Doped biphasic calcium phosphate: synthesis and structure

Hydroxyapatite, tricalcium phosphate, and a mixture of these, i.e biphasic calcium phosphate (BCP), are widely employed as ceramic materials in hard tissue engineering, despite their poor mechanical and functional properties. The method of ionic substitution inside their lattice structures has been examined extensively by researchers in their long efforts to develop materials, that closely resemble natural hard tissues. The presence of dopants has a deep impact on the phase assemblage, structural, and functional behaviors of BCP. In this context, the goal of the current article is to cover different aspects of ongoing research on doped biphasic calcium phosphate. Apart from providing brief descriptions of different synthesis routes for producing ion-modified BCPs, the limitations of each technique are also discussed. In addition, particular emphasis has been given to describing the key experimental results, which elucidate the structural changes occurring due to doping. In particular, the preferable substitution sites of different dopant ions and the resulting crystallographic changes are depicted quite elaborately. Finally, the effects of substitution on biological and mechanical properties of BCP are briefly mentioned. In summary, the present review focuses on the ionic substitutions in BCP systems and their collective effects on material behaviors.