Study On Bioactivity And Antibacterial Activity Of Absorbable Bone Cement

Bone defect is one of the common diseases in clinic.The research of bone repair materials has important medical and economic value.As a traditional bone repair material,calcium sulfate cement has good biocompatibility,injectability,degradability,and osteoconductivity.However,the clinical application of calcium sulfate cement is hindered due to its short injection time,fast degradation rate,and poor early bone conductivity.In addition,bone filling operation has the risk of infection,therefore,the research of bone cement with antibacterial activity has very important clinical significance.In this work,O-carboxymethyl chitosan was added to the liquid phase of calcium sulfate cement,then the effect of its concentration on the injection,degradation behavior,osteogenic activity,and compressive strength of calcium sulfate cement was explored.Moreover,in order to improve its antibacterial properties,silver/strontium doping hydroxyapatite was added to the solid phase of calcium sulfate bone cement,then the release behavior of silver and its influence on the compressive strength and microstructure of bone cement were explored.The injection,compressive strength,release behavior,morphology and composition of the material were characterized by injection test,universal testing machine,ICP-OES,SEM,and XRD,respectively.The results showed that the injection time of O-carboxymethyl chitosan/calcium sulfate cement was increased with increasing the concentration of O-carboxymethyl chitosan and was more than 5 min for each sample.The compressive strength value of the improved bone cement which was higher than that of calcium sulfate cement was in the range of 11 18 MPa and it was increased with the increasing O-carboxymethyl chitosan concentration until the O-carboxymethyl chitosan content was up to a threshold of 0.5 wt.%?17.7±1.6 MPa?.The degradation rate of O-carboxymethyl chitosan/calcium sulfate cement was decreased with increasing the O-carboxymethyl chitosan concentration.The pH value was in the range of 7.2 7.4 and Ca²⁺ concentration was within 6 8 m M.The in vitro mineralization experiment showed that the induced mineralization ability of O-carboxymethyl chitosan/calcium sulfate cement was higher than that of pure calcium sulfate cement.MTT test indicated that the O-carboxymethyl chitosan/calcium sulfate cement was non-cytotoxicity.The antibacterial experiment showed that the silver/strontium doping hydroxyapatite/calcium sulfate cement had good antibacterial properties to both Escherichia coli and Staphylococcus aureus.The ICP-OES test showed that Ag ions had sustained release behavior which indicated that the silver/strontium doping hydroxyapatite/calcium sulfate cement had sustaining antibacterial properties.The XRD,SEM,and compressive strength test showed that silver/strontium doping hydroxyapatite/calcium sulfate cement was composed of silver/strontium doping hydroxyapatite and calcium sulfate dehydrate phases,and its compressive strength was fairy with cancellous bone.In summary,the injectability,compressive strength,and osteogenic activity of calcium sulfate cement can be improved by the addition of O-carboxymethyl chitosan which has good biocompatibility.Silver/strontium doping hydroxyapatite can be used as an antibacterial additive of calcium sulfate cement.The results of this study showed that the bioactive and antibacterial absorbable bone cement has great potential in orthopedic application for bone repair.