Preparation And Properties Of Polyvinyl Alcohol/Calcium Phosphate Composite Bone Cement

Background For a long time,the problem of bone loss caused by accidental injury,disease and aging is a medical problem that medical workers urgently need to solve,although we can repair bone defects by implanting filling materials such as autografts,allografts,xenografts,etc.,the number of donor sources of these filling materials,in recent years,synthetic bone repair materials have been the research hotspot of scholars,calcium phosphate is the most important inorganic component in bone tissue,calcium phosphate cement(CPC)is considered as one of the most promising bone graft materials due to its superior Biocompatibility,bone conductivity,plasticity and injectability.However,the high brittleness of CPC limits its clinical potential,and Polyvinyl alcohol(PVA)fibers have been shown to improve the tensile toughness of concrete Polyvinyl alcohol in engineering cement,however,few researchers have applied PVA fiber in the field of medical biomaterials to improve the toughness of biomaterials.In this paper,CPC was modified by PVA fiber with high toughness,and the properties of CPC were evaluated.It was found that PVA fiber could greatly improve the mechanical properties of CPC,without affecting the Biocompatibility and bone conductivity of CPC itself.Objective To evaluate the cellular Biocompatibility of PVA CPC composites and to investigate the effect of PVA fibers with different mass fractions on the mechanical strength of CPC in vitro,to evaluate the extent to which the flexural strength,elastic modulus and fracture toughness of the composite are increased,and to evaluate the degradability,bone conductivity and bone inductivity of the composite,it provides a certain theoretical basis for the clinical application of the composite material.Method1.Preparation of PVA/CPC composite bone cement: PVA fiber was mixed with CPC solid phase at 1wt%,2.5 wt%,5wt%,and then mixed with solidified liquid at 1:2 to obtain PVA/CPC composite bone cement.2.The degradation of PVA/CPC composites was tested by immersion test in vitro.3.In vitro detection of the Biocompatibility of PVA/CPC composite bone cement: the Biocompatibility of the composite was evaluated by contact with the extract and direct contact culture,respectively,cell morphology and growth status were observed,CCK-8 reagent and Live/Dead fluorescence staining were used.4.In vitro determination of the osteogenic activity of PVA/CPC composite bone cement: an alkaline phosphatase assay kit was used to quantify the activity of ALP in the Alkaline phosphatase and in direct contact culture,qualitative staining of ALP was used.5.The flexural strength,flexural modulus,and fracture toughness of CPC were tested by a three-point bending test to evaluate the improvement of CPC mechanical properties by PVA.Results:1.PVA fiber can improve the mechanical properties of CPC bone cement to a great extent.Compared with the CPC control group,the bending strength of each experimental group increased at least 3 times,Young’s modulus decreased nearly 2times,and the defect of high brittleness of bone cement was improved The fracture toughness of the composites was increased by at least 120 times,especially the 5%PVA/CPC experimental group,whose fracture toughness was increased by nearly 250 times,and the fracture yield point of the composites was greatly delayed.2.The degradation rate of the PVA/CPC composite was not significantly different from that of the CPC control group.The degradation rate of the PVA/CPC composite was the highest in the first 10 days,and then gradually stabilized.3.There was no significant difference in cell morphology and growth between CPC control group and PVA/CPC Group,there was no significant difference in OD value and cell proliferation activity between CPC control group and experimental groups on Day 1,2 and 3 The results of Live/Dead fluorescence staining showed that the green cells(living cells)were the most in all groups and CPC control group,but the red cells(dead cells)were few.4.The results of the cell cross-section test showed that there was no significant difference in migration area between CPC control group and experimental groups at48 h,while the Transwell migration test showed that there was no significant difference in the number of cells migrating from upper chamber to lower chamber in each group,there was no significant difference in the density of cells under the microscope.5.The ALP quantitative test showed that there was no significant difference in ALP activity between CPC control group and experimental groups,and the ALP qualitative staining showed that there was no significant difference in staining depth among groups,which was consistent with the ALP quantitative results.Conclusion:The addition of PVA fiber can improve the fracture toughness of CPC bone cement to a great extent.In addition,it can improve the flexural strength and Young’s modulus,and make up for the defect of high brittleness of CPC bone cement,the composite material also retains CPC’s good Biocompatibility and bone conductivity.There was no significant difference between CPC bone cement and CPC bone cement in osteogenesis and degradation rate.