Influence of nanometer smoothness and fibronectin immobilization of titanium surface on MC3T3-E1 cell behavior

The aim of the present study was to evaluate the influence of mechanical treatment, namely, nanometer smoothing (Ra: approximately 2.0 nm) and sandblasting (Ra: approximately 1.0 μm), as well as biochemical treatment, namely, fibronectin immobilization, of a titanium surface on osteoblast-like cell behavior. Cell proliferation was monitored by measurements of DNA content and ALP activity; osteocalcin production and mineralization behavior were also evaluated, in addition to morphological observation of attached cells. Fibronectin could be immobilized by the tresyl chloride-activation method. A sandblasted surface resulted in significantly more DNA than a nanometer-smooth surface, but fibronectin immobilization did not result in a significant increase of DNA at 52 days of cell culture. The nanometer-smooth surface showed highest ALP activity and osteocalcin production. FN immobilization decreased ALP activity for the nanometer-smooth surface, but increased it for the sandblasted surface. The nanometer-smooth surface also showed the highest osteocalcin production. Scanning electron microscopy showed interesting phenomena of the attached cells. Attached cell area was more rapidly increased on the nanometer-smooth surface than on the sandblasted surface. It was suggested that cultured cells on the nanometer-smooth surface began to spread earlier and that the proportion of spreading cells among total attached cells increased sooner on the nanometer-smooth surface than on the sandblasted rough surface. It appeared that FN immobilization influenced the arrangement of attached cells. In conclusion, the nanometer-smooth surface employed in the present study was beneficial for the differentiation of MC3T3-E1 cells. FN immobilization influenced the morphologies of attached cells.