Specific proteins mediate enhanced osteoblast adhesion on nanophase ceramics

Osteoblast, fibroblast, and endothelial cell adhesion on nanophase (that is, materials with grain sizes less than 100 nm) alumina, titania, and hydroxyapatite (HA) was investigated using in vitro cellular models. Osteoblast adhesion was significantly (p < 0.01) greater after 4 h on nanophase alumina, titania, and HA than it was on conventional formulations of the same ceramics. In contrast, compared to conventional alumina, titania, and HA, after 4 h fibroblast adhesion was significantly (p < 0.01) less on nanophase ceramics. Examination of the underlying mechanism(s) of cell adhesion on nanophase ceramics revealed that these ceramics adsorbed significantly (p < 0.01) greater quantities of vitronectin, which, subsequently, may have contributed to the observed select enhanced adhesion of osteoblasts. Select enhanced osteoblast adhesion was independent of surface chemistry and material phase but was dependent on the surface topography (specifically on grain and pore size) of nanophase ceramics. The capability of synthesizing and processing nanomaterials with tailored (through, for example, specific grain and pore size) structures and topographies to control select subsequent cell functions provides the possibility of designing the novel proactive biomaterials (that is, materials that elicit specific, timely, and desirable responses from surrounding cells and tissues) necessary for improved implant efficacy. (C) 2000 John Wiley and Sons, Inc.