Towards Indirect Tissue Scaffold Fabrication via Additive Manufacturing and Hydroxyapatite Mineralization

Unlike traditional stochastic scaffold fabrication techniques, additive manufacturing (AM) can be used to create tissue-specific three-dimensional scaffolds with controlled porosity and pore geometry. Directly fabricating scaffolds through AM methods is limited because of the relatively few biocompatible materials available for processing in AM machines. To alleviate these material limitations, an indirect fabrication method is proposed. Specifically, the authors investigate the use of Fused Deposition Modeling to fabricate scaffold patterns of varied pore size and geometry. The scaffold patterns are then mineralized with a biocompatible ceramic (hydroxyapatite). A heat treatment is then used to pyrolyze the pattern and to sinter the thin ceramic coating. The result is a biocompatible ceramic scaffold composed of hollow tubes, which may promote attachment of endothelial cells and vascularization [1]. In this paper, the authors explore the scaffold pattern fabrication and mineralization processes. Two scaffold pattern materials are tested [acrylonitrile butadiene styrene (ABS) and investment cast wax (ICW)] to determine which material is the most appropriate for scaffold mineralization and sintering. While the ICW could not be thoroughly mineralized despite a sodium hydroxide surface treatment, the ABS patterns were successfully mineralized following an oxygen plasma surface treatment. A 0.004 mm mineral coating was found on the ABS patterns that featured a strut offset of 0.3 mm, which is in the range of appropriate pore size for bone tissue engineering [2].Mechanical Engineerin