Silica‐Based Bioceramic Scaffold for Bone Regeneration: Microstructural Study, Phase Evolution, and Bioactivity

Abstract

In this study we present a bioceramic scaffold with potential interest in bone regeneration. It was successfully produced using the well-known and reproducible method of solid state reaction (SSR), with the composition 36SiO2, 22Na2O, 32CaO and 10P2O5 in wt%. Two crystalline phases were found in the bioceramic scaffold, Na2Ca2Si3O9 and CaNaPO4. Moreover, during thermal cycling, it was possible to identify a peculiar exothermic peak through DTA and in-situ XRD, which corresponded to a martensitic or diffusionless transformation. This transformation was found to be reversible through an in situ X-ray experiment, along heating and cooling cycles between 600 and 700°C. The nanoporosity was observed with a TEM, and the macroporostity was evaluated by SEM and micro-CT, obtaining an open porosity of 64 %. Heterogeneous elemental composition was evaluated by EDS studies. In vitro bioactivity tests showed the formation of hydroxycarbonate apatite (HCA) crystals that cover all the bioceramic scaffold after immersion in the simulated body fluid, thereby indicating its bioactivity. Compressive mechanical tests were performed on scaffold samples, both with and without HCA on their surface, obtaining compression resistance values of 0,70 ± 0,09 MPa and 0,51 ± 0,03 MPa respectively, values comparable to those of cancellous bone.