Synthesis and Characterization of Neodymium(III) and Gadolinium(III)‐Substituted Hydroxyapatite as Biomaterials

Nanocrystalline hydroxyapatite (HA), Ca 10 (PO 4 ) 6 (OH) 2 , substituted with gadolinium(III) (Gd 3+ ) and neodymium(III) (Nd 3+ ) in different mole ratios (M added /Ca added = X M , 0.01, 0.05, 0.1, and 0.2), was synthesized by an ion‐exchange method. All samples had the single phase of HA except for X M =0.2, which displayed the second phase of M(OH) 3 . All were B‐type carbonated HA. The nanoparticles were elongated spheroids of around 70 nm, and the shape and size did not change significantly with an increase of X M . The M(III)‐doped HA had higher electrical conductivity compared with pure HA. A cytotoxicity test showed all were noncytotoxic except for X Gd =0.2.