Osteoinductive and bioactive scaffolds with modulation of superficial morphology and high mechanical resistance (around 1.8 MPa) have been obtained. These novel scaffolds are made up of a multi-layered ceramic core of wollastonite (CaSiO₃) coated with a glass of composition Ca₂P₆O₁₇. The core was coated with tricalcium phosphate (TCP) and wollastonite, doped with Na, K and Mg (ion 1.35 to 2.7 molar %) promoting the precipitation of hydroxyapatite (HA) with the morphology of agglomerated spheres with multiple channels.Scaffolds were obtained using the Sol-Gel method in combination with the polymeric sponge replication technique. In vitro bioactivity was analyzed by immersing the scaffolds in simulated body fluid (SBF) for different times following the guidelines of the ISO 23317-2014. Samples were characterized by X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM) and Inductively Coupled Plasma Atomic Emission Spectroscopy (ICP-OES).

Results showed that after 3 days immersed in SBF, HA spheres of 1-2 μm has been precipitate. These are composed of HA of low crystallinity and square morphology [2,3]. After 7 days, larger spheres (8-9 μm) with acicular HA creating a compact mantle are observed, indicating an increase in crystallinity. Additionally, ionic drainage channels appear, possibly due to the presence of magnesium, which increases the instability of the initially precipitated HA, causing its dissolution and subsequent reprecipitation. As seen at day 14, the crystallinity of the HA increases as well as the density of the ionic drainage channels, thus increasing the mesoporosity of the structure. This behaviour potentially allows the storage of drugs and other bioactive molecules inside the structure for their controlled release over time.

References

[1] L. Zhang et al.;Acta Biomaterialia,2019, 84, 16–33

[2] E. Sebastián et al.; Ceramics International, 2023, 49(3), 4393–4402.

[3] C. Berg et al.; Ceramics International, 2019, 45(8), 10385–10393.