Synthesis and physicochemical characterization of Zn-doped brushite

Dicalcium phosphate dihydrate (DCPD) enriched by different amounts of Zn2+ ions was synthesised in aqueous solution via standard precipitation method. The obtained powders were characterised by powder X-ray diffractometry (PXRD), infrared spectroscopy (FT-IR), solid-state nuclear magnetic resonance (ssNMR), inductively coupled plasma optical emission spectroscopy (ICP-OES) and scanning electron microscopy (SEM). These tests confirmed that all the powders were highly microcrystalline brushite. As the concentration of zinc increased, an additional crystalline phase of alpha-hopeite appeared, and, simultaneously, the crystallinity of brushite slightly decreased. Moreover, according to the shifts of PXRD, FTIR and P-31 ssNMR line positions, it was proved that zinc ions were successfully introduced into the crystal of DCPD. The (Ca + Zn)/P molar ratio calculated from ICP-OES results was ca. 1.0, which is typical for DCPD; only the (Ca + Zn)/P molar ratio of the sample with the highest concentration of Zn slightly differs, which was caused by the presence of alpha-hopeite. SEM images have shown a high tendency of Zn-containing brushite to agglomerate into the spherical, compact clusters. The preliminary biological tests have shown that the powders are non-toxic, which makes them promising materials for potential use in mineralised tissue engineering.

Automated summary

Dicalcium phosphate dihydrate (DCPD) enriched with different amounts of Zn2+ ions was synthesized in aqueous solution via standard precipitation method. Characterization tests confirmed the successful introduction of zinc ions into the DCPD crystal, making it a promising material for mineralized tissue engineering.