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

Abstract

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 SiO44- 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.