Porous Titanium Treated by Nitric Acid with Varied Concentration and the Bioactivity in Vitro

Surface modification is expected to further activate the titanium implant and has been widely used in dense titanium surface. In this study, porous titanium fabricated by a slurry foaming method was treated by nitric acid solution with different concentrations. Micrometer-sized acid-etched pits were observed on the inner-pore walls of porous titanium and the morphology varied a little with nitric acid concentration. However, the ability to deposit apatite on the treated porous titanium surface changed obviously with nitric acid concentration. The samples treated by nitric acid solution at a ratio of 1:1 and 1:5 (V(HNO 3 ):V(H 2 O)) showed the best apatite-forming ability. Compared with that non-treated porous titanium, the samples were treated by nitric acid at the ration of 1:1 and 1:5 (V(HNO 3 ):V(H 2 O)) showed higher MG63s cells viability, better cells adhesion and spreading with cells both on the surface and inside the pores. The results showed that nitric acid treatment, a simple process with less impurity introduced and good penetration inside porous titanium was an effective method to prepare bioactive porous titanium.