A Core-shell Structured VEGF-SiO2@ZnO Nanorod Array for Enhancing Osteogenesis of Zn-based Implants

Abstract

Excessive Zn2+ ions are released from Zn-based implants during their degradation, which induce cytotoxicity, affecting early osteogenesis. To address this issue, a core-shell structured nanorod array with ZnO as core and VEGF-loaded mesoporous SiO2 as shell was constructed on Zn-1Ca substrate by a hybrid process of hydrothermal treatment (HT), sol-gel method and impregnation. ZnO by HT could effectively protect the substrate from serious corrosion; mesoporous SiO2 further increases anti-corrosion properties of substrates and serves as carrier to load vascular endothelial growth factor (VEGF). The nanorod array improves behaviors of bone marrow stroma cells (BMSCs) and HUVECs due to the appropriate release of Zn and Si ions as well as VEGF. The separated effect of Zn and Si ions on osteogenesis of BMSCs and angiogenesis of HUVECs are confirmed respectively. The positive effect of nanorod array on new bone formation of Zn-1Ca implant is also demonstrated in vivo. Overall, this work provides a core-shell structured nanorod array to reduce degradation of Zn-based implant and accelerate its early biointegration by enhancing angiogenesis and new bone formation.