Construction And Performance Of α-CPC Base-loaded Selenium Microsphere/GO Composite System

In clinical application,calcium phosphate cement（CPC）not only needs to have high mechanical strength,but also needs to have functional effects such as anti-cancer,anti-inflammatory,and osteocyte differentiation.The development of such functional materials has become the focus of current attention.It has been found that graphene oxide（GO）can promote cell differentiation,affect the structure of cement curing products,and enhance its mechanical properties.Selenium can inhibit the recurrence and migration of cancer cells.In view of the disadvantages of CPC,this study used CPC as the matrix,combined GO and Na₂Se O₃ microspheres to construct a selenium-loaded microsphere/GO/CPC composite system,in order to obtain calcium phosphate functional bone repair materials with enhanced mechanical strength and good physiological activity.The main contents of the thesis are as follows.（1）α-TCP matrix powder was prepared by high temperature solid phase method and co-precipitation method.The quality ofα-TCP was used as the performance index,and the material was characterized by XRD,DSC and SEM.Theα-TCP was calcined at 1450°C for 3 h by co-precipitation method.The best condition is under the condition of rapid cooling.The composition and solid-liquid ratio of CPC powder were optimized.The results showed that the performance of CPC was the best when the solid-liquid ratio was 2.4 g/m L and the composition of the solid phase wasα-TCP:Mg O:DCPA:HA=1:0.05:0.05:0.25.At this time,the initial setting time was 6 min,the final setting time was 7 min,the injectability coefficient was 0.93,and the compressive strength was 17.22 Mpa.（3）GO/CPC system was constructed with curing time,compressive strength and injectability as performance indexes,and the incorpora-tion percentage of GO was optimized.It was found that the compressive strength was22.49 Mpa when the GO doping amount was 0.2 wt%,the initial setting time was 5.5min,the final setting time was 10 min,and the injectability coefficient was 0.9.（4）Selenium-loaded microspheres were prepared by emulsion crosslinking method,and the experimental conditions were optimized by single factor and orthogonal experiments.The results showed that the optimal process conditions were as follows:the dosage was 0.05 g,the crosslinking time was 10 min,the crosslinking temperature was 40°C,and the dosage of crosslinking agent was 0.8 m L.Taking the drug loading as the performance index,the optimum process conditions were as follows,the dosage was 0.2 g,the crosslinking time was 50 min,the crosslinking temperature was 50°C,and the amount of crosslinking agent was 0.8 m L.The higher the encapsulation efficiency,the longer the drug stability and storage period,so the encapsulation efficiency was selected as the final performance index.Under these conditions,the encapsulation efficiency of the microspheres was 75.68%,the drug loading was 4.73%,and the cumulative release rate of selenium was 21.41%after 432 h of sustained release in vitro.（5）Taking the curing time as the performance index,the incorporation ratio of selenium-loaded microspheres in the GO/CPC system was optimized to construct a selenium-loaded microsphere/GO/CPC composite system.The results showed that when the doping amount of selenium-loaded microspheres was 2.5 wt%,the initial setting time was 6 min,the final setting time was 12.17 min,and the cumulative release rate of selenium was 18.26%after 432 h in vitro release.（6）The selenium-loaded microspheres/GO/CPC composite system had the highest inhibition rate of 86.03%and IC₅₀ of 322.977μg/m L on MG63 cells at 72 h and 1200μg/m L.The highest inhibition rate of Na₂Se O₃/GO/CPC composite system on MG63 cells was 94.77%at 72 h and1200μg/m L,and the IC₅₀ was 215.641μg/m L.The in vitro proliferation experiment of GO/CPC system on MG63 cells showed that GO/CPC promoted the proliferation of MG63 cells,and increased with the increase of concentration and action time.The selenium-loaded microsphere/GO/CPC composite system not only improves the mechanical properties of calcium phosphate bone cement,but also inhibits the proliferation and differentiation of osteosarcoma MG63 cells,which is beneficial to the postoperative anticancer effect.