Identification of Proteins Adsorbed on Hydroxyapatite Ceramics with a Preferred Orientation to a-Plane

Protein adsorption is essential for determining material biocompatibility and promoting adherent cell growth. In this study, we focused on the a-plane structure of hydroxyapatite (HAp). This a-plane structure closely resembles the crystal plane where apatite is exposed in long bones. We conducted protein adsorption experiments using HAp ceramics with a preferred orientation to a-planes (aHAp), employing bovine serum albumin (BSA), lysozyme, and fetal bovine serum (FBS) as protein models to mimic the in vivo environment. Higher zeta potential and contact angle values were found in aHAp than in HAp ceramics fabricated from commercial HAp powder (iHAp). Bradford-quantified protein adsorption revealed BSA adsorption of 212 ng center dot mm(-2) in aHAp and 28.4 ng mm(-2) in iHAp. Furthermore, the Bradford-quantified protein adsorption values for FBS were 2.07 mu g mm(-2) in aHAp and 1.28 mu g mm(-2) in iHAp. Two-dimensional electrophoresis (2D-PAGE) showed a higher number of protein-derived major spots in aHAp (37 spots) than in iHAp (12 spots). Mass spectrometry analysis of the resulting 2D-PAGE gels revealed proteins adsorbed on aHAp, including secreted frizzled-related protein 3 and vitamin K epoxide reductase complex 1, which are involved in cellular bone differentiation. Overall, these proteins are expected to promote bone differentiation, representing a characteristic property of aHAp.

Automated summary

Protein adsorption is crucial for material biocompatibility and cell growth. This study focused on the a-plane structure of hydroxyapatite (HAp) and found that it has a strong protein adsorption ability, particularly proteins related to cellular bone differentiation.