Soft tissue response to titanium dioxide nanotube modified implants

Titanium is widely used clinically, yet little is known regarding the effects of modifying its three-dimensional surface geometry at the nanoscale level. In this project we have explored the in vivo response in terms of nitric oxide scavenging and fibrotic capsule formation to nano-modified titanium implant surfaces. We compared titanium dioxide (TiO2) nanotubes with 100 nm diameters fabricated by electrochemical anodization with TiO2 control surfaces. Significantly lower nitric oxide was observed for the nanostructured surface in solution, suggesting that nanotubes break down nitric oxide. To evaluate the soft tissue response in vivo TiO2 nanotube and TiO2 control implants were placed in the rat abdominal wall for 1 and 6 weeks. A reduced fibrotic capsule thickness was observed for the nanotube surfaces for both time points. Significantly lower nitric oxide activity, measured as the presence of nitrotyrosine (P < 0.05), was observed on the nanotube surface after 1 week, indicating that the reactive nitrogen species interaction is of importance. The differences observed between the titanium surfaces may be due to the catalytic properties of TiO2, which are increased by the nanotube structure. These findings may be significant for the interaction between titanium implants in soft tissue as well as bone tissue and provide a mechanism by which to improve future clinical implants.