Tuning zinc content in wollastonite bioceramic endowing outstanding angiogenic and antibacterial functions beneficial for orbital reconstruction

Prosthetic eye is indispensable as filler after enucleation in patients with anophthalmia,whereas there are still many complications including postoperative infection and eye socket depression or extrusion during the conventional artificial eye material applications.Some Ca-silicate biomaterials showed superior bioactivity but their biological stability in vivo limit the biomedical application as long-term or permanent implants.Herein we aimed to understand the physicochemical and potential biological responses of zinc doping in wollastonite bioceramic used for orbital implants.The wollastonite powders with different zinc dopant contents(CSi-Znx)could be fabricated as porous implants with strut or curve surface pore geometries(cubic,IWP)via ceramic stereolithography.The experimental results indicated that,by increasing zinc-substituting-Ca ratio(up to 9%),the sintering and mechanical properties could be significantly enhanced,and meanwhile the bio-dissolution in vitro and biodegradability in vivo were thoroughly inhibited.In particular,an appreciable angiogenic activity and expected antibacterial efficacy(over 90%)were synergistically achieved at 9 mol%Zn dopant.In the back-embedding and enucleation and implantation model experiments in rabbits,the superior continuous angiogenesis was corroborated from the 2D/3D fibrovascular reconstruction in the IWP-pore CSi-Zn9 and CSi-Zn13.5 groups within very short time stages.Totally,the present silicate-based bioceramic via selective Zn doping could produce outstanding structural stability and bifunctional biological responses which is especially valuable for developing the next-generation implants with vascular insertion and fixation in orbital reconstruction prothesis.

Next-generation finely controlled graded porous antibacterial bioceramics for high-efficiency vascularization in orbital reconstruction

Eyeball loss due to severe ocular trauma,intraocular malignancy or infection often requires surgical treatment called orbital implant reconstruction to rehabilitate the orbital volume and restore the aesthetic appearance.However,it remains a challenge to minimize the postoperative exposure and infection complications due to the inert nature of conventional orbital implants.Herein,we developed a novel Ca-Zn-silicate bioceramic implant with multi-functions to achieve the expected outcomes.The porous hardystonite(Ca2ZnSi2O7)scaffolds with triply periodic minimal surfaces(TPMS)-based pore architecture and graded pore size distribution from center to periphery(from 500 to 800μm or vice versa)were fabricated through the digital light processing(DLP)technique,and the scaffolds with homogeneous pores(500 or 800μm)were fabricated as control.The graded porous scaffolds exhibited a controlled bio-dissolving behavior and intermediate mechanical strength in comparison with the homogeneous counterparts,although all of porous implants presented significant antibacterial potential against S.aureus and E.coli.Meanwhile,the pore size-increasing scaffolds indicated more substantial cell adhesion,cell viability and angiogenesis-related gene expression in vitro.Furthermore,the gradually increasing pore feature exhibited a stronger blood vessel infiltrating potential in the dorsal muscle embedding model,and the spherical implants with such pore structure could achieve complete vascularization within 4 weeks in the eyeball enucleation rabbit models.Overall,our results suggested that the novel antibacterial hardystonite bioceramic with graded pore design has excellent potential as a next-generation orbital implant,and the pore topological features offer an opportunity for the improvement of biological performances in orbital reconstruction.