Direct 3D Printing of Biomimetic Bioceramic Scaffolds by Cement Routes

Bioceramic-based 3-dimensionaly constructed structures and scaffolds are widely used for hard tissue engineering applications and as hard tissue analogs. Robocasting, where a bioceramic powder-binder combination in paste form is used as feed material can be used to develop 3D preforms. The hardening and shape preservation of the printed structures is usually achieved by subsequent polymerization of the organic component. In this study, a novel hybrid printing paste mainly composed of calcium phosphate cement (CaPC) has been developed to achieve <i>in situ</i> hardening during printing process. The cement component is a-tricalcium phosphate(Ca₃(PO4)₂), which readily converts to hardened hydroxyapatite (Ca₁₀(PO₄)₆(OH)₂ or HAp) upon hydration. The hydration product in a calcium-deficient HAp, in that sense it offers higher bioactivity and osteoconductive property as it is resembling chemistry of natural bone mineral better than any other CaP. Parametric printing studies has been performed to to determine optimal formulation of the printing paste. Meanwhile, validation of the processing approach, i.e. cement-conversion kinetics, HAp formation efficiency/extent, shape preservation for 3D-printed structures, mechanical properties has been examined. In addition, a microstructural modification approach to control and alter microporosity adaptable to 3D-printing process by incorporation of an inorganic pore generator has been demonstrated. .