Bioactivity tests in vitro of Ti-Nb alloys

Abstract

Event Abstract Back to Event Bioactivity tests in vitro of Ti-Nb alloys Douglas Valerio1, Pedro A. Bazaglia2, Carlos M. Lepienski3, Carlos R. Grandini2 and Neide K. Kuromoto1, 3 1 Universidade Federal do Paraná, Physics Department, Brazil 2 Universidade Estadual Paulista, Laboratório de Anelasticidade e Biomateriais, Brazil 3 Universidade Federal do Paraná, Graduate Program in Materials Science and Engineering, Brazil Introduction: The mostly used alloy to manufacture orthopedic implant is the Ti-4V-6Al, due to its good mechanical property and well know biocompatibility, however, there is a certain lack of consent regarding to the cytotoxic of the aluminum present in the alloy. Some authors claim that the aluminum ions released in a bone-implant situation could lead to some long term harmful effects [1]. An alternative to the Ti-4V-6Al are the Ti-Nb alloys. The addition of Nb allows the production of a material with high corrosion resistance rate and a lower elastic modulus (E) than the original titanium, this effect is due the stabilization of the phase of Ti, which has lesser E than the phase. Furthermore, is well stated that anodization can improve both mechanical and bioactivity/biocompatibility properties in metallic biomaterials, thus the objective of this work is to oxidize Ti-Nb alloys to obtain bioactive surfaces and to evaluate the bioactivity in vitro of the these surfaces using simulated body fluid . Materials and methods: The precursor materials used were commercially pure titanium grade 2 (cp-Ti) with 99.7% purity and niobium (Nb) with 99.8% purity. Titanium niobium alloys were obtained using an arc melting furnace on argon-controlled atmosphere, with a weight percentage of 10 and 20 wt. (%) of Nb. Small disks with (9x2) mm were obtained from the ingots, that were abraded with SiC paper, polished with colloidal silica in suspension then ultrasonically cleaned in acetone, isopropyl alcohol and deionized water and finally, dried at 40 °C for 24h. The alloys surfaces were chemically etched to analyze the microstructure of each one. The anodic films were obtained using anodic oxidation technique (AO) in 1.0 ML-1 H3PO4 electrolyte, using voltage of 250V during 60s. A platinum sheet was used as a counter-electrode. The surface bioactivity in vitro were evaluated using simulated body solution (SBF) developed by Kokubo et col [2]. The samples were soaked in SBF during 30 days at 37oC. After that the surfaces were analyzed using scanning electron microscope (SEM) and Raman spectroscopy. Results and Discussion: Figures 1a-b show the morphologies of the anodized Ti-Nb alloys surfaces, the round porous results of the dielectric breakdown. After the bioactivity tests a new layer appears on the Ti10Nb oxidized surface (fig. 2a) and a few round aggregates on the surface with Ti20%Nb (fig. 2c). The EDS analysis indicate the presence of the elements Ca and P besides Ti and O (fig. 2b and 2d) indicating that the layer observed on the Ti10%Nb as apatite. The Raman spectroscopy analysis shows the presence of the apatite layer on the Ti-10% Nb alloy after 30 days in SBF, in accordance with SEM analysis. The lack of apatite layer on the oxidized Ti-20Nb could be caused by the higher proportion of Nb. Conclusion: The anodic oxidation technique was adequate to obtain bioactive surface. The apatite layer was observed on the alloy Ti-10%Nb after immersion in SBF. CME; CNPq; LabNano