In vitro behaviour of Nurse's Ass-phase: A new calcium silicophosphate ceramic

In the present study, a new single phase Si-Ca-P-based ceramic (called Nurse's Ass) was obtained and its in vitro behaviour was explored for potential bone tissue regeneration. A porous Si-Ca-P single phase ceramic was obtained from high-temperature sintering of previously synthesised γ-dicalcium silicate and β-tricalcium phosphate. Apatite-mineralisation ability and the dissolution rate were systematically studied by immersing the material in simulated body fluid (SBF) for several time points. Massive new dense calcium deficient hydroxyapatite (CDHA) layer formation was observed at the SBF-sample interface. Adjacent to the dense CDHA layer, a porous structure developed parallel to the interface, formed by the pseudomorphic transformation of Si-Ca-P (Nurse's Ass) into CDHA. The cell attachment test showed that the new material supported adult human bone marrow-derived mesenchymal stem cells (hMSCs) adhesion and spreading, and cells came into close contact with the ceramic surface during an extended 28-day culture. These findings indicate that the new calcium silicophosphate ceramic possesses good bioactivity and biocompatibility, and might be a promising bone graft substitute.