Preparation and bioactivity of TiO2 nanotube arrays containing calcium and phosphorus

Abstract

With NH4H2PO4 and NH4F glycerin/water mixed solvent as electrolyte, through the anodic oxidation and calcium hydroxide hydrothermal treatment, TiO2 nanotube arrays containing calcium and phosphorus were prepared. Moreover, the influence of the processing time, titania crystalline phase and pH value of the solution were investigated. And the bioactivity of the nanotube arrays were examined by soaking in simulated body fluid. The results showed that the TiO2 nanotube arrays prepared in the phosphate-containing glycerin system can contain a small amount of phosphorus. When the processing time <0.5h, the nanotube arrays maintained the original tubular structure, but the quantity of Ca element reduces. When the processing time was ≥2h, the original tubular structure of the anatase nanotube arrays was transferred into nano four pillars, and with extending the processing time, the sizes of nano four pillars were slightly increased. But the morphology of the as-prepared nanotube arrays changed very slightly. And a content of Ca element increased with the increase in the hydrothermal treatment time. The existence form of Ca element is calcium titanate. The samples after hydrothermal treatment in saturated Ca(OH)2 solution are clearly more efficient in promoting apatite formation than the as-prepared or anatase nanotube arrays.