Fabrication And Properties Of Magnesium Phosphate Bone Cement Composite Scaffolds With Directional Pores

Every year,the number of patients with fracture and bone defect caused by traffic accident,bone tumor,osteoporosis and so on is increasing day by day.Implanting artificial bone replacement material has become one of the effective methods to treat bone defect clinically.Magnesium phosphate bone cement(MPC)has been widely studied because of its advantages of high early strength,good adhesion,short setting time and biodegradability.However,due to the characteristics of self-curing of bone cement,it is difficult to produce pores in the course of reaction,which is not conducive to the transport of nutrients and can not provide a channel for osteoblast growth,resulting in limited bone repair ability.To solve this problem,the MPC bone cement support was prepared by in situ hydration reaction,study the influence of slurry solid content,reaction concentration and reaction time on the structure,mechanical properties and biological properties of the hole,and analyze the pore morphology,compression strength and biological compatibility of porous MPC/CS bone cement composite scaffolds.MgO porous scaffolds with controllable porosity and lamellar spacing through the freeze-drying process,MPC scaffolds were obtained after hydration in KH₂PO₄ solution.As the concentration of KH₂PO₄ solution increases and the reaction time increases,the compressive strength increases finally.When the solution concentration of KH₂PO₄ and the reaction time are 0.15 g/mL and 60 min,the porosity and compressive strength of MPC cement scaffold are 50.86%and 9.03 MPa respectively.Biological experiments in vitro showed that MPC bone cement scaffolds formed flower clusters or lump deposits on the surface,can promote bone integration,shorten the time of recuring.But the MPC degradation rate is fast,causes the surrounding environment pH value to be too high,its biocompatibility needs to be further improved.The hole surface of the bone cement support is covered by CS after applying the inner wall of the MPC porous bracket to 2.5 wt.%CS in the-0.1 MPa vacuum drying box by impregnation.During compression,the crack initiation probability on the hole wall is reduced,and the crack deflection occurs between polymer and ceramic hole wall.The compressive strength increased from 9.03 MPa to 19.98 MPa Moreover,because the CS coating reduces the degradation rate of the MPC scaffold and its own degradation products are acidic,the pH value of the surrounding environment of the scaffold is close to that of the human body.The in vitro biological experiments showed that cluster mineralization products appeared on the surface and pore of MPC/CS cement composite scaffold,and almost completely covered the pores with the prolongation of mineralization time,and the proliferation of osteoblasts increased obviously.It shows that MPC/CS cement composite scaffold has good mineralization and biocompatibility.