High throughput synthesis and screening of zinc-doped biphasic calcium phosphate for bone regeneration

Abstract

Introducing high throughput experimental/screening method into the elements-doped calcium phosphate is expected to greatly increase the efficiency of finding out the most effective doping range. In this work, biphasic calcium phosphate (BCP) was used as the doping matrix and zinc was chosen as the doping element. The zinc-doped BCP with gradient doping content (0–10.0 mol.%) were synthesized by a high throughput chemical precipitation method. The effects of doping content on the phase, structure, morphology and cytological responses of zinc-doped BCP were investigated comparatively. The results showed that BCPs with similar composition while different zinc doping content were successfully prepared, and zinc tended to enter the β-TCP structure by substituting calcium at the Ca(5) and Ca(4) sites. The zinc concentration in powder extracts rose steadily with increasing the doping content of zinc. However, a burst release of zinc in the BCPs into the extracts appeared when the zinc doping content was higher than 6 mol.% and resulted in cell apoptosis. Zinc doping could effectively promote the osteogenic differentiation of bone marrow mesenchymal stem cells and regulated the expression of inflammatory and tissue healing related genes in macrophages for proper doping contents. The in vitro most effective zinc doping content range and doping content was 2.0–2.8 mol.% and 2.4 mol.%, respectively. Furthermore, the most effective zinc doping content was verified by the in vivo osteoinduction experiment conducted in beagle dorsal muscle. This work provides a reference for figuring out the effective doping content range of element in calcium phosphate and paves the way for developing a more bioactive BCP material for bone tissue engineering.