Preparation And Properties Of Degradable Strontium Hydroxyapatite/magnesium Oxychloride Bone Cement

Magnesium oxychloride cement（MOC）has the advantages of high strength,good adhesion and no cytotoxicity,and can be used as bone repair material.In this paper,MOC was compounded by nano hydroxyapatite（nHAp）,strontium hydroxyapatite（SrHAp）and xanthan gum（XG）to prepare biodegradable composite bone cement with good bioactivity and biocompatibility.（1）Firstly,nHAp was combined with MOC to study the effect of nHAp on the degradability and in vitro bioactivity of MOC.The results showed that MOC doped with 10 wt.%nHAp had the best physical and chemical properties.When soaked in simulated body fluid（SBF）for 28 d,the softening coefficient of 10 wt.%nHAp/MOC（0.39）was the highest among all samples,indicating that its water resistance was the best.The degradation rates of MOC during soaking process were lower than that of blank group,which effectively suppressed the defect of rapid degradation of MOC.The biocompatibility of nHAp/MOC and MOC was evaluated by implanting nHAp/MOC and MOC into rat muscle.The results showed that the incorporation of nHAp could enhance the biocompatibility of MOC.（2）Strontium hydroxyapatite（SrHAp）was combined with MOC to prepare a new bioactive material with good osteogenic activity and biodegradability.The results showed that after soaked in SBF for 28 d,the compressive strength loss rate of SrHAp/MOC was 53%,which was higher than that of MOC（93%）and nHAp/MOC（61%）,and the water resistance was the best.During soaking in SBF,SrHAp/MOC degraded and released Sr²⁺and the highest release concentration of Sr²⁺was 2.85 ppm.After SrHAp/MOC was implanted into the bone defect site of rats,the new bone tissue grew from outside to inside around the defect,indicating that SrHAp/MOC had good osteogenic activity.（3）SrHAp/MOC was modified by adding XG.The results showed that XG enhanced the anti-washout of SrHAp/MOC,and when XG≤1.5wt.%,the water resistance of SrHAp/MOC was improved.The results of animal experiments showed that SrHAp/MOC modified by 1.0 wt.%XG had good biocompatibility and promoted the growth of blood vessels and new bone.There are 26 figures,5 tables and 147 references.