Construction Of Magnesium Phosphate-based Bone Cement Repair Material System

Bone cement has a certain position in the field of bone repair,among which calcium phosphate bone cement（CPC）has been widely studied due to advantages of self-curing,plasticity,good biocompatibility and good bone induction in vivo.However,the lack of mechanical properties,poor dispersion of slurry,insufficient stability,long curing time and other shortcomings hinder the development.In recent years,scholars have turned to explore the application of magnesium phosphate bone cement（MPBC）in clinical bone repair.In the study of magnesium phosphate bone cement（MPC）,the compressive strength,morphology and other properties of magnesium phosphate bone cement after curing are mostly discussed,while there are few reports on the requirement of magnesium phosphate bone cement minimally invasive medicine bone repair resist the collapsibility and injectability.Therefore,this paper construct magnesium phosphate based bone cement which has a certain compressive strength good antibreak performance and injectable performance.By preparing folic acid coupled chitosan loaded adriamycin hydrochloride nanoparticles（DOX-FA-CS）,and then constructing the drug loading bone cement system with magnesium phosphate based bone cement,the drug loading magnesium phosphate based bone cement bone repair material system was obtained.In this paper,magnesium phosphate（Mg O）,potassium dihydrogen phosphate（KH₂PO₄）,calcium dihydrogen phosphate（Ca H₂PO₄）were used as solid powder,citric acid and sodium alginate as liquid phase to prepare magnesium phosphate bone cement.By changing the content of magnesium oxide,citric acid and sodium alginate,the effects of the degradation p H compressive strength,injectability,antifragmentation and cytotoxicity of bone cement were studied.The results showed that:with the increase of magnesium oxide content,the extractionsolution p H increased,and it was injectable.The addition of citric acid can help delay the curing process of MPBC system,not only can the curing time be controlled within the golden time of clinical surgery（15～25 min）,improve the injectability,correspondingly enhance the compressive strength of bone cement,and reduce the p H of the system,with basically no effect on cell proliferation.The experimental results show that the compressive strength can reach 37 Mpa.The addition of sodium alginate can significantly improve the injectability and anti-break property of the slurry,and the injectability can reach 90%and the antibreak property can reach more than 93%.Determined by MTT experiment results show that the cell toxicity areⅠlevel（>0.8）,good biocompatibility.Folate-conjugated chitosan nanoparticles（FA-CS）were prepared by chemical reaction,and folate-conjugated chitosan-loaded doxorubicin hydrochloride nanoparticles were prepared by ion crosslinking.The formation mechanism of folic acid active ester and the coupling mechanism of folate-chitosan were studied,and the active ester of folate was purified to lay a foundation for the preparation of drug-loaded bone cement.Folic acid（FA）standard curve was drawn and folic acid coupling ratio and folic acid coupling amount of folic acid in folate-conjugated chitosan nanoparticles were determined.The standard curve of doxorubicin was drawn,and the encapsulation rate and drug loading rate of drug-loaded nanoparticles were determined by infrared spectrometer folic conjugated chitosan nanoparticles and drugloaded folic acid conjugated chitosan nanoparticles.The results showed that folic acid had successfully conjugated chitosan（CS）.Finally the release system adriamycin hydrochloride nanoparticles loaded with MPBC folic acid coupled with chitosan constructed.The antitumor properties of DOX-FA-CS bone cement with different fraction dilute extract concentration on osteosarcoma cells were analyzed.Results show that different qualityfraction DOX-FA-CS bone cement leaching solution and concentrations extract on osteosarcoma cell tumor resistance is good,5%,10%,15%,mass fractio of DOX-FA-CS bone cement as drug loadings,the inhibitory rate increased,with the loss of the leaching solution concentration inhibitory rate reduceobviously inhibitory rate range between 15%～50%,the drug loadings was 15%,have the largest anti-tumor rate,maximum anti-tumor rate was 50%.