Preparation And Properties Of Mg²⁺/Ce³⁺ Co-doped Hydroxyapatite

With the development of medical technology,more and more green biomaterials have been used in clinical trials and produced many biomedical materials with good prospects.Hydroxyapatite（HAp）is one of the hottest materials currently studied,because of its ability to promote bone ingrowth,it is often used as a substitute for implants such as hip and knee joints,as well as a carrier for chemotherapeutics and antibiotic drugs.Magnesium（Mg）,as an essential trace element of organisms,promotes the growth of bone cells and plays a series of important roles in the mineralization and mechanical properties of bones.Cerium（Ce）is a rare earth element with anticavity potential.In this study,the ion-doped modified hydroxyapatite material was prepared by chemical precipitation method.The effects of magnesium ion and cerium ion doping on HAp structure and biological properties were studied.X-ray diffraction analysis（XRD）,Fourier transform infrared spectroscopy（FT-IR）,X-ray photoelectron spectroscopy（XPS）,transmission electron microscopy（TEM）,specific surface area（BET）and other analysis methods were used to characterize the modified HAp.Bovine serum Protein（BSA）adsorption test and bacteriostatic test were carried out to evaluate the adsorption performance and antibacterial property of modified HAp.The following conclusions were obtained:（1）The Ce-doped hydroxyapatite（Ce-HAp）materials with different Ce³⁺content were prepared by chemical precipitation method.The effect of Ce³⁺content on HAp structure was studied.The results showed that Ce³⁺can replace Ca²⁺in HAp when the Ce³⁺content was in the range of 0-10 mol%.With the increase of Ce content,the grain size and crystallinity of the samples decreased and agglomeration was easily to occur.Ce³⁺doping didn’t affect the basic pore structure of hydroxyapatite.（2）Magnesium cerium co-doped hydroxyapatite（Mg/Ce-HAp）material were prepared by chemical precipitation method.Different doses of Ce³⁺were doped under a certain condition of Mg²⁺.The effect of Mg²⁺to the structure of Ce-doped HAp was studied.The results showed that the intensity of the main diffraction peak was gradually weakened and the peak width was increased.Mg²⁺can be partially incorporated into the HAp lattice,which reduced the sample size and increased the specific surface area of the material.The effect of calcination temperature on the structure of Mg/Ce-HAp material was studied.It was showed that the crystallinity of the sample increased with the increase of calcination temperature.When the calcination temperature reached 800°C,the grains broke down and bonded.（3）The adsorption performance of Ce-HAp and Mg/Ce-HAp materials under different pH conditions and the effect of calcination temperature on adsorption under different pH conditions were studied by biological experiments.The results showed that the adsorption capacity of Ce-HAp increased with the increase of the amount of Ce³⁺when Ce³⁺content was in range of 0-10 mol%.Under the condition of a certain amount of Mg,the adsorption capacity increased first and then decreased with the increase of Ce³⁺doping,when the content of cerium was 8 mol%,the adsorption capacity reached the best.The adsorption amount of the same material in the solution with pH 4.5 was higher than that in the solution with pH 6.7;With the increase of calcination temperature,the adsorption amount of Mg/Ce-HAp materials increased first and then decreased,and the adsorption capacity reached the best after calcinated at 500°C.The results of bacteriostasis test showed that antibacterial property increased with the increase of Ce³⁺content.When the Ce³⁺content was 10 mol%,the antibacterial rate reached 96.53%.The doping of Mg²⁺could promote the antibacterial activity of Ce^3+/4+.After calcination at 600°C,the antibacterial property reached the best,and the antibacterial rate is 99.93%.