Bioactive surface modification of Ti–Nb alloy by alkaline treatment in potassium hydroxide solution

Abstract The aim of this work is to compare the responsive behaviour of titanium, niobium and titanium–niobium alloy during alkaline treatment in forming alkaline titanate layer and their resultant bioactive properties. Titanium and niobium powder mixture with composition in the beta region was pressed at 550 MPa and sintered at 1,200 °C for 2 h. The alloy was soaked in potassium hydroxide aqueous solution at 60 °C for 24 h with different concentrations of 0.5 M and 5 M. The effect of post sintering-heat treatment was investigated by annealing the treated alloy at 600 °C for 2 h. X-ray diffraction analysis and Fourier transform infrared spectroscopy analysis were used to evaluate the chemical composition and the functional group of material on the treated alloy surface respectively. Immersion in Hanks solution for 1 day resulted in traces of calcium and phosphate on alloy surfaces treated in different concentrations of alkali as well as post-heat treatment. The cell viability evaluation using MTT (3-[4,5-dimethylthiazol-2-yl]-2,5 diphenyl tetrazolium bromide) assay on the new beta-Ti alloy with potassium-based titanate layer demonstrated potassium hydroxide treatment with a 5 M concentration after post-heat treatment significantly improved cell proliferation, which is a prerequisite for bone mineral apatite deposition.