Synthesis, characterization and in vitro evaluation of zinc and strontium binary doped hydroxyapatite for biomedical application

The aim of the present study is to examine the function of the two significant biological cations, Zn2+ and Sr2+, when co-doped in the structure of hydroxyapatite (HA). Six samples with different Zn2+ and Sr2+ concentrations were prepared by a hydrothermal process that includes the addition of Zn2+ and Sr2+ containing precursors to replace Ca2+ partially in the HA structure. The obtained nanomaterials were examined via XRD, ICP, FTIR, Raman spectroscopy, FESEM, TEM, and TGA for the investigation and confirmation of co-doping, crystallinity, phase purity, lattice parameters, elemental compositions, particle morphology, and thermal stability respectively. Interestingly the Zn2+ substitution increase with Sr2+ co-doping and the apatite structure going disappear up to 20% Zn10%Sr or 10%Zn20%Sr in the solution. Furthermore, in vitro cell viability even at high Zn2+ concentration (up to 6 wt %), MC3T3-E1 cells proliferated at a high rate on co-substituted HA materials, confirming that Sr2+ offset the cytotoxic effect of Zn2+ and increased the biocompatibility of the material. Moreover, the antibacterial effects of co-substituted HA against pathogen bacterial strains (E.coli and S.aureus) were also significantly increased. Overall results demonstrated that HA co-substituted by Zn2+ and Sr2+ at (10% Zn10%Sr-HA) is a potential material for hard tissue scaffolds.