Preparation And Properties Of Modified Hydroxyapatite Ceramics With Better Bioactivity Via Infiltrating And Cladding

Hydroxyapatite?HA?is well-known as one of excellent bone repair biomaterials because of its chemical similarity with biological apatite.However,low biodegradation and weak bioactivity obstruct its application.It has been proved that the bioactive and biodegradation of HA ceramic could be enhanced by the introduction of zinc-containing or silicon-containing substances.In this paper,zinc or silicon with osteogenesis and/or angiogenesis property was introduced into HA ceramic via infiltration or cladding method.The existential form of elements and the effect of elements on the physical,chemical and biological properties of HA ceramics were studied.The biodegradation and bioactive of HA ceramics could be improved by infiltration or cladding method,which can help expand the clinical application of HA ceramics.Zinc has outstanding osteogenesis,to enhance the bioactive of HA ceramics,modified ceramics were prepared by infiltrating in the solution of Zn?NO₃?₂.After sintering,zinc was uniformly distributed in HA ceramics in the form of agglomerate ZnO grains.The porosity and in vitro mineralization ability of modified HA ceramics was elevated,and the density and compressive strength were reduced.Moreover,mouse bone mesenchymal stem cells?mBMSCs?cultured on modified bioceramic displayed better adhesion morphology and proliferation.But higher concentration of Zn?NO₃?₂ solution??0.75 mol/L?obstructed the proliferation and alkaline phosphatase activity of mBMSCs.Silicon has excellent osteogenesis and angiogenesis,so silicate-based BG sol was used to infiltrate HA per-sintered bodies to prepare modified HA ceramics.The modified HA bioceramic exhibited an interesting phenomenon that the HA grains were uniformly enveloped by the small silicate-containing grains on boundaries.The porosity of modified HA ceramics was elevated,and the density was reduced.The compressive strength of the modified HA bioceramic was much higher than that of the HA bioceramic modified by BG via mechanical blending method,in spite of slightly lower than that of the blank.The faster degradation of SiHA bioceramics might be attributed to the higher solubility of Ca₅?PO₄?₂Si O₄ and CaSi O₃.Meanwhile,submicron pores in SiHA bioceramic offered bigger surface area to contact with the solution,so the dissolution of bioceramics was accelerated.Silicate-containing grain boundary phases improved the cell adhesion,spreading,proliferation,osteogenic differentiation and angiogenesis ability.HUVECs and mBMSCs on modified ceramics exhibited preferable cell-biological performances than those on HA-0,implying that silicate-containing grain boundary phases endowed HA bioceramic better osteogenesis and angiogenesis.To farther study the effect of silicon to enhance the osteogenesis of HA ceramics,HA powder was uniformly embraced by BG gel to get modified HA ceramics.Ca₅?PO₄?₂Si O₄ was produced by the reaction between BG gel and HA.After modified by cladding method,the porosity of modified HA ceramics was elevated,and the density and compressive strength were reduced.More platy crystals were detected in modified HA ceramics after immersed in simulated body fluid for 7 d.Moreover,mBMSCs cultured on modified HA bioceramics displayed better adhesion morphology,more preferable proliferation and higher expression of osteogenesis-related gene.The osteogenesis of HA ceramic was enchanced by cladding method.