Effect of Human Serum Proteins on Pure Hydroxyapatite and Silicon Substituted Hydroxyapatatite: AFM and SEM Studies

Human serum proteins adhere to calcium phosphate within seconds after implantation. This layer influences the biological behaviour of the biomaterials. Hydroxyapatite (HA) and 0.8 wt% of silicon substituted hydroxyapatite (Si-HA) were incubated in three different solutions; simulated body fluid, simulated body fluid with 0.1% and 10% in volume of human serum. The surface of Si-HA underwent significant surface changes more rapidly than the HA surface. After a period of 7 days incubation in SBF an apatite layer was observed by ESEM and AFM on the Si-HA surface, but not on the HA surface. At the HA surface calcium phosphate deposits were only observed after 28 days of incubation. The formation of an apatite layer on the surface of both materials seems to have been delayed with the addition of human serum proteins.