Biomimetic Design for a Dual Concentric Porous Titanium Scaffold with Appropriate Compressive Strength and Cells Affinity

In repairing or replacing damaged bones, a dual concentric porous titanium scaffold (P-Tix-y) has emerged as a promising bio-mimic design. Herein, various P-Tix-y were made and sintered with relatively dense (x = 10, 20, or 30% porosity) and loose (y = 45, 55, or 65 porosity) structures. Firstly, NaCl was used as the pore-forming additive and followed by a hydrothermal removal method. The compressive strength of the as-formed P-Ti-x_y and surface morphology, nanomechanical property, and cells' affinity on the cross-sectioned surface of P-Ti-x_y(CP-Ti-x_y) were then characterized. The results demonstrate that the compressive strength of P-Ti-10_45, P-Ti-20_45, or P-Ti-20_55 exhibits a relatively mild decline (e.g., in the range of 181 and 97 MPa, higher than the required value of 70 MPa) and suitable porosities for the intended structure. Nano-hardness on the solid surface of CP-Ti-x_y shows roughly consistent with that of CP-Ti (i.e., similar to 8.78 GPa), thus, the porous structure of CP-Ti-x_y remains mostly unaffected by the addition of NaCl and subsequent sintering process. Most of the surfaces of CP-Ti(x_y)exhibit high fibroblast (L929) cell affinity with low cell mortality. Notably, in the hFOB 1.19 cell adhesion and proliferation test, CP-Ti-20_55 and CP-Ti-20_65 reveal high cell viability, most probably relating with the assembly of dual porosities with interconnected pores. Overall, the sample P-Ti-20_55 provides a relatively load-bearable design with high cell affinity and is thus promising as a three-dimensional bio-scaffold.