Tomoko Kasuga

Titania Nanotubes Prepared by Chemical Processing

We report a new method for the synthesis of titanium oxide (TiO2) nanotubes. When anatase-phase- or rutile-phase-containing TiO2 was treated with an aqueous solution of 5–10 M NaOH for 20 h at 110 °C and then with HCl aqueous solution and distilled water, needle-shaped TiO2 products were obtained (diameter ≈ 8 nm, length ≈ 100 nm). The needle-shaped products are nanotubes with inner diameters of approximately 5 nm and outer diameters of approximately 8 nm. The formation mechanism of titania nanotubes is discussed in terms of the detailed observation of the products by transmission electron microscopy: the crystalline raw material is first converted to an amorphous product through alkali treatment, and subsequently, titania nanotubes are formed after treatment with distilled water and HCl aqueous solution.

Titanium oxide nanotubes for bone regeneration

Titanium oxide nanotubes with Ca ions on their surfaces were prepared as 2 mm cylindrical inserts and placed into surgically created bone defects in the femurs of Wistar rats. On day 3, fibroblast-like cells were present on the surface of the nanotube inserts and fibers were observed by scanning electron microscopy (SEM). On day 7, cells with alkaline phosphatase activity were present and identified as osteoblasts by SEM and transmission electron microscopy. New bone matrices were observed in and around the porous nanotube inserts by light microscopy. Compared with clinically used hydroxyapatite and tricalcium phosphate, β-titanium oxide nanotubes promote faster acquisition and development of osteoblasts and bone tissues and have better bone regenerating ability after one week.

Synthesis and Properties of Titania Nanotube Doped with Small Amount of Cations

We have investigated a synthesis of metal (Nb, V, Cr, Mn, Co) -doped titania nanotubes using a solution chemical processing in order to control optical and electrical properties. Titania nanotubes doped with a small amount of cations up to 1 wt% exhibited similar morphology and XRD pattern as the pure titania nanotubes, however, color of nanotubes was changed depending on the dopants. It was found that Cr, Mn and Co doped titania nanotubes formed new absorption bands in UV spectra. On the other hand, electrical resistivity of doped titania nanotubes was lower than that of pure titania nanotubes.