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Anodic and nanostructural layers on titanium and its alloys for medical applications

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For the last more than thirty years medical applications of titanium alloys take advantage of their excellent corrosion resistance and biocompability for use as prosthetic and surgical devices. Although poor wear resistance stable oxide layer on titanium alloys prevents any redox reaction between metal and tissue. The extended use of titanium and its alloys, especially in medical and aerospace applications, is due to treatments which enhance properties of oxide surface layer. To obtain corrosion resistant, bioactive and anti-fretting surface for biomedical use, the application of a proper surface finishing treatment like anodizing is necessary [1, 2]. PASSIVATION OF TITANIUM ALLOYS The spontaneous passivation upon exposing titanium to air [3]. In contact with air, native oxide [...]

Investigation for Ti/TiO2 electrode used as a platform for H2O2 biosensing

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Achievements of nanotechnology based on applying of inexpensive materials of the unique properties play an important role in development of biosensors. Such materials and the catalytic activity of biomolecules on their surface, i.e. the modified electrodes such as TiO2, ZrO2, SiO2 coated metals were observed [1]. On the basis of those observations it was found that sensitivity and efficiency of biosensors could be improved by the application of mentioned as the biosensor platform. According to [2], TiO2 became one of the most widely studied semiconductor materials due to its favorable physical, optical and electrical properties and its various important applications, such as a photocatalyst [3÷7], solar cells [8÷10], gas sensors [11÷13] and biomaterials [14]. Titanium dioxide be[...]

Role of phosphates in improvement of surface layer on titanium alloys for medical applications

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Anodic films on titanium alloys have been of great interest due to their industrial applications [1]. However, anodizing can also result in the incorporation of biological species into the oxide layer and then such surface layers are of a great importance for medical purposes [2, 3]. Such layers are not only corrosion resistant, but also biocompatible [2÷4]. Anodizing in phosphate solutions leads to the incorporation of phosphate ions into the oxide layers on titanium and Ti6Al4V influencing their bioactivity and stimulating deposition of the biocompatible hydroxyapatite [5÷8]. Unalloyed titanium is resistant to naturally aerated pure solutions of phosphoric acid up to 30 % wt concentration (~3.6 M), but undergoes corrosion attack at higher concentrations and temperatures [2, 3, 9]. For lower concentrations, up to 3 M, mainly non-dissociated acid molecules and one protonated form H2PO4 - of phosphate ions exist in phosphoric acid solutions [10] and they exhibit strong affinity or complexing power towards most metal cations. The latter may be used to shape properties of titanium implant materials for medical purposes. The effect of anodizing at different polarization conditions in dilute (0.5 M) and concentrated (2 M) phosphoric acid solution is described in this paper. According to the applied anodizing conditions the electrochemical (polarization, impedance) and morphological examinations showed formation of either porous and thin oxide layer [11÷23] or gel-like phosphates rich layer of H3PO4×0.5H2O [11, 24÷29], covering thicker oxide layer on titanium. Formation of self-organized titania nanotubes with high level organization of pores on large surfaces [30÷35] became very useful technology applied to many purposes, i.e. to modification of surgical implant surfaces and to environmental and biomedical sensing. Our efforts were focused on controlling the size and arrangement of pores [36÷42], aiming at bone ingrowth and on use [...]

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