TiO2 nanotubes on Ti: Influence of nanoscale morphology on bone cell-materials interaction

Ti being bioinert shows poor bone cell adhesion with an intervening fibrous capsule. Ti could made bioactive by several methods including growing in situ TiO2 layer on Ti surface TiO2 nanotubes were grown on Ti surface via anodization process and the bone cell-material interactions were evaluated. Human osteoblast cell-attachment and growth behavior were studied using an osteoprecursor cell line for 3, 7, and 11 days. An abundant amount of extracellular matrix (ECM) between the neghboring cells was noticed on anodized nanotube surface with filopodia extensions coming out from cells to grasp the nanoporous surface of the nanotube for anchorage. To better understand and compare cell-materials interactions, anodized nanoporous sample surfaces were etched with different patterns. Preferential cell attachment was noticed on nanotube surface compare to almost no cells in etched Ti surface. Cell adhesion with vinculin adhesive protein showed higher intensity, positive contacts on nanoporous surface and thin focal contacts on the Ti-control. Immuno-chemistry study with alkaline phosphatase showed enhanced osteoblastic phenotype expressions in nanoporous surface. Osteoblast proliferation was significantly higher on anodized nanotube surface. Surface properties changed with the emergence of nanoscale morphology. Higher nanometer scale roughness, low contact angle and hight surface energy in nanoporous surface enhanced the osteoblast-material interactions. Mineraliztion study was done under simulated body fluid (SBF) with ion concentration nearly equal to human blood plasma to understand biomimetic apatite deposition behavior. Although apatite layer formation was noticed on nanotube surface, but it was nonuniform even after 21 day in SBF. (C) 2008 Wiley Periodical, Inc. J Biomed Mater Res 90A: 225-237, 2009