3D Printed Templating of Extrinsic Freeze-Casting for Macro-Micro Porous Biomaterials

As with most biological materials, natural bone has hierarchical structure. Microstructural features of compact bone are of various length scales. Its porosity consists of larger osteons (~100 μm diameter) and vascular channels, as well as smaller lacuna spaces (~10 μm diameter). In this study, the freeze-casting process used to form biocompatible porous scaffolds (made with hydroxyapatite, HA) has been improved to mimic the intrinsic hierarchical structure of natural bone by implementing an extrinsic 3D printed template. The results of pore characterization showed that this novel combined method of 3D printing and freeze-casting is able to produce porosity at multiple length scales. Non-porous, micro-porous (created with freeze-casting alone), and macro-micro porous (created with freeze-casting and 3D printed templating) scaffolds were compared as substrates to evaluate cellular activities using osteoblast-like MG63 cell lines. The number of cells oriented parallel to the HA wall structures in the freeze...