz óssea de fosfato de cálcio nanoestruturada e de nanocompósitos fosfato de cálcio/SiO2n, nas concentrações de 1%, 2%, 3% e 5% em volume. Foram realizadas caracterizações morfológicas das nanopartículas, mineralógica dos pós nanoestruturados e dos biomateriais obtidos da sinterização a 1200ºC/2h. Por fim, foram realizados estudos sobre o comportamento mecânico dos biomateriais nanoestruturados. O processo de síntese de pós nanoestruturados mostrou-se eficiente e otimizado, permitindo a obtenção da matriz de fosfato de cálcio e dos nanocompósitos com sílica gel. A sílica gel influenciou na energia de superfície da matriz de fosfato de cálcio e esse fenômeno influenciou no tamanho de partícula dos nanocompósitos, transformação de fase e sinterabilidade da matriz de fosfato de cálcio. Os ensaios de propriedades mecânicas mostraram que o aumento do percentual de sílica gel na matriz de fosfato tende a reduzir a resistência mecânica (microdureza, flexão e tenacidade à fratura). Apenas o nanocompósito com 1% de sílica apresentou melhora nas propriedades mecânicas após o recozimento.
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Gittings, Jonathan Paul. "Fabrication and properties of novel open porous calcium phosphate bioceramics." Thesis, University of Bath, 2005. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.421251.
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Novotná, Lenka. "Bioceramic Materials for Advanced Medical Applications." Doctoral thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2015. http://www.nusl.cz/ntk/nusl-234578.
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Cílem disertační práce bylo připravit trojrozměrné biokeramické podpůrné systémy („skafoldy“), které by v budoucnu mohly pomoci při rekonstrukci a regeneraci poškozených kostních tkání. Porézní keramické pěny byly připraveny dvěma způsoby – replikační technikou a polymerizací in situ. Co se složení týče, byly studovány keramické materiály zejména na bázi oxidu hlinitého, zirkoničitého a kalcium fosfátů. Byl studován jednak vliv procesních parametrů jako je složení suspenzí a jejich viskozit, dále pak vliv tepelného zpracování na strukturu a výsledné vlastnosti připravených materiálů. U slinutých pěn byla pomocí rastrovací elektronové mikroskopie hodnocena zejména morfologie – velikost pórů, jejich propojenost a celková porozita, charakterizace mikrostruktury nebyla opomenuta. Dále bylo stanoveno fázové složení a pevnost v tlaku. Z biologických vlastností byla testována a diskutována bioaktivita a cytotoxicita materiálů. Disertační práce je členěna do několika částí. V literární rešerši je popsána stavba a vlastnosti kosti, požadavky kladené na kostní náhrady, výhody a nevýhody současně používaných materiálů a způsoby přípravy keramických pěn. Následuje experimentální část, kde byly nejprve studovány pěny připravené replikační technikou. Všechny takto vyrobené pěny měly propojené póry o velikostech 300 až 2000 m, celková porozita se pohybovala v rozmezí 50 – 99 %. Pevnost pěn na bázi kalcium fosfátů – 0,3 MPa (při celkové porozitě 80%) byla nedostatečná pro kostní náhrady, kde je požadována pevnost větší než 2 MPa. Kalcium fosfátové keramiky byly tedy zpevněny buďto inertním jádrem na bázi oxidu hlinitého nebo ATZ (oxidem zirkoničitým zhouževnatělým oxidem hlinitým). Dále byl přípraven částicový kompozit, ve kterým byl hydroxyapatit pojený oxidem křemičitým. Pevnost pěn se podařilo zvýšit až na více než 20 MPa. V poslední kapitole experimentální části byly studovány keramické pěny pěněné in situ, kde byly póry vytvářeny oxidem uhličitým unikajícím během reakce mezi diisokyanátem a polyalkoholem. Po vypálení polymerního pojiva měly pěny propojené póry o průměrné velikosti 80 až 550 m. Celková porozita se pohybovala v rozmezí 76 – 99%. Výhodou oproti replikační technice byly plné trámečky bez velké středové dutiny vznikající vypálením polymerní předlohy. Žádný ze studovaných materiálů nebyl pro buňky toxický, navíc všechny studované pěny vykazovaly bioaktivní chování. Z hlediska kostního tkáňového inženýrství se jako nejslibnější jeví kompozitní materiál zpevněný oxidem křemičitým.
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Bernard, Sheldon Ainsworth. "Influence of silicon dioxide, magnesium oxide and zinc oxide on resorbable tricalcium phosphate based bioceramics." Online access for everyone, 2005. http://www.dissertations.wsu.edu/Thesis/Fall2005/s%5Fbernard%5F083005.pdf.
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Kim, Hyunbin. "Synthesis and control of microstructure, mechanical properties, and bioactivity in biphasic and preferentially oriented calcium phosphate bioceramics." Birmingham, Ala. : University of Alabama at Birmingham, 2007. http://www.mhsl.uab.edu/dt/2007p/kim.pdf.
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Sun, Zehra Pinar. "Structural And Mechanical Investigations Of Magnesium And Fluoride Doped Nano Calcium Phosphates." Master's thesis, METU, 2009. http://etd.lib.metu.edu.tr/upload/2/12610764/index.pdf.
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The aim of this study was to investigate the microstructure and mechanical properties of pure and Mg2+ and F- doped nano-calcium phosphate (CaP) powders, which were synthesized by precipitation method. After the drying and calcination processes, the samples were sintered at 1100ºC for 1 hour. High densities were achieved except for the 7.5 % mole Mg doped samples. Microstructure of the CaPs were investigated by X- ray diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR) and Scanning Electron Microscopy (SEM). Due to the Mg substitution, &
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-TCP phase was detected besides HAp, resulting in the formation of HAp/ &
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-TCP biphasic composites with different compositions. The substitutions of the ions have been verified by the decrease in the hexagonal unit cell volumes of the doped CaPs. FTIR spectra revealed the characteristic absorption bands of HAp, &
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-TCP and the ones that were resulted from the F-OH bonds and substitution of the Mg2+ ions. The SEM results revealed the grain sizes in the range of ~197 nm-740 nm. In general, the micro hardness and diametral tensile strength tests revealed that Mg2+ ions in large amounts (7.5 % mole) had negative effects on the mechanical properties of the samples, while substitution of the F- ions had a positive effect on their mechanical properties.
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Pejchalová, Lucie. "Přizpůsobení fázového složení a mikrostruktury vápenatých fosforečnanů aplikovaných v regenerativní medicíně." Master's thesis, Vysoké učení technické v Brně. Fakulta chemická, 2020. http://www.nusl.cz/ntk/nusl-414116.
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Vápenaté fosforečnany jsou nejčastěji využívané keramické materiály v medicíně pro regeneraci kostní tkáně. Vápenaté fosforečnany jsou biokompatibilní, bioaktivní a mezi sebou se odlišují především rozpustností a související degradací v organismu, proto jsou nejčastěji využívány k regeneraci malých defektů nebo jako vrstvy na kovových implantátech. U již zmíněné rozpustnosti materiálu po implantaci, hraje důležitou roli poměr zastoupení jednotlivých vápenatých fosforečnanů, od kterého se pak odvíjí rychlost degradace materiálu v organismu. Tato práce se zabývá vlivem tvarovacích metod na mikrostrukturu a zejména fázové složení vápenatých fosforečnanů. Výchozím materiálem pro pozorování změn ve fázovém složení byl komerční hydroxyapatit, který byl upraven kalcinací při 800 °C po dobu jedné hodiny. Při kalcinaci došlo k vytvoření dvoufázové směsi, obsahující hydroxyapatit a -fosforečnan vápenatý. Tato dvoufázová směs byla poté využita pro přípravu suspenze s plněním 15 obj.%, a také k přímé přípravě polotovarů s různou výslednou mikrostrukturou a fázovým složením. S cílem zjistit vliv procesu byly v této práci porovnány vzorky připravené pomocí metod: freeze-casting, izostatické lisování za studena, uniaxiální lisování a suspenzní odlévání. U polotovarů a slinutých vzorků byla provedena charakterizace mikrostruktury a analýza fázového složení. V práci se potvrdil vliv tvarovací metody na oba stanovené parametry – mikrostrukturu a fázové složení. Nově pak bylo zjištěno, že se zvyšující se hodnotou porozity a velikostí pórů se zvyšuje i zastoupení hydroxyapatitu ve vzorcích. Tento trend byl pozorován u vzorků vykazujících unimodální i bimodální zastoupení velikosti pórů.
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Gariboldi, Maria Isabella. "Effect of calcium phosphate ceramic architectural features on the self-assembly of microvessels in vitro." Thesis, University of Cambridge, 2018. https://www.repository.cam.ac.uk/handle/1810/283005.
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One of the greatest obstacles to clinical translation of bone tissue engineering is the inability to effectively and efficiently vascularise scaffolds. This limits the size of defects that can be repaired, as blood perfusion is necessary to provide nutrient and waste exchange to tissue at the core of scaffolds. The goal of this work was to systematically explore whether architecture, at a scale of hundreds of microns, can be used to direct the growth of microvessels into the core of scaffolds. A pipeline was developed for the production of hydroxyapatite surfaces with controlled architecture. Three batches of hydroxyapatite were used with two different particle morphologies and size distributions. On sintering, one batch remained phase pure and the other two batches were biphasic mixtures of α-tricalcium phosphate (α-TCP) and hydroxyapatite. Sample production methods based on slip casting of a hydroxyapatite-gelatin slurry were explored. The most successful of these involved the use of curable silicone to produce moulds of high-resolution, three dimensional (3D) printed parts with the desired design. Parts were dried and sintered to produce patterned surfaces with higher resolution than obtainable through conventional 3D printing techniques. Given the difficulties associated with the structural reproducibility of concave pores architectures in 3D reported in the literature, in this work, a 2.5D model has been developed that varies architectural parameters in a controlled manner. Six contrasting architectures consisting of semi-circular ridges and grooves were produced. Grooves and ridges were designed to have widths of 330 μm and 660 μm, with periodicities, respectively, of 1240 μm and 630 μm. Groove depth was varied between 150 μm and 585 μm. Co-cultures of endothelial cells and osteoblasts were optimised and used to grow microcapillary-like structures (referred to as "microvessels") on substrates. Literature shows that these precursors to microcapillaries contain lumina and can produce functional vasculature, demonstrating their clinical promise. The effects of the composition and surface texture of grooved samples on microvessel formation were studied. It was found that surface microtopography and phase purity (α-TCP content) did not affect microvessel formation. However, hydroxyapatite architecture was found to significantly affect microvessel location and orientation. Microvessels were found to form predominantly in grooves or between convexities. Two metrics - the degree of alignment (DOA) and the degree of containment (DOC) - were developed to measure the alignment of endothelial cell structures and their localisation in grooves. For all patterned samples, the CD31 (an endothelial cell marker) signal was at least 2.5 times higher along grooves versus perpendicular to grooves. In addition, the average signal was at least two times higher within grooves than outside grooves for all samples. Small deep grooves had the highest DOA and DOC (6.13 and 4.05 respectively), and individual, highly aligned microvessels were formed. An image analysis method that compares sample X-ray microtomography sections to original designs to quantify architectural distortion was developed. This method will serve as a useful tool for improvements to architectural control for future studies. This body of work shows the crucial influence of architecture on microvessel self-assembly at the hundreds of micron scale. It also highlights that microvessel formation has a relatively low sensitivity to phase composition and microtopography. These findings have important implications for the design of porous scaffolds and the refinement of fabrication technologies. While important results were shown for six preliminary architectures, this work represents a toolkit that can be applied to screen any 2.5D architecture for its angiogenic potential. This work has laid the foundations that will allow elucidating the precise correspondence between architecture and microvessel organisation, ultimately enabling the "engineering" of microvasculature by tuning local scaffold design to achieve desirable microvessel properties.
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Sartori, Thauane Aparecida Inácio da Costa. "Biocerâmicas porosas de alumina e de alumina-zircônia recobertas com fosfatos de cálcio para implantes ósseos." Universidade de São Paulo, 2015. http://www.teses.usp.br/teses/disponiveis/74/74133/tde-17092015-092938/.
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A utilização de biocerâmicas de natureza inerte, como a alumia e zircônia, têm ao longo dos últimos anos, estimulado grande interesse científico no entendimento dos mecanismos biológicos dos biomateriais. Por sua vez, cerâmicas bioativas (a base de fosfatos de cálcio) apresentam uma melhor estabilidade química superficial e biocompatibilidade, entretanto, suas limitações estão relacionadas a baixos valores de propriedades mecânicas. Assim, a técnica de recobrimento de alumina-zircônia, em soluções de concentrações semelhantes ao fluido corpóreo, possibilita o desenvolvimento de uma camada bioativa, que induz uma melhor interação osso-implante. Além disso, cerâmicas porosas (arcabouços) com morfologia e distribuição bem definida são reconhecidamente empregadas como suporte para o crescimento, fixação e desenvolvimento de tecido no interior do implante. Neste sentido, o objetivo deste trabalho foi obter corpos de prova porosos de alumina e alumina contendo 5% em volume de inclusões nanométricas de zircônia. A obtenção dos corpos porosos se baseou no processo gelcasting de espumas, sem atmosfera controlada, seguido pelo tratamento químico de superfície com ácido fosfórico e finalmente, pelo recobrimento biomimético para o período de 7, 14 e 21 dias de incubação. As caracterizações dos corpos de prova foram realizadas através de porosidade aparente, microscopia eletrônica de varredura (MEV) aliada à espectroscopia por dispersão de energia (EDS) e ensaio de compressão diametral. Os resultados indicaram a obtenção de corpos porosos de alumina e alumina-zircônia com alta homogeneidade de poros em toda a estrutura com elevada interconectividade. O método de recobrimento biomimético promoveu uma formação efetiva de apatita na superfície e no interior dos poros dos corpos porosos em todas as composições e condições estudadas, contudo, essa formação se apresentou mais uniformemente distribuída na superfície dos nanocompósitos porosos de alumina-zircônia tratados com ácido fosfórico, indicando que a presença da zircônia nanométrica estimula a formação da nucleação da apatita a partir das interações entre os grupos (Zr-OH). Além disso, bons valores de resistência mecânica à compressão da matriz foram alcançados, potencializando a aplicação dos corpos porosos de alumina e de alumina-zircônia recobertos com fosfato de cálcio como bons substitutos ósseos.The use of naturally inert bioceramics as alumina and zirconia has over the last few years spurred great scientific interest in understanding the biological mechanisms of biomaterials. In turn, ceramic biactive (by calcium phosphate), have a better surface biocompatibility and chemical stability. However, their limitations are related to low values of mechanical properties. Thus, the alumina-zirconia coating technique, in similar concentrations to the body fluid solutions, enables the development of a bioactive layer, which induces a better implantbone interaction. Furthermore, porous ceramic (scaffolds) with a defined morphology and distribution are known by using it as support for the growth, attachment and tissue development within the implant. In this sense, the objective of this study was to obtain porous bodies of alumina and alumina containing 5%vol. nanometric zirconia inclusions. The obtaining of porous bodies based on the gelcasting foams process without controlled atmosphere, followed by chemical surface treatment with phosphoric acid, and finally the biomimetic coating to the period of 7, 14 and 21 days of incubation. The characterizations of the samples were performed by apparent porosity, scanning electron microscopy (SEM) coupled with energy dispersive spectroscopy (EDS) and diametrical compression test. The results indicated porous bodies of alumina and alumina-zirconia with high homogeneity throughout the pore structure with high interconnectivity. The biomimetic coating method promoted effective formation of apatite on the surface and within the pores of the porous bodies in all investigated compositions and conditions, however, such a formation is presented more evenly distributed on the surface of porous alumina-zirconia nanocomposite acid-treated phosphoric, indicating that the presence of nano-zirconia stimulates the formation of nucleation of apatite from interactions between groups (Zr-OH). Furthermore, good values of compressive strength of the matrix that have been achieved, enhancing the application of the porous bodies of alumina and alumina-zirconia coated with calcium phosphate bone substitutes as well.
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Charbonnier, Baptiste. "Développement de procédés de mise en forme et de caractérisation pour l’élaboration de biocéramiques en apatites phosphocalciques carbonatées." Thesis, Lyon, 2016. http://www.theses.fr/2016LYSEM031/document.
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Les changements sociétaux tels que la personnalisation de la médecine, ainsi que la volonté de mieux comprendre la biologie de l’os modifie notre approche de fabrication des biomatériaux. Ces derniers se doivent ainsi d’être sur-mesure, c’est-à-dire capables de répondre à une problématique particulière. Ceci implique plus précisément dans le cas qui nous intéresse, à savoir l’os, la maîtrise de leur architecture et de leur comportement en milieu biologique (e.g., biodégradabilité).Malgré leurs atouts incontestables pour ce domaine, les biocéramiques en hydroxyapatite (HA) restent cantonnées à des usages modestes (e.g., comblement de petits défauts) ; en cause, des propriétés de biodégradation, d’ostéoconduction ou encore d’ostéoinduction souvent inadaptées aux problématiques contemporaines. Pour pallier ces limitations, nous avons entrepris deux voies de modulation des propriétés biologiques de l’HA, une voie « chimique », basée sur l’incorporation d’ions carbonate dans la structure apatitique, et une voie « procédé », reposant sur le potentiel de la fabrication additive.Des poudres d’hydroxyapatites phosphocalciques carbonatées (CHA) ont été préparées. Les ions carbonate pouvant occuper les sites hydroxyle et phosphate de l’HA, une méthode de quantification sélective du taux de substitution sur chacun de ces sites a été mise au point. Cette méthode spectroscopique novatrice ouvre de nombreuses opportunités d’études appliquées et fondamentales des CHA, abordées dans ce manuscrit, et constitue également un outil qui pourrait se révéler précieux dans l’optique de mise sur le marché de dispositifs médicaux en CHA (e.g., norme ISO).Basé sur une technologie de fabrication additive, un procédé de fabrication de biocéramiques d’architecture complexe, reproductible, flexible, fiable, de haute précision ( 5 µm) et peu coûteux, a été développé et optimisé. Cet outil de fabrication a été mis en œuvre pour répondre à des questions biologiques à finalité fondamentale et thérapeutiqueThe current approach to produce biomaterials tends to evolve due to societal change such as the development of personalized medicine or the eagerness to better understand bone biology. Hence, biomaterials, which specifications depends of their intended applications, have to be custom made. For bone tissue engineering, this implies to control the scaffold architecture and behaviour in a biological environment (e.g., biodegradability).Despite their indisputable qualities, the use of hydroxyapatite (HA) bioceramics tend to be limited to basic applications (e.g. filling small defects) because of biodegradation, osteoconduction, or osteoinduction properties that do not match the actual needs. To exceed these limitations, we explored two modifications paths to tune HA biologic properties: a “chemical” approach based on incorporation of carbonate ions into apatitic structure, and a “process” approach, built around additive manufacturing singular potential.Carbonated phosphocalcic hydroxyapatites (CHA) powders were prepared. As carbonate ions may occupy HA hydroxyl and phosphate sites, a selective method to quantify their ratio in each site by IR spectroscopy has been developed. This innovative spectroscopic method opens numerous opportunities for applied and fundamental studies of CHA, but could also be considered as a precious standard for a future release of CHA medical devices (e.g. ISO norm).A cheap, flexible, robust and reliable manufacturing process based on an additive manufacturing technology has been developed and optimized, leading to the production of bioceramics with complex architectural features (accuracy 5 µm).This manufacturing process has been implemented in biological studies with fundamental and therapeutic purposes
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Despang, Florian. "Hydroxylapatit-Verbundwerkstoffe und -Biokeramiken mit parallel orientierten Porenkanälen für das Tissue Engineering von Knochen." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2013. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-116658.
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Für das Tissue Engineering von Knochen werden poröse dreidimensionale Substrate (Scaffolds) als Zellträger benötigt, die in der vorliegenden Arbeit über keramische Technologie hergestellt wurden. Neben dem strukturierten und getrockneten Verbundwerkstoff (Grünkörper) und der Sinterkeramik wurde auch der Zwischenzustand nach Ausheizen der organischen Phase (Braunkörper) evaluiert. Bei der Herstellung blieb die Architektur der parallel orientierten Kanalporen, die über den Sol-Gel-Prozess der gerichteten ionotropen Gelbildung des Alginates erzeugt wurde, in allen Materialzuständen erhalten.
Die Herstellungstechnologie wurde derart optimiert, dass die neuartigen anisotropen Scaffolds allen prinzipiell gestellten Forderungen für das Tissue Engineering entsprachen – sie waren porös mit weithin einstellbarer Porengröße, sterilisierbar, gut handhabbar unter Zellkulturbedingungen, biokompatibel und degradabel. Der unerwartete Favorit der Biomaterialentwicklung, der Braunkörper – eine nanokristalline, poröse Hydroxylapatit-Biokeramik – lag in einer ersten in vivo-Studie nach 4 Wochen integriert im Knochen vor. Die beobachtete Knochenneubildung deutete auf eine osteokonduktive Wirkung des Materials hin.
Die in der vorliegenden Arbeit untersuchten Technologien und Biomaterialien bieten eine Basis für weitere Forschung und motivieren zur Weiterentwicklung und Nutzung als Scaffold für das Tissue Engineering oder Knochenersatzmaterial unter Verwendung der interessanten Architektur.
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Vojníková, Michaela. "Biokeramický skafold pro vedení nervů připravený metodou freeze-casting." Master's thesis, Vysoké učení technické v Brně. Fakulta chemická, 2021. http://www.nusl.cz/ntk/nusl-444536.
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Pre regeneráciu a rast poranených nervových vlákien bolo preskúmaných mnoho postupov, no výsledný rast axónov je často náhodný až dezorganizovaný a odráža sa na zložitejšom zotavovaní pacienta. V tejto práci boli vyrobené nové skafoldy s mikroštruktúrnymi a mechanickými vlastnosťami nervového skafoldu pomocou metódy freeze-casting. Konkrétne boli vyrobené biokeramické skafoldy na báze fosforečnanov vápenatých, oxidu titaničitého alebo oxidu zirkoničitého. Pomocou kontrolovaného rastu ľadu v jednom smere bola pripravená orientovaná mikroštruktúra. Pozorovanie pomocou skenovacej elektrónovej mikroskopie potvrdilo lineárne orientované póry (lamelárny systém), v ktorých priemerná veľkosť pórov klesala so zvyšujúcou sa rýchlosťou mrazenia. Skafoldy pripravené pomocou mrazenia v tekutom dusíku vykazovali vynikajúce mechanické vlastnosti, kde pevnosť v ohybe bola získaná v rozmedzí 10–17 MPa. Tie isté skafoldy mali vzdialenosť medzilamelamelárnych priestorov 10–30 µm, ktorých parametre sú vhodné pre nervové skafoldy. Biokompatibilita bola vyhodnotená pomocou Schwannových buniek in vitro, kde bola pozorovaná adhézia a rast v lamelárnom smere. Cytotoxické testy odhalili negatívny vplyv vyššej koncentrácie vápnika na prežitie Schwannových buniek. Pripravené skafoldy mali schopnosť tvorby apatitu na povrchu v podobe embryonálnych a nukleačných centier a apatitu samotného. Skafoldy na báze fosforečnanov vápenatých a oxidu titaničitého vykazovali sľubné regeneračné vlastnosti, konkrétne adhéziu a rast prostredníctvom pórovitej štruktúry a taktiež vynikajúce mechanické vlastnosti.
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El, Felss Nadia. "Céramiques phosphocalciques fonctionnalisées : étude des propriétés de surface par méthodes spectroscopiques." Thesis, Limoges, 2018. http://www.theses.fr/2018LIMO0109/document.
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Ce travail s’inscrit dans le cadre général du développement de biomatériaux ostéoinducteurs pour la réparation de grands défauts osseux. L’étude est une contribution à la compréhension des interactions physiques et chimiques entre des céramiques phosphocalciques et deux protéines d’intérêt : la fibronectine, protéine d’adhésion cellulaire, et le VEGF (pour Vascular Endothelial Growth factor) qui est impliqué dans la vascularisation et l’amélioration de la formation osseuse.Les interactions physiques fibronectine/biocéramique ont été étudiées par spectroscopie de force afin d’évaluer l’influence de la topographie et de la composition chimique de céramiques phosphocalciques en hydroxyapatite (HA), hydroxyapatite silicatée (SiHA) et hydroxyapatite carbonatée (CHA) sur l’adhésion de la fibronectine. Les résultats obtenus par cartographie de forces mettent en évidence une absence d’incidence de la chimie des céramiques polies sur la répartition en surface et l’intensité des forces d’adhésion. En revanche ces dernières sont plus fortes au niveau des joints de grains des céramiques non polies mettant en avant une influence de la topographie de surface des matériaux modulée par la chimie.Le protocole de fonctionnalisation par le VEGF consiste en trois étapes : silanisation, addition du SM(PEG)6 et immobilisation du VEGF. Les interactions chimiques VEGF/biocéramique ont été étudiées principalement par imagerie Raman pour suivre ces étapes successives de la fonctionnalisation par le VEGF de céramiques polies en hydroxyapatite (HA) et hydroxyapatite carbonatée (CHA). Cette approche a permis de cartographier l’évolution chimique de la surface des matériaux et de mettre en évidence la distribution spatiale ainsi que les réactions préférentielles entre les molécules intermédiaires et le VEGF en fonction de la nature du substratThis work is ascribed within the framework of the development of osteoinductive biomaterials for the repair large bone defects. It is a contribution to the understanding of the physical and chemical interactions between phosphocalcic ceramics and two proteins of interest: fibronectin (Fn), a cell adhesion protein, and Vascular Endothelial Growth Factor (VEGF) which is involved in vascularisation and improvement of bone formation.Fibronectin/bioceramic physical interactions were studied by force spectroscopy to evaluate the influence of the topography and the chemical composition of phosphocalcic ceramics made of hydroxyapatite (HA), silicated hydroxyapatite (SiHA) and carbonated hydroxyapatite (CHA) on fibronectin adhesion. The results obtained in terms of force cartography do not indicate any impact of the polished ceramics chemistry on the surface distribution and intensity of adhesion forces. However, these forces are more intense at the level of the grain boundaries of unpolished ceramics, highlighting an influence of the topography modulated by the chemical composition.The protocol for functionalisation by VEGF consists of three steps: silanisation, addition of SM(PEG)6 and immobilisation of VEGF. VEGF/bioceramic chemical interactions were studied mainly by Raman imaging in order to follow the successive steps of the functionalisation by VEGF of the polished surface of ceramics made of hydroxyapatite (HA) and carbonated hydroxyapatite (CHA). This approach allowed to map the surface chemical changes and to point out the spatial distribution as well as the preferential reactions between the intermediate molecules and VEGF depending of the substrate
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FOOK, Ana Carolina Brasil Marcelino, and Ana Carolina Brasil MARCELINO. "Desenvolvimento de biocerâmicas porosas para regeneração óssea." Universidade Federal de Campina Grande, 2008. http://dspace.sti.ufcg.edu.br:8080/jspui/handle/riufcg/2017.
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Atualmente na área de biomateriais destinados à regeneração óssea, existe um interesse no desenvolvimento de materiais capazes de estimular a resposta biológica necessária para restabelecer as funções do tecido ósseo em caso de perda, falta ou mau funcionamento. A hidroxiapatita (HA, Caio(P04)6(OH)2) que apresenta semelhança com a fase mineral dos ossos e dos dentes, é biocompatível e osteocondutiva, e tem excelente afinidade química e biológica com os tecidos ósseos. Este trabalho teve como objetivo desenvolver biocerâmicas porosas para regeneração óssea utilizando a técnica réplica da esponja polimérica. Foram utilizadas esponjas de poliuretano com densidades variadas para a obtenção dos suportes porosos. Os resultados de espectroscopia no infravermelho e difração de raios X revelaram a formação da HA monofásica e confirmaram a eficiência da reação de neutralização utilizada na obtenção da pasta cerâmica. As análises por microscopia eletrônica de varredura revelaram suportes com poros interconectados com tamanhos variados na ordem de macro (>100um) e microporosidade (1-20um) em menor ou maior grau dependendo da densidade da esponja utilizada na produção das amostras. Estes resultados foram comprovados pela análise de porosimetria de mercúrio. Os suportes porosos HAPU-28 destacaram-se por apresentar maior porosidade total em comparação com os suportes produzidos com esponja de menor densidade (HAPU-20 e HAPU-25). Os resultados apontam os suportes porosos de HA desenvolvidos nesse estudo como materiais em potencial para aplicação como substitutos ósseos por apresentarem alta porosidade (>70%), composição química, interconectividade e tamanhos dos poros adequados à regeneração óssea.
Currently in the area of biomateriais destined for bone regeneration, exists an interest in the development of materiais capable to stimulate the biological reply necessary to reestablish the functions of the bone tissue in loss, lack or bad functioning case. The hydroxyapatite (HA, Caio(P04)6(OH)2) that shows similarity with the mineral phase of bone and teeth, it is biocompatible and osteoconductive, and has excellent chemical and biological affinity with the bone tissue. This study aimed to develop porous bioceramics for bone regeneration using the replica of the polymeric sponge technique. Polyurethane sponges were used with varying densities to obtain the scaffolds. Results of infrared spectroscopy and X-ray diffraction analysis revealed the formation of the HA monophasic and confirmed the efficiency of the neutralization reaction used in obtaining the slurry ceramics. Analyses by scanning electron microscopy revealed scaffolds with interconnected pores with different sizes on the order of macro and microporosity to a lesser or greater degree depending on the density of foam used in the production of samples. These results were proven by the analysis of the mercury porosimetry. The porous scaffold HAPU28 detached by showing higher total porosity compared to scaffold produced with sponge of lower density (HAPU-20 and HAPU-25). The results indicate the porous HA scaffolds developed in this study as potential materiais for application as bone substitutes to have high porosity (> 70%), chemical composition, interconnectivity and pore sizes appropriate to the bone regeneration.
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Liao, Jia-hui, and 廖家輝. "Preparation of Hydroxyapatite and Calcium Phosphate Bioceramic Materials from the Aqueous Solution at Room Temperature." Thesis, 2005. http://ndltd.ncl.edu.tw/handle/44539673272701119866.
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碩士義守大學
材料科學與工程學系碩士班
93
A chemical reaction method was used to study the formation mechanisms of hydroxyapatite or calcium phosphate salts on the surface of different ceramic substrates, through controlling different concentrations of Ca2+、PO43- and OH- in the aqueous solution. In this study, sintered Ca3-(PO4)2, Al2O3 and ZrO2 ceramic composites were fabricated to be plate-like substrates for this particular chemical coating process. In the chemical coating or reacting process, different ceramic substrates were dipped in the 1 M H3PO4 aqueous solution at T=25~80℃ and pH=0.7~11, to observe phase existence and microstructure of surface coating. Surface coating was formed to be CaHPO4?2H2O (DCPD) after the Ca3(PO4)2 substrate was dipped in the 1 M H3PO4 aqueous solution at pH=2.5 under a sufficient Ca2+ source from Ca(OH)2 . The surface coating of DCPD was further treated in the alkaline solution, 2.5 M NaOH and it was further transformed into hydroxyapatite. From experimental results, HA was formed easily at a higher pH value. As the pH value increased, the surface morphology of these coatings were changed into the network structure from the initial plate structure. In the Al2O3/Ca3(PO4)2 and ZrO2/Ca3(PO4)2 composite substrates, HA was much easier to form in the alkaline solution when the volume ratio of Ca3(PO4)3/Al2O3 or Ca3- (PO4)2/ ZrO2 was 7/3.
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Pujari-Palmer, Michael. "The biological and physical performance of high strength dicalcium phosphate cement in physiologically relevant models." Doctoral thesis, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-319495.
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The chemical properties of calcium phosphate cements (CPCs) are very similar to the mineral phase of bone. CPCs are, consequently, very effective substrates (scaffolds) for tissue engineering; bone and stem cells attach readily, and can proliferate and differentiate to form new bone tissue. Unlike other CPCs that may remain largely unchanged in the body for years, such as hydroxyapatite, dicalcium phosphates are remodelled by the body and rapidly converted to new bone. Unfortunately, the dicalcium phosphates are also typically too weak to support load bearing in the human body. Our laboratory has recently developed a novel, high strength brushite CPC, (hsCPC), which can reach 10-50 fold higher failure strength than many commercially available CPCs. The aim of this thesis was to investigate the physical, chemical and biological performance of hsCPCs in physiologically relevant model of drug release, load bearing, osteoconductivity, and as a scaffold for bone tissue engineering. Multiple CPCs were compared in a model of screw augmentation to determine whether the physical properties of the cement, such as bulk strength and porosity, affected orthopedic screw holding strength. In an in vitro model of bone regeneration stem cells were grown on macroporous scaffolds that were fabricated from hsCPC. Drug releasing scaffolds were fabricated to examine whether the low porosity of hsCPC impeded drug release during a 4 week incubation period. The biological activity of an incorporated drug, Rebamipide, was examined after acute and chronic incubation periods. In the drug release study it was noted that the biological response to hsCPC was significantly better than tissue culture grade polystyrene, even in groups without drug. The mechanism underlying this biological response was further investigated by testing the effect of pyrophosphate, a common cement additive, on bone cell proliferation and differentiation. This thesis concludes that a high strength cement can produce significant improvement in screw augmentation strength, if there is sufficient cortical bone near the augmentation site. The hsCPC is also cytocompatible, and can support bone and stem cell proliferation and differentiation. hsCPC scaffolds stimulated osteogenic gene expression comparable to native bone scaffolds. hsCPC scaffolds are also capable of delivering drug for up to 4 weeks, in vitro. Finally, a cement additive, pyrophosphate, stimulated differentiation, but not proliferation of bone cells.
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Gillespie, Paul Andrew. "Silicon complexes in silicon doped calcium phosphate biomaterials." Thesis, 2007. http://hdl.handle.net/1974/965.
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The silicon complexes in silicon doped calcium phosphate bioceramics have been studied using $^{29}$Si magic angle spinning nuclear magnetic resonance spectroscopy. The replacement of phosphorus by silicon in these materials requires a charge compensation mechanism which is difficult to study by many experimental techniques due to the small amount of silicon added. Producing these materials using an isotopically enriched source of silicon made the use of NMR spectroscopy feasible. Three different materials have been studied: a multiphase material commercially available under the trade name Skelite$^{\rm TM}$ composed of predominantly a silicon stabilized $\alpha$-tricalcium phosphate ($\alpha$-TCP) phase as well as a silicon doped hydroxyapatite (HA) phase, a single phase Si-HA material and a single phase silicon stabilized $\alpha$-TCP material. Slight changes to the material production method were first introduced to accommodate the switch to an isotopically enriched silicon source. Characterization of the enriched materials was carried out using Rietveld refinement of X-ray powder diffraction spectra and X-ray fluorescence spectroscopy to confirm that these materials were similar to the previously studied, non-enriched, materials in terms of the silicon contents, Ca/(P+Si) molar ratios and lattice parameters. NMR Spectroscopy showed that in all three materials, the silicon formed Q$^1$ structures in which two silicate tetrahedra joined together by sharing an oxygen, creating an oxygen vacancy which compensated the substitution of two silicon for phosphorus. This is the first observation of this charge compensation mechanism in Si-HA and may explain the interesting phase evolution previously found in the system studied in this work in which the Si-HA transforms to silicon stabilized $\alpha$-TCP upon sintering.Thesis (Master, Physics, Engineering Physics and Astronomy) -- Queen's University, 2007-12-18 14:45:38.721
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"Synthesis and control of microstructure, mechanical properties, and bioactivity in biphasic and preferentially oriented calcium phosphate bioceramics." THE UNIVERSITY OF ALABAMA AT BIRMINGHAM, 2008. http://pqdtopen.proquest.com/#viewpdf?dispub=3273198.
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Dong, Guo-Chung, and 董國忠. "A Study of Immobilization of Bone Growth Factor on Calcium Phosphate Bioceramics as a Viable Bone Substitute." Thesis, 2002. http://ndltd.ncl.edu.tw/handle/14349602003207805420.
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Despang, Florian. "Hydroxylapatit-Verbundwerkstoffe und -Biokeramiken mit parallel orientierten Porenkanälen für das Tissue Engineering von Knochen." Doctoral thesis, 2012. https://tud.qucosa.de/id/qucosa%3A26966.
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Für das Tissue Engineering von Knochen werden poröse dreidimensionale Substrate (Scaffolds) als Zellträger benötigt, die in der vorliegenden Arbeit über keramische Technologie hergestellt wurden. Neben dem strukturierten und getrockneten Verbundwerkstoff (Grünkörper) und der Sinterkeramik wurde auch der Zwischenzustand nach Ausheizen der organischen Phase (Braunkörper) evaluiert. Bei der Herstellung blieb die Architektur der parallel orientierten Kanalporen, die über den Sol-Gel-Prozess der gerichteten ionotropen Gelbildung des Alginates erzeugt wurde, in allen Materialzuständen erhalten.
Die Herstellungstechnologie wurde derart optimiert, dass die neuartigen anisotropen Scaffolds allen prinzipiell gestellten Forderungen für das Tissue Engineering entsprachen – sie waren porös mit weithin einstellbarer Porengröße, sterilisierbar, gut handhabbar unter Zellkulturbedingungen, biokompatibel und degradabel. Der unerwartete Favorit der Biomaterialentwicklung, der Braunkörper – eine nanokristalline, poröse Hydroxylapatit-Biokeramik – lag in einer ersten in vivo-Studie nach 4 Wochen integriert im Knochen vor. Die beobachtete Knochenneubildung deutete auf eine osteokonduktive Wirkung des Materials hin.
Die in der vorliegenden Arbeit untersuchten Technologien und Biomaterialien bieten eine Basis für weitere Forschung und motivieren zur Weiterentwicklung und Nutzung als Scaffold für das Tissue Engineering oder Knochenersatzmaterial unter Verwendung der interessanten Architektur.
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Brasseale, Beau J. (Beau John) 1980. "An In-Vitro Comparison of Microleakage With E. faecalis In Teeth With Root-End Fillings of Proroot MTA and Brasseler's EndoSequence Root Repair Putty." Thesis, 2011. http://hdl.handle.net/1805/2707.
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Indiana University-Purdue University Indianapolis (IUPUI)Brasseler USA (Savannah, GA) developed and introduced a bioceramic putty called EndoSequence Root Repair Material (ERRM) that can be used as a retrofilling material for surgical endodontics. The material is said to have many of the same chemical, physical, and biological properties as mineral trioxide aggregate (MTA), but with superior handling characteristics. The material is composed of calcium silicates, monobasic calcium phosphate, zirconium oxide, tantalum oxide, proprietary fillers, and thickening agents. ERRM is said by the manufacturer to bond to adjacent dentin, have no shrinkage, be highly biocompatible, hydrophilic, radiopaque, and antibacterial due to a high pH during setting. Investigations on the sealing properties of this material have not yet been conducted. The purpose of this study was to compare the microbial leakage of Enterococcus faecalis in teeth with root-end fillings using ProRoot MTA and Brasseler’s ERRM in a dual-chamber bacterial leakage model as described by Torabinejad and colleagues. The aim of this investigation was to compare the bacterial microleakage of these two root-end filling materials exists. Sixty-two human, single-rooted, mandibular premolars in which extraction was indicated were accessed and instrumented in an orthograde fashion with hand and rotary files. Root resection of the apical 3 mm was then completed and root-end retropreparations were created for placement of root-end filling material. Twenty-seven of these premolars had root-end fillings using ProRoot MTA and 27 had root-end fillings using ERRM. Two teeth were used as a positive control group with no root-end filling, and two other teeth were used as a negative control group and were sealed and coated with dentin bonding agent. The teeth were then evaluated for microleakage using a dual-chamber bacterial microleakage model for 40 days as described by Torabinejad and colleagues. Microleakage was determined by the presence of turbidity in the lower chamber of the apparatus and was assessed each day. Fresh samples of E. faecalis were used every three days to inoculate the apparatus and serve as a bacterial challenge for the materials. Results were recorded every day for 30 days. The outcome of interest (bacterial turbidity) and time-to-leakage (in days) were determined for each of the samples. Survival analysis was used to compare the two groups with a Kaplan-Meier plot to visualize the results and a nonparametric log-rank test for the group comparison. The microleakage of ERRM was not statistically different (p > 0.05) than leakage of ProRoot MTA when subjected to E. faecalis over the 40 day observation period. Both groups had a small number of early failures (within 4 days) and no leakage was observed for the remaining 40 days of the study. Therefore, the null hypothesis was rejected. The results of this research support the use of either of these two materials when compared with the controls. The microleakage of Brasseler’s EndoSequence Root Repair Material was at least as good as ProRoot Mineral Trioxide Aggregate when tested with E. faecalis.