Pereira Bruno Leandro, Lepienski Carlos Maurício, Mazzaro Irineu, Kuromoto Neide Kazue
Universidade Federal do Paraná, Programa de Pós-Graduação em Engenharia e Ciência dos Materiais - PIPE, Curitiba, PR, Brazil.
Universidade Federal do Paraná, Programa de Pós-Graduação em Engenharia e Ciência dos Materiais - PIPE, Curitiba, PR, Brazil; Pontifícia Universidade Católica do Paraná, Programa de Pós-Graduação em Engenharia Mecânica - PPGEM, Curitiba, PR, Brazil.
Mater Sci Eng C Mater Biol Appl. 2017 Aug 1;77:1235-1241. doi: 10.1016/j.msec.2016.10.073. Epub 2016 Oct 31.
Plasma electrolytic oxidation (PEO) of niobium plates were done electrochemically in two steps with electrolytes containing phosphorous and calcium being observed the formation of crystalline apatite. All samples were submitted to a first step of PEO using an electrolyte containing phosphate ions. The second oxidization step was made using three different electrolytes. Some samples were oxidized by PEO in electrolyte containing calcium, while in other samples it was used two mixtures of phosphoric acid and calcium acetate monohydrate solutions. Three different surface layers were obtained. The morphology and chemical composition of the films were analyzed by scanning electronic microscopy (SEM), and energy dispersive spectroscopy (EDS) respectively. It was observed that all samples submitted to two-step oxidation shown porous surface and a calcium and phosphorus rich layer. Average surface roughness (Ra) was measured by a profilometer remaining in the sub-micrometric range. The contact angle by sessile drop technique, using 1μL of distilled water was performed with an optical goniometer. It was verified a higher hydrophilicity in all surfaces compared to the polished niobium. Orthorhombic NbO was identified by XRD in the oxide layer. Crystalline apatite was identified by XRD in surfaces after the second oxidation made with the Ca-rich electrolyte and a mixture of an electrolyte richer in Ca compared to P. These results indicate that a two-step oxidized niobium surface present great features for applications in the osseointegration processes: favorable chemical composition that increase the biocompatibility, the formation of crystalline niobium pentoxide (orthorhombic), high hydrophilicity and formation of crystalline calcium phosphate (apatite) under adequate electrolyte composition.
铌板的等离子体电解氧化（PEO）通过两步电化学法进行，在含有磷和钙的电解质中观察到了结晶磷灰石的形成。所有样品首先使用含磷酸根离子的电解质进行PEO第一步处理。第二步氧化使用三种不同的电解质。一些样品在含钙的电解质中通过PEO氧化，而其他样品则使用磷酸和一水合醋酸钙溶液的两种混合物。获得了三种不同的表面层。分别通过扫描电子显微镜（SEM）和能量色散光谱（EDS）分析了膜的形态和化学成分。观察到所有经过两步氧化的样品都呈现出多孔表面和富含钙和磷的层。通过轮廓仪测量平均表面粗糙度（Ra），其保持在亚微米范围内。使用光学测角仪通过静滴技术，用1μL蒸馏水测量接触角。与抛光铌相比，所有表面的亲水性都更高。通过XRD在氧化层中鉴定出正交晶系的NbO。在用富含钙的电解质以及与磷相比富含钙的电解质混合物进行第二次氧化后的表面，通过XRD鉴定出结晶磷灰石。这些结果表明，两步氧化的铌表面在骨整合过程的应用中具有很大的优势：有利的化学成分增加了生物相容性，形成了结晶五氧化二铌（正交晶系），具有高亲水性以及在适当的电解质组成下形成了结晶磷酸钙（磷灰石）。
