Biological and physical-chemical characterization of phase pure HA and SI-substituted hydroxyapatite by different microscopy techniques

Two different microscopy techniques were used to investigate the response of human osteoblasts to hydroxyapatite (HA) and silicon substituted hydroxyapatite (Si-HA), namely, fluorescence and confocal microscopy The changes in the surface of HA and Si-HA, after incubation for different periods of time in simulated body fluid, were assed using atomic force microscopy and environmental electron scanning microscopy. Cell proliferation was higher on Si-HA compared to HA. In addition more focal points of adhesion were seen in Si-HA than on HA. Using atomic force microscopy and environmental scanning electron microscopy it was possible to observe changes in the surface of both materials, namely dissolution features and the formation of an apatite layer. These findings support the results of a previous study, which showed that Si-HA had a higher dissolution with the preferential release of silicon into the medium and this fact may account for the changes observed in the cell behaviour.