| Trauma fractures,bone tissue necrosis,bone tumors,bone tuberculosis and other diseases that cause bone defects are still clinically difficult.Bone transplantation is generally used to treat the disease.However,the widely used natural bone repair materials have problems such as insufficient sources,complications and immune rejection,and their applications are greatly limited.It is urgent to develop artificial bone repair materials to solve the above problems.The currently developed bone repair materials have been proven to have good bone graft healing effects,but there are still a small number of patients with bone graft non-union and other problems,mainly due to their certain differences from natural bone structure and composition,resulting in insufficient bone promoting activity.In response to the above problems,this paper proposes to functionally compound the zinc element(Zn)and nano-hydroxyapatite(HA)that promote osteogenic induction to prepare a bone-imitation structural activity-enhancing hydroxyapatite bone repair material and improve the existing materials.Insufficient activity and other problems,improve its bone repair ability.Based on this,based on the analysis of the structure and active elements of natural bone repair materials,porous Zn O/HA biocomposites were prepared using spark plasma sintering(SPS)technology without binder.The effects and mechanisms of different sintering temperatures,the amount of pore-forming agent and the content of Zn O on the microstructure,pore characteristics,mechanical properties,in-vitro mineralization and degradation behavior of composite materials were studied.The following conclusions are obtained:Porous Zn O/HA composites with 25 wt.% pore-forming agent and 6.2wt.% Zn O content were prepared at different sintering temperatures.The results show that the composite material is composed of HA and Zn O phases at a sintering t emperature of 950°C.When the sintering temperature exceeds 950°C,a small amount of the TCP phase of HA decomposition products appears,indicating that excessively high sintering temperature will cause HA to decompose;As the sintering temperature increases,the pore size in the composite becomes smaller,the through-hole structure between the large and small pores disappears,its compressive strength decreases slightly,and the elastic modulus does not change much.At a sintering temperature of 950°C,por ous 6.2wt.% Zn O/HA composites with pore-forming agents added at 25,50 and 75 wt.% were prepared.The results show that with the increase of the amount of pore-forming agent,the porosity of the composite material is 42.04%,51.26% and 62.70%,respectively,the porosity is significantly improved,the pore size becomes larger,and the through-hole structure between the large and small pores becomes more;As the amount of pore-forming agent added increases,the compressive strength decreases from 148 MPa to 56 M Pa,and the elastic modulus decreases from 6.5GPa to 3.5GPa.Although high porosity is conducive to cell adhesion,growth and crawling,it will cause deterioration of its mechanical properties.At a sintering temperature of 950°C and a pore-forming agent content of 25 wt.%,porous composite materials with Zn O contents of 0,1.3,3.7,6.2 and 8.7 wt.% were prepared.The results show that as the content of Zn O increases,the porosity of the composite material does not change much,about 40%,the pores are eve nly distributed on the surface of the material,the pore size is between 50 and 400 ?m,and there is a through-hole structure between the large and small pores.The compressive strength decreased slightly.Between 157 and 148 MPa,the elastic modulus did no t change much,around 6.5GPa.The in-vitro mineralization behavior shows that as the porosity changes from 42.04% to 62.70%,more and more bone-like apatite is deposited on the surface of the composite after 7 days.Compared with low porosity,the matrix o n the surface of the material under high porosity is already very large.It is difficult to observe that as the Zn O content increases from 0wt.% to 8.7wt.%,more and more bone-like apatite is deposited on the surface of the composite material after 7d.Com pared with the 0wt.% content,the material at 8.7wt.% content The surface matrix has not been observed.The degradation behavior showed that as the porosity increased,the degradation rate of the composite material accelerated.After 70 days,the degradati on rate of the composite material at low porosity was about 1.0%,while the degradation rate of the composite material at high porosity could reach about 1.5%.With the increase of Zn O content,the degradation rate of the composite material becomes faster.After 70 days,the degradation rate of the composite material with 8.7wt.% Zn O content is about 1.6%,while the degradation rate of the composite material without Zn O is only about 0.8%.In summary,the porous Zn O/HA composite material prepared by SPS has a porosity,pore size and structure similar to that of natural bone repair materials.Compared with the existing hydroxyapatite-based artificial bone repair materials,it also has Similar pore characteristics.Since the addition of Zn element will improve the material's ability to promote bone formation,as the material degrades,Zn2+ can also be released,continuously stimulating osteoblasts,no binder is added during the preparation process,effectively avoiding the cause of the binder Cytotoxicity,as a bone repair material,has potential application prospects in clinic. |
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