Novel in-situ synthesis and characterization of nanostructured magnesium substituted β-tricalcium phosphate (β-TCMP)

Tricalcium phosphate (TCP, Ca3(PO4)2) in its pure form cannot be synthesized under physiological conditions in normal aqueous solutions due to phase instability, resulting in its transformation to hydroxyapatite (HA, Ca10(PO4)6(OH)2) in the presence of water. However, substituting magnesium in lieu of calcium is known to stabilize TCP, preventing its conversion to hydroxyapatite. There are several methods known for synthesizing magnesium substituted tricalcium phosphate (TCMP). In the present study, a novel in-situ method has been developed to synthesize β-TCMP using magnesium substituted brushite as a precursor.Substitution of 50% of calcium by magnesium results in the formation of semi-spherical nanocrystalline particles (∼ 100 nm) of brushite. Boiling the nanocrystalline brushite powder in aqueous condition for only 30 min results in the generation of rosette shaped nanocrystals (∼ 80 nm) of β-TCMP that emerge from the original brushite spheres. The β-TCMP particles exhibit a specific surface area of ∼ 200 m2/g. Details about the synthesis procedure and the possible mechanisms involved in the formation of β-TCMP from Mg-substituted brushite is further discussed.