Development And Performance Studies Of Customized Porous Magnesium-doped Bioceramic Implant For Orbital Reconstruction

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Development and performance studies of magnesium-doped bioceramic for orbital reconstructionPurposeOrbital implant plays a critical role in orbital reconstruction.The ideal orbital implant should meet the prerequisites of considerable mechanical strength,good biocompatibility and bioactivity,and appropriate biodegradation which matches new born formation.In this study,we aimed to develop the magnesium(Mg)-dilute doping CSi ceramics with varied Mg/Ca molar ratio for orbital reconstruction,and study their properties as well as optimal fabrication condition.MethodsThe Mg-doped CSi with different Mg/Ca ratio,x(x =0,3,6,10%),were synthesized through a chemical precipitation method and a pressureless sintering process.The crystalline phase and microstructure of the sintered bioceramics were identified by X-ray diffractometer(XRD)and scanning electron microscopy(SEM),respectively.The compressive strength(Cs),elastic modulus(Em),flexural strength(Fs),Young's modulus(Ey)and fracture toughness(KIC)were measured by a universal testing machine.The in vitro biodegradation of the specimens was measured by soaking the ceramic samples in Tris-HCl buffer.For evaluation of in vitro bioactivity,the bioceramic specimens were immersed in simulated Body Fluid(SBF).ResultsIn this study,dilute Mg-doped bioceramics were successfully established by chemical precipitation following with pressureless sintering process.With a simple pressureless sintering process,the CSi-Mg6 and CSi-Mg10 ceramics exhibited significant enhancement in mechanical strength and fracture toughness,showed depressed degradation rate,and maintained good bioactivity.ConclusionsIn summary,we have found that a new strategy of Mg dilute doping is an effective way to improve the several important mechanical parameters and to tune the biodegradation rate in vitro of P-CSi ceramic.In this regard,the ?-CSi with appropriate Mg dilute doping ceramic is promising for orbital reconstruction applications.Part ? Development and performance studies of 3D Printed porous magnesium-doped bioceramic scaffolds for orbital reconstructionPurposeSince dilute Mg-doped bioceramic were successfully fabricated with chemical precipitation and pressureless sintering,we aimed to establish a 3D printed porous scaffold based on direct ink writing(DIW)method with bioceramic ink,as well as to demonstrate the feasibility of this approach in customized manufacture.MethodThe Mg-doped CSi powder with different Mg/Ca ratio were synthesized through a chemical precipitation method.The "ink" paste was prepared by mixing the ball-milled ceramic powder with polyvinyl alcohol(PVA)solution.The bioceramic scaffolds was printed layer by layer by a direct ink writing printer with different printing parameters.The strut width,pore size and porosity of the 3D printed bioceramic scaffolds as well as their influence on mechanical properties were systematically studied.The effect of the sintering temperature and heating schedule on the compressive strength of the porous scaffolds was also examined.ResultsBeyond the traditional phase conversion or biphase mixing hybrid,we developed the dilute magnesium-doped wollastonite inks and three-dimensional(3D)printing approach to fabricate bioceramic porous scaffolds.Using this unique Mg-doped ?-CSi and one-or two-step sintering approaches,the new bioceramic scaffolds exhibited ultrahigh compressive strength(>120 MPa)that is an order of magnitude higher than the pure CSi and other Ca-Mg silicate porous bioceramic.We also found that sintering temperature and heating schedule is an efficient approach to control the grain growth and enhance mechanical strength of the dilute Mg-doped CSi scaffolds.ConclusionCustomized Mg-doped porous bioceramic scaffolds with adequate open porosity were successfully built by direct ink writing method.The pore size,porosity and microstructure could be regulated by adjusting printing parameters.The new bioceramic scaffolds exhitbited ultrahigh mechanical strength,which opens the door for the 3D printing bioceramic manufacture and patient specific orbital reconstruction applications.Part ? In vitro study of customized porous magnesium-doped bioceramic scaffolds for orbital reconstruction on biological performancePurposeIn this part,we aimed to systematically evaluate the biological performace of the porous customized porous magnesium-doped bioceramic scaffolds in vitro,which would benefit further in vivo and clinic studies.MethodIn vitro study was carried out to evaluate the biological performance of the porous bioceramic scaffolds.Mouse bone marrow derived stem cells(mBMSCs)were cultured on TCP,CSi and CSi-Mg10 scaffolds.Cell attachment and viability were tested by PrestoBlue assay to evaluate the cytocompatibility of the scaffolds.Cell morphology and distribution were observed by laser scanning confocal microscope and scanning electron microscope.Osteogenic differentiation-related maker genes were detected by Real-time polymerase chain reaction,and mineralization was quantified as well.ResultsAll groups of scaffolds were suitable for mBMSCs attachment and proliferation.The overall cell viability of the 2 groups was higher than that of the control.During the same culturing period,cells in CSi and CSi-Mg10 groups showed more lopodia than that on TCP scaffolds.CSi group showed highest expression of osteogenic genes among the three groups.The CSi and CSi-Mg10 group both showed higher mineralization than the control.However,the mineralization delayed in CSi-Mg10 group at the initial stage which accelerated later due to degradation.ConclusionThis research presents that 3D printed porous diluted magnesium-doped scaffolds have the superiority of both biocompatibility and osteogenic activity in vitro.In this regard,the mechanically strong 3D printed porous bioceramic scaffolds with appropriate dilute Mg doping is promising for orbital reconstruction applications,and further in vivo and clinical studies are needed.