3D Printing Advanced Porous Bioceramic Scaffolds

With the rapid development of society and gradual deterioration of ageing of population in our country,the number of the caces of bone trauma caused by various causes is increasing,which leads to an urgent need and a great challenge in clinical applications of artificial biomaterials for bone defect repair.In general,biomaterials for bone repair require three-dimensional porous structure,degradability and high mechanical strength,as well as microporous network and high porosity that are conducive to the inward growth of osteoblast related cells,which is also the focus of research in this field for a long time.However,there are still some problems in the regulation and control of the microstructure,mechanical properties and biodegradability of porous scaffolds,which mainly involve the poor comprehensive performance of existing biomaterials,and the difficulty of conventional processing and manufacturing technology in solving the problems of multiple factors such as the collaborative optimization of the pore structure of materials and its mechanics,activity and degradation.In this article,the self-designed 3D-printing technology platform of coaxial double nozzle grouting was used to print and construct the core-shell bioactive ceramic scaffolds with wollastonite(CSi)and zinc or strontium doped diopside(Dio,ZnDio,SrDio)(such as CSi@Dio,CSi@ZnDio,CSi@SrDio).The results showed that the two components of this series of calcium silicate scaffolds were distributed in the core-shell structure within their skeletons,which was extremely beneficial to reconcile the problems of too fast or slow degradation of CSi and Dio,respectively,and the incorporation of Zn or Sr ions into the shell Dio could further adjust the initial mechanical strength and early degradation rate of the scaffolds.According to this,in this article,the organic microspheres were added into the Dio ceramic powder slurry in advance,the internal microstructure of the porous scaffold framework 3D-printed and constructed was further adjusted,and then the Dio shell component was endowed with high-density spherical microporous structure,so as to further to achieve the excellent effect of precise tailoring for the degradation rate and ion release of the shell and core components in the early stage.Second,according to the limitations of conventional techonology of DIW on the control of pore shape and material shape and structure,this paper further used the techonology in additive manufacturing of stereolithography based on the digital light process,and carried out a study of tailoring the internal microstructure of skeleton in the scaffolds fabricated with the stoichiometric ratio of wollastonite(such as CSiMg10Sr5-p0,CSi-Mg10Sr5-p8,CSi-Mg10Sr5-p16,CSi-Mg10Sr5-p24).It was found that adding polystyrene microsphere pore forming agent to Mg and Sr doped wollastonite/resin slurry could realize the tailoring of microporous structure in porous scaffolds.For the first time,the study realized the modulation of multi bioactive ions release such as calcium,silicon,magnesium,strontium and the mechanical decay of scaffolds,which developed a new technical scheme for adjusting the mechanical properties and biodegradation synchronously of 3D-printed by stereolithography.Thirdly,this article also constructed a variety of bioceramic scaffolds with controllable pore morphology(such as Gyroid,Cylindrical,Cubic)and pore surface modification by 3D-printing stereolithography,and used the scaffolds with surface modification to repair and reconstruct the critical scale defects of femur in osteoporotic living animals.The preliminary experimental results showed that the biomimetic modification of the pore surface in different degrees had a significant impact on the early repair of pathological bone defects.In this study,the biomimetic apatite coating containing a variety of trace elements can effectively promote the regeneration and repair of osteoporotic bone defects.These results provide more reliable artificial biomaterials to resolve the problem of clinical pathological bone damages in future.