3D printed Nanohydroxyapatite/Polyamide 66 scaffolds with balanced mechanical property and osteogenic ability for bone repair

The biomaterial requirements for bone tissue repair are extremely strict. It not only requires the biomaterial to have good biocompatibility and biological activity, but also requires sufficient mechanical strength. Polyamide 66 (PA66) and nano-hydroxyapatite (n-HA) have been widely investigated in bone tissue engineering scaffold, however, its composites require further research. In this study, the 3D printing technology was utilized to fabricate personalized n-HA/PA66 bone tissue scaffold. The mechanical properties of n-HA/PA66 composite can be adjusted by configuring different raw material components and applying different porosity. It was found that 50 % porosity n-HA/PA66 composite scaffold showed a uniform porous structure and a compressive strength of 33.9 MPa. The composite scaffold also exhibited excellent biological properties while improving mechanical properties, in vitro cell tests indicated that the 3D printed n-HA/PA66 composite scaffold promoted differentiation of bone marrow mesenchymal stem cells (BMSCs) into osteoblasts. In in vivo animal model proved that the scaffold promoted endogenous bone regeneration in rabbit patellar bone defects, with newly formed bone volume of 20.9 % after two months of implantation. This research proposed a 3D printed polyamide/nano-hydroxyapatite composite with balanced mechanical property and osteogenic ability for customized bone tissue repair, and it has promising application prospects.