3D-Printed Ti6Al4V Scaffolds with Graded Triply Periodic Minimal Surface Structure for Bone Tissue Engineering

The repair of bone defect needs bionic scaffolds that meet biomechanical and bio-structural requirements. The triply periodic minimal surface (TPMS) scaffold, with a radial gradient porosity distribution mimicking natural bone, is a potential high-performance biomaterial for orthopedic implants. In this paper, TPMS scaffolds with various radial gradient porosities, which resembled the graded structure of human bone, were prepared by selective laser melting (SLM) with Ti6Al4V as a building material. The microstructure characteristics, mechanical properties and cell behaviors of scaffolds were systematically analyzed. Metallographic structure results showed that the grain size exhibited a radial decreasing porosity from the outer layer to the inner layer. The average porosity of all as-built samples ranged from 55% to 71%, and the average pore sizes ranged from 333μm to 674μm. The compression tests showed that the Young’s modulus (2.7-7.4GPa) and yield strength (233-520MPa) of all samples were sufficient to satisfy the requirements of human nature bone. Additionally, the cell viability of scaffolds by measuring the cell distribution and proliferation after 48h, 72h and 96h showed expected biocompatibility. The significance of this work is to improve the understanding of the effect of design parameters on the mechanical properties and cell growth of the scaffolds.