Deposição de revestimento bioativo em Titânio por oxidação eletrolítica com Plasma
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Data
2018-09-12
Autores
Antônio, César Augusto
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Editor
Universidade Estadual Paulista (Unesp)
Resumo
O titânio e suas ligas, embora sejam biocompatíveis, não promovem o processo de diferenciação celular. Em consequência disto, diversas técnicas são empregadas para melhorar este requisito, como por exemplo, o recobrimento de sua superfície por uma camada de fosfato de cálcio, tal como a hidroxiapatita (HA). Porém processos atuais de deposição de fosfato necessitam de longos períodos de tratamento, elevadas temperaturas de deposição e posteriores tratamentos térmicos para cristalização do fosfato de cálcio, transformando-o em HA. Neste estudo, a técnica de Oxidação Eletrolítica com Plasmas (PEO) foi empregada para se depositar, sobre titânio Grau 4, revestimentos com altas concentrações de hidroxiapatita, em curtos períodos de tempos, sem a necessidade de pré ou pós-tratamentos. Também foi produzida HA dopada com magnésio, um importante nutriente para diferenciação celular, em uma única etapa de tratamento. Utilizou-se a técnica de difração de raios X (DRX) com Refinamento de Rietveld para identificar e quantificar as fases cristalinas presentes e a composição química dos revestimentos foi determinada empregando as espectroscopias de retro espalhamento Rutherford (RBS) e de energia dispersiva de raios X (EDS). A rugosidade e a morfologia das superfícies foram avaliadas por perfilometria e microscopia eletrônica de varredura (MEV), respectivamente. A difração de raios X revelou que foram depositados revestimentos com até 83,5% de HA e até 73,5% de HA dopada com Mg. Os resultados de adesão, proliferação e diferenciação celulares, por Fosfatase Alcalina, revelaram que os revestimentos contendo HA promoveram um aumento de até 43% na diferenciação celular, em comparação com o titânio sem tratamento.
ABSTRACT Although titanium and its alloys are biocompatible, they do not promote cell differentiation. As a consequence, various techniques are employed to improve this requirement. In this sense, one of the most important approach is the coating of its surface by a layer of calcium phosphate, such as hydroxyapatite (HA). However, current phosphate deposition processes require long treatment time, high deposition temperatures and subsequent thermal treatments for crystallization of calcium phosphate, transforming it into HA. In this study, Plasma Electrolytic Oxidation (PEO) technique has been used to deposit, on Grade 4-Titanium samples, coatings with high concentrations of hydroxyapatite, in short periods of time, without the need for pre or post treatments. Furthermore, magnesium, an important nutrient for cell differentiation, was incorporated in HA coatings in a single treatment step. X-ray diffraction (XRD) with Rietveld refinement was used to identify and quantify the crystalline phases. The chemical composition of the coatings was determined using Rutherford backscattering (RBS) and X-ray dispersive energy (EDS) spectroscopies. Surface roughness and morphology were evaluated by profilometry and scanning electron microscopy (SEM), respectively. X-ray diffraction revealed that some coatings contained up to 83.5% HA and up to 73.5% Mg doped HA. Cell adhesion, proliferation and differentiation results, by Alkaline Phosphatase, revealed that HA-containing coatings promoted an increase in up to 43% in cell differentiation compared to untreated titanium.
ABSTRACT Although titanium and its alloys are biocompatible, they do not promote cell differentiation. As a consequence, various techniques are employed to improve this requirement. In this sense, one of the most important approach is the coating of its surface by a layer of calcium phosphate, such as hydroxyapatite (HA). However, current phosphate deposition processes require long treatment time, high deposition temperatures and subsequent thermal treatments for crystallization of calcium phosphate, transforming it into HA. In this study, Plasma Electrolytic Oxidation (PEO) technique has been used to deposit, on Grade 4-Titanium samples, coatings with high concentrations of hydroxyapatite, in short periods of time, without the need for pre or post treatments. Furthermore, magnesium, an important nutrient for cell differentiation, was incorporated in HA coatings in a single treatment step. X-ray diffraction (XRD) with Rietveld refinement was used to identify and quantify the crystalline phases. The chemical composition of the coatings was determined using Rutherford backscattering (RBS) and X-ray dispersive energy (EDS) spectroscopies. Surface roughness and morphology were evaluated by profilometry and scanning electron microscopy (SEM), respectively. X-ray diffraction revealed that some coatings contained up to 83.5% HA and up to 73.5% Mg doped HA. Cell adhesion, proliferation and differentiation results, by Alkaline Phosphatase, revealed that HA-containing coatings promoted an increase in up to 43% in cell differentiation compared to untreated titanium.
Descrição
Palavras-chave
Hidroxiapatita, Oxidação eletrolítica com plasma, Titânio, Revestimento bioativo, Hydroxyapatite, Plasmas electrolytic oxidation, Titanium, Bioactive coating