Electrochemical corrosion behaviors of novel beta titanium alloys, Ti-30Ta-10Nb-10Zr, Ti-40Ta-10Nb-10Zr and Ti40Ta-10Nb-4Sn were characterized in naturally aerated Hank's solution at 37 o C compared with currently used biomedical titanium alloys. Ti-30Ta-10Nb-10Zr and Ti-40Ta-10Nb-10Zr exhibited comparable corrosion resistance to CP Ti or Ti-6Al-4V, while the corrosion resistance of Ti-40Ta-10Nb-4Sn was greatly inferior to the other alloys. An EIS data analysis confirmed that the resistance of passive film for Ti-30Ta-10Nb-10Zr and Ti-40Ta-10Nb-10Zr was comparable to CP Ti or Ti-6Al-4V. Ti-30Ta-10Nb-10Zr and Ti-40Ta-10Nb-10Zr alloys are promising metallic biomaterials for the future, owing to their very low elastic modulus and good corrosion resistance capabilities.

The effect of niobium and tantalum on the elastic modulus and the in vitro biocompatibility in binary titanium alloys was studied. The Young's modulus of titanium was effectively lowered with additions of Nb or Ta, depending significantly upon the microstructure. Martensitic microstructures such as D' and D" decreased the elastic modulus, while the Z phase increased it. Ti-10 %Nb, Ti-30 %Nb and Ti-30 %Ta alloys exhibited very low elastic moduli of 74, 80, and 58 GPa, respectively. The corrosion resistance of Ti-xTa was slightly higher than that of Ti-xNb, which was comparable to that of CP Ti or Ti-6A-4V. No ion release was detected in Hank's solution, while Ti ions were released in 0.1 % lactic acid ranging from 0.03 to 0.11 Pg/ml for both the Ti-xNb and Ti-xTa alloys. MG63 osteoblast-like cell proliferation on Ti-30 %Ta was less active compared with Ti-30 %Nb, CP Ti or Ti-6Al-4V.

New titanium alloys with a low elastic modulus have been developed for biomedical applications to avoid the stress shielding effect of an artificial prosthesis. The newly developed alloys contained the transition elements like Zr, Hf, Nb, Ta which were non-cytotoxicity elements and β stabilizers. In the present paper the elastic moduli of Ti-xM containing Zr, Hf, Nb, Ta were evaluated by measuring the velocity of supersonic wave (Pulse Echo Overlap). The effectiveness of the alloying elements for lowering the elastic modulus was investigated. In addition, the dominant factors for the low modulus were discussed. Ta was the most effective in lowering the elastic modulus of the alloys. The effectiveness of Hf was not acceptable for decreasing the elastic modulus. The dominant factor was the lattice parameter for Zr, and the poisson's ratio for Nb, Ta, respectively, in lowering the elastic modulus of Ti.

Poly ε-caprolactone(PCL)/hydroxyapatite(HA) composite scaffolds were fabricated by particulate leaching and freeze drying routes with different HA content. Porosity was decreased with HA addition, while mean pore size was maintained at around porogen size regardless of HA content. Compressive modulus was increased with increasing HA content. In this study, the optimum content of HA was around 40% in weight against PCL to obtain the highest compressive modulus with keeping porosity above 85%. HA apparently enhanced proliferation of osteoblast-like MG63 cells in PCL/HA composite scaffolds. Typical adhesion, migration and aggregation procedure of MG63 cells were found on PCL, while spreading morphology only was found on HA even at the early stage of adhesion without migration or aggregation.

New titanium alloys with a low elastic modulus have been developed for biomedical applications to avoid the stress shielding effect of the artificial prosthesis. The newly developed alloys contained the transition elements like Nb, Ta, Zr which were non-cytotoxicity elements. These elements produced β, ω, and α'' phases with heat treatment conditions in titanium alloys and determined the elastic modulus of the alloys. However, the clear mechanism of the low elastic modulus alloys has not been known. In the present paper, the total energy and elastic modulus of β and α'' phases were calculated using a first principle calculation employing the generalized gradient approximation (GGA). The mechanism of the low elastic modulus was discussed with calculated values.