Synthesis Of Elements Doped Hydroxyapatite And Performance Of Modified Bone Cement

Strontium(Sr)doped hydroxyapatite(HA)has been widely used in biological field.In this work,HA,Sr doped and Mg doped HA nanoparticles were synthesized by hydrothermal method.A series of experiments and the density functional theory(DFT)were used to investigate the effect of Sr,Mg doping on the chemical composition,crystallinity,lattice parameters,morphology and formation energy of HA.The experimental results indicated that after Sr doping,the lattice parameters and crystal size of nanoparticles increased.While after Mg doping,the lattice parameters and crystal size of nanoparticles decreased.And along with the increasing amount of Sr doped,the crystallinity of HA nanoparticles did not change significantly.While along with increasing amount of Sr doped,the crystallinity of HA nanoparticles decreased significantly.The lattice parameters obtained from the simulation method confirmed the experimental results.And the simulation results indicated that the formation energies of Sr doping HA nanoparticles were lower,which meant that the structure of Sr doping nanoparticles were more stable.It illustrated that when the concentration of Sr doped is 10%,the Ca(1)site was the preferential site for Sr;while when the concentration of Sr doped is 50%,mixed doping was a more preferred doping mode.The results also showed when the concentration of Mg doped was 10%,the Ca(2)site was the preferential site for Mg;and when the concentration of Mg doped was 20%,the mixed doping was a more preferred doping mode.Calcium sulfate bone cement was an emerging bone replacement material with many advantages,such as plasticity,self-curing,bone induction and excellent biological activity.In this article,the composite calcium sulfate cement was synthesized by adding the HA and doped HA into the solid phase of the cement.The compressive strength,degradation rate,p H and morphology of the cement were analyzed.The results showed that during the degradation process of calcium sulfate composite bone cement,calcium phosphate salts were produced.The addition of HA and Sr doped HA increased the void ratio between calcium sulfate dihydrate in composite bone cement and reduced the compressive strength.At the same time,the addition of HA and Sr doped HA also accelerated the degradation of calcium sulfate bone cement.In conclusion,this paper provides a new way to study the change of HA lattice through the combination of experimental and computer simulation methods.And the modified HA could be added into the calcium sulfate bone cement to improve its performance,thus improving the feasibility of calcium sulfate bone cement in practical clinical application.