Preparation and in vitro degradation behavior of biodegradable porous Zn-Li-Ca alloy bone repair scaffolds

Porous pure Zn alloy scaffolds are often used for bone defects, but their clinical effects are limited due to poor mechanical properties and uneven degradation. In this study, porous Zn-Li-Ca alloy scaffolds with 70 % porosity were prepared by pressure infiltration method with 450-600 mu m NaCl particles were used as pore-making agent. The effect of pore structure and the content of Ca element on, mechanical properties, degradation and weight loss of porous Zn alloy scaffolds soaked in simulated body fluids (SBF) for 4 weeks were studied. The results showed that the Zn alloy scaffolds prepared by spherical sodium chloride has high pore connectivity, and the yield strength and elastic modulus of Zn-0.8Li-0.8Ca reach 35.80 +/- 1.89 MPa and 2.45 +/- 0.19 GPa, respectively. Compared with the pure Zn alloy scaffolds, the yield strength was increased by 18.5 times, the elastic modulus was increased by 9 times, which meets the mechanical requirements of human cancellous bone. Compared with Zn-0.8Li alloy scaffolds, the weight loss rate and degradation rate at 4 weeks reached 7.51 % and 0.21 mm/y, respectively. In vitro studies showed that the addition of Ca element weakened the formation of Li2CO3 protective layer and accelerated the degradation rate of the scaffold. The problem of slow degradation rate of Zn-Li alloy was solved, which laid a foundation for subsequent in vivo implantation experiments. The results of this study indicate that the porous biodegradable Zn-based scaffold has great application potential in bone defects