Nanoporous surface topography enhances bone cell differentiation on Ti-6Al-7Nb alloy in bone implant applications

V-free Ti alloys are viewed as a promising alternative to biomedical Ti-Al-V alloys in bone implant applications. However, the biological response to these alloys depends heavily on the surface characteristics of the implant as well as on the choice of material. This study treated Ti-6Al-7Nb alloys with electrochemical anodization in an alkaline solution for the creation of a thin nanoporous layer (<100 nm in thickness) to improve bone cell differentiation. The resulting hydrophilic surface nanotopography resulted in anodized Ti-6Al-7Nb alloy with pores 10-100 nm. Compared to untreated alloys, the proposed surface treatment was shown to enhance the blood responses, alkaline phosphatase activity, mineralization, and expression of Runx2 transcription factor and various osteogenic markers, including the gene and protein expression of osteopontin, osteocalcin, bone sialoprotein, and type I collagen, from human bone marrow mesenchymal stem cells. The increased expression of osteogenic markers is expected to promote in vivo osseointegration on Ti-6Al-7Nb alloy in bone implant applications. This might be the first report on the enhancement of osteogenic gene and protein expressions on Ti-6Al-7Nb alloy through rapid formation of hydrophilic surface nanotopography.