Titanium (Ti) is frequently used as a biomaterial in dental and orthopedic implants and in bone fixation devices. Effective modification of the Ti surface plays a crucial role in improving biocompatibility. Carbon nanotubes (CNTs) are among the most interesting nanomaterials due to their unique properties. In this study, we fabricated CNT-Ti composite surfaces by annealing Ti plates covered by different sized CNTs (Nanocyl NC 7000, 9.5 nm diameter and VGCF-H, 150 nm diameter). The properties of these surfaces were examined by scanning electron microscopy, X-ray diffraction, energy dispersive X-ray spectroscopy, raman spectroscopy, contact angle measurement and osteoblast-like cell seeding. In addition, samples were implanted into the subcutaneous tissue of rats. The three-dimensional nanostructures of CNTs and creation of titanium carbide were evident on the Ti surfaces, suggesting that the CNTs were well-anchored onto the Ti plates. CNT modification promoted desirable cell behavior, including cell spreading and proliferation, especially on the Nanocyl-modified surface. Inflammatory response was rarely observed on the Nanocyl surface, but macrophage-like giant cells were frequently observed on the VGCF-H surface. Therefore, the nanomorphology of narrow diameter CNTs provides a CNT-Ti composite surface with good biocompatibility
