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 800 μm or vice versa) were fabricated through the digital light processing (DLP) technique, and the scaffolds with homogeneous pores (500 or 800 μm) 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.