Highly Bioactive 8 nm Hydrothermal TiO2 Nanotubes Elicit Enhanced Bone Cell Response

The TiO(2) passivation layer on the Ti surface has positive bone-interface qualities including bioactivity and chemical composition that aids in the integration of orthopedic implants, known as osseointegration. New research designs have focused on the topographic structure of the TiO(2) oxide layer with a large surface area for optimizing osseointegration properties for improved implant performance. We have utilized a hydrothermal process to further refine the TiO(2) structure to an 8 nm diameter nanotube geometry and evaluated its effect on bone cell growth. Interestingly these small diameter TiO(2) nanotubes, unlike the anodized TiO(2) nanotubes, exhibit mostly multiwalled nanotube configuration with about 2-6 parallel walls along the length of the elongated nanotubes. It has been found that these multiwall nanotubes significantly enhance osteoblast cell response compared to unmodified, control Ti. The nanotube structure provided significantly up-regulated bone forming ability with approximate to 2-3 fold increased alkaline phosphatase (ALP) activity levels, and induced the formation of abundant amounts of bone matrix deposition predominantly consisting of calcium and phosphorous. Biomedical implications of such bone cell and nanotube interface behavior on bone formation and bone bonding of titanium implants are discussed.