Fabrication, in vitro and in vivo properties of porous Zn–Cu alloy scaffolds for bone tissue engineering

Abstract

Zn-based porous scaffolds have attracted increasing attention in the field of bone tissue engineering. In this study, the air pressure infiltration method (APIM) was employed to prepare porous Zn-xCu (x = 0, 1, 2, and 3 wt%) scaffolds. The porous structure, microstructure, mechanical properties, corrosion behavior, antibacterial properties and cytotoxicity of these porous scaffolds were systemically investigated. The pure Zn and the Zn–2Cu porous scaffolds were selected for the animal experiment to evaluate feasibility as orthopedic implant material using micro-computed tomography, histological analysis, and blood biochemical indicators. Uniformly distributed pores with an average size of 275 μm were confirmed in the Zn–Cu scaffolds. The plateau stress σy of the Zn–Cu scaffolds at 3% deformation was 2.55–51.15 MPa, and the elastic modulus E was 0.34–3.75 GPa. Hence, the mechanical properties of these scaffolds were similar to those of human cancellous bone. Porous Zn-xCu scaffolds exhibited a uniform corrosion morphology in simulated body fluid solution, and the addition of Cu facilitated the corrosion progress of the scaffold. Porous Zn-xCu scaffolds exhibited an effective antibacterial property against S. aureus and E.coli. The antibacterial activity increased with the increasing Cu contents. The porous Zn-xCu scaffolds exhibited good cytocompatibility at a low extract's concentration (25%), and the Zn–Cu scaffold exhibited a better cytocompatibility to MC3T3 pre-osteoblast cells than L-929 cells. Both pure zinc and Zn–2Cu porous scaffolds showed good biocompatibility in vivo. The blood biochemical parameters of SD rats within six months after operation were all within the acceptable range, and the implants had no side effect on the liver and kidney functions of SD rats.