An Extracellular Matrix-like Surface for Zn Alloy to Enhance Bone Regeneration

Zn-based alloys are promising biodegradable implants for bone defect repair due to their good mechanical performance and degradability. However, local Zn²⁺ released from Zn-based implants can seriously affect adhering cell behaviors as well as new bone formation on implant surfaces. To address this issue, we have fabricated a bone-mimetic extracellular matrix (ECM)-like surface on Zn-1Ca implants using a hybrid process of anodization, hydrothermal treatment (HT), and fluorous-curing. The ECM-like surface consisted of Zn₂SiO₄ nanorods layered with collagen I (Col-I). The Zn₂SiO₄ nanorods were hemicrystallized and transformed by the reaction of Zn(OH)₂ and SiO₄^4- during the HT. The Zn₂SiO₄ nanorods effectively protected the substrate from corrosion; the Col-I layer decreased the degradation of Zn₂SiO₄ nanorods and further reduced Zn²⁺ release into the medium. This ECM-like surface generated a microenvironment with appropriate Zn²⁺ levels, nanorod-like topography, and Col-I. It significantly improved adhesion, proliferation, and differentiation of osteoblasts on implant surfaces and vascularization of endothelial cells in the extract medium. The in vivo results are in good agreement with in vitro tests, with the ECM-like surface significantly enhancing new bone formation and bone-implant contact compared to the bare implant surface. Overall, this bone-mimetic ECM-like material of Col-I layered Zn₂SiO₄ nanorods is a promising scaffold that promotes the bone regeneration of Zn-based implants.