Functionally graded triply periodic minimal surface scaffold of HA-Al2O3 via Vat photopolymerization 3D printing

Hydroxyapatite (HA) is widely used in scaffolds due to its high similarity in the composition to natural bone. However, the weak and fragile characteristics of synthetic HA limit its application. The strength of HA can be increased by the incorporation of alumina (Al2O3) to obtain composites with extraordinary compressive strength and biocompatibility. HA-Al2O3 composites with different ratios were prepared by Vat photopolymerization 3D printing, and their shrinkage, porosity, phase composition and biocompatibility were systematically investigated. In addition, the Diamond structure of the scaffold was chosen to achieve the trade-off relationship between compressive strength and porosity. The results suggest that the HA-Al2O3 composite with 20 vol% HA possesses the maximum compressive strength and 60 vol% HA has optimal biocompatibility. A compositional gradient scaffold from 60 vol% HA and 20 vol% HA was proposed to satisfy different needs of the different parts in scaffold for biocompatibility and compressive strength. The HA-Al2O3 gradient scaffold achieves a preferable compressive strength of 13.7 MPa while possessing gradient biocompatibility.