Biphasic Calcium\nPhosphate Ceramic Scaffold Composed\nof Zinc Doped β‑Tricalcium Phosphate and Silicon Doped\nHydroxyapatite for Bone Tissue Engineering

The rapid repair of bone defects remains a significant\nclinical\nchallenge to this day. To address this issue, a 3D-printed biphasic\ncalcium phosphate (BCP) scaffold consisting of 40 wt % hydroxyapatite\n(HA) and 60 wt % β-tricalcium phosphate (β-TCP) was created.\nSilicon and zinc were incorporated into HA and β-TCP, respectively,\nto enhance the angiogenic and osteogenic properties of the BCP scaffold.\nThe physicochemical properties, <i>in vitro</i> cell responses,\nand bone defect repair efficacy of the modified BCP scaffold were\ncomprehensively investigated. Results showed that the fabricated scaffold\npossessed a 3D interconnected pore structure. Zinc doping enhanced\nthe sintering of the BCP scaffold, increased its density and strength,\nbut decreased its degradation rate. Conversely, silicon doping had\nthe opposite effect. The modified scaffold was capable of a gradual\nrelease of zinc/silicon ions, which promoted the proliferation and\ndifferentiation of cells. Specifically, the scaffold doped with zinc\nsignificantly promoted the osteogenic differentiation of stem cells.\nMoreover, co-doping with silicon and zinc synergistically promoted <i>in vitro</i> angiogenesis, with BCP-3 (doped with 2.5 mol %\nzinc and 4 mol % silicon) exhibiting the best pro-angiogenic activity.\nBCP-3 significantly induced regeneration of blood vessels and bone\ntissue <i>in vivo</i>, indicating its potential to accelerate\nthe process of bone defect repair.