Evaluation of TiO2 nanotubes growth on Ti-Mo alloys for biomedical applications

摘要

Metallic biomaterials have been used tor biomedical applications due to excellent properties. However, although their excellent corrosion resistance these materials can be corrode when inserted into the human body and sometimes ions released can produce undesirable toxicity. Thus, titanium based alloys with nontoxic elements have been studied for these applications such as Ti-7.5Mo Ti-10Mo ,Ti-15Mo, Ti-29Nb-13Ta-4.6Zr and Ti-13Nb-13Zr with better bulk properties. However, the efficacy of osseointegration also is influenced by surface properties including chemical composition, wettability and topography . TiO_2 nanotubes produced by electrochemical anodization have received considerable attention because they are mechanically and chemically stables, biocompatible and aiming the bone formation . Furthermore, titanium oxide nanotubes have potential application in drug delivery due to the control of the length and diameter of the nanotubes.The objective of this study was to evaluate the nanotubes growth on Ti-Mo alloys. Surfaces properties such as morphology, wettability and chemical composition were evaluated. Alloys were produced from sheets of commercially pure titanium (99.9%) and molybdenum (99.9%) according compositions evaluated: Ti-7.SMo and Ti-15Mo. Materials were melted in arc melting furnace under an argon atmosphere. Ingots were cold worked by rotating swage into bars (10 mm of diameter) and discs with 3 mm of thickness were cut. Nanotubes were obtained by using electrochemical anodization and setup consisted as two-electrode configuration with platinum as cathode and alloy as anode was used. The electrolyte solution was glycerol aqueous solution containing 0.25%wt NH_4F. Anodization was performed at applied voltage aoV and 20V for 24 hours at room temperature, the samples were rinsed in deionized water, air dried and annealed at 450°C in air for 1 hour. Surface topography and morphology of nanotubes were evaluated using field emission scanning electron microscopy and the wettability by using contact angle. The oxide layer chemical composition was evaluated by using XPS analysis. Figure 1 shows scanning electron microscope (SEM) images of the nanotubes formed on the surface of the Ti-7.5Mo. The high ordered TiO_2 nanotubes arrays were formed. Ti15Mo exhibited ticker tubes wall for two conditions (Figure 2). For both alloys, a hydrophilic surface was observed after nanotubes growth.