Proteomic analysis of bone proteins adsorbed onto the surface of titanium dioxide.

Osseointegration is the structural and functional connection between bone tissues and implants such as titanium dioxide (TiO). The bone-TiO interface is thought to contain proteoglycans. However, exhaustive analysis of the proteins in this layer has not been performed. In this study, we evaluated the bone protein adhered on the surface of TiO comprehensively. Pig bone protein was extracted by sequential elutions with guanidine, 0.1 M EDTA, and again with guanidine. The proteins obtained from these extractions were allowed to adhere to an HPLC column packed with TiO and were eluted with 0.2 M NaOH. The eluted proteins were identified by LC/MS/MS and included not only proteoglycans but also other proteins such as extracellular matrix proteins, enzymes, and growth factors. Calcium depositions were observed on TiO particles incubated with bone proteins, guanidine-extracted proteins adhered to TiO displayed significantly high amounts of calcium depositions.