Study On Preparation And Properties Of ?-tricalcium Phosphate Bioceramics Modified By Phosphate Glass

?-tricalcium phosphate??-TCP?bioceramic is an excellent bone repair material with good biocompatibility,safety and non-toxicity.It has been widely used in clinical treatment.However,?-TCP still has disadvantages such as poor sinteribility and lacking ability to regulate biological functions.In this study,strontium?Sr?or gallium?Ga?-containing phosphate glass was prepared as sintering additive for?-TCP,and the effects of the content,composition and sintering temperature of sintering additive on phase composition,phase stability,microstructure,mechanical properties,ion dissolution behavior and cell biological properties of?-TCP bioceramics and their honeycomb scaffolds were investigated.The strontium-containing phosphate glass?SPG-1;45P₂O₅-32SrO-23Na₂O?as a sintering additive for?-TCP was prepared by a melt-quenching method.The results showed that SPG-1 achieved liquid phase sintering for?-TCP at a sintering temperature of 1100°C,and SPG-1 reacted with?-TCP to form?-Ca₂P₂O₇;metal ions in SPG-1 patially replaced Ca²⁺in?-TCP,causing lattice distortion of?-TCP.When the amount of SPG-1 additive was15 wt.%,the ceramic had the highest compressive strength,and showed obvious effects of promoting osteogenic and inhibiting osteoclastic activity.When the amount of SPG-1additive was less than 15 wt.%,the mechanical properties of obtained ceramics could not be improved.However,when the addition of SPG-1 reached 20 wt.%,the ceramic sample produced obvious cytotoxicity due to the release of excess P⁵⁺,and the mechanical properties decreased due to the abnormal growth of the crystal grains.On the basis of SPG-1,the molar ratio of SrO and P₂O₅ in phosphate glass was gradually increased to prepare SPG-2 and SPG-3,respectively.The influence of component of glass sintering additive?20 wt.%?on the microstructure and properties of?-TCP ceramics were studied.Under the sintering temperature of 1100°C,SPG-2 and SPG-3 inhibited abnormal grain growth,so the compressive strength of TCP/SPG-2 and TCP/SPG-3 was increased by 1.4 times or more compared to that of pure?-TCP ceramic.The proliferation of mBMSCs on TCP/SPG-1 and TCP/SPG-3 was significantly inhibited due to the release of excess P ions.The TCP/SPG-2 showed significantly improved compressive strength,enhanced cell viability and osteogenesis,and inhibited osteoclast activity.Therefore,TCP/SPG-2 had the best overall comprehensive performance.The effect of SPG-1 on the phase stability and sintering properties of?-TCP was studied.At the sintering temperature of 1250°C,the SPG-1 sintering additive hindered the transformation of?-TCP to?-TCP.When the amount of SPG-1 additive was 10 wt.%,the phase transformation of?-TCP was completely inhibited.The addition of SPG-1 led to abnormal grain growth of the ceramic;this resulted in a decrease in the compressive strength of the ceramic compact,but did not reduce the mechanical properties of the porous ceramic.When the amount of SPG-1 was up to 10 wt.%,the compressive strength of obtained porous?-TCP ceramics was significantly improved.Honeycomb?-TCP bioceramic scaffolds were prepared by an extrusion method.The effects of gallium-containing phosphate glass?GPG?as sintering additive on the structure and properties of ceramic scaffolds were studied.At the sintering temperature of 1100°C,the addition of GPG made the strut of the honeycomb scaffolds denser,which significantly improved the compressive strength of the scaffolds.The ceramic scaffolds containing appropriate amount of gallium ions distinctly improved the cell proliferation.However,when the gallium content was too high,the scaffolds showed significant cytotoxicity.The GPG-modified scaffold significantly inhibited osteoclast-related gene expression and gene expression related to early-stage osteogenic differentiation,and the inhibition degree depended on the Ga³⁺concentration.The scaffolds with lower content of gallium ions enhanced gene expression associated with late-stage osteogenic differentiation.In summary,SPG and GPG sintering additives could stabilize the phase of?-TCP,promote the densification of ceramics,improve the mechanical strength,and regulate the cell response behaviors of?-TCP bioceramics and their scaffolds.By optimizing the parameters such as the content and composition of the sintering additive,the obtained?-TCP bioceramic can have good comprehensive properties and is suitable for repairing bone defects under the condition of excessive bone resorption.