Coextrusion-Based 3D Plotting of Ceramic Pastes for Porous Calcium Phosphate Scaffolds Comprised of Hollow Filaments

Abstract

This paper demonstrates the utility of coextrusion-based 3D plotting of ceramic pastes (CoEx-3DP) as a new type of additive manufacturing (AM) technique, which can produce porous calcium phosphate (CaP) ceramic scaffolds comprised of hollow CaP filaments. In this technique, green filaments with a controlled core/shell structure can be produced by coextruding an initial feedrod, comprised of the carbon black (CB) core and CaP shell, through a fine nozzle in an acetone bath and then deposited in a controlled manner according to predetermined paths. In addition, channels in CaP filaments can be created through the removal of the CB cores during heat-treatment. Produced CaP scaffolds had two different types of pores with well-defined geometries: three-dimensionally interconnected pores (~360 × 230 μm2 in sizes) and channels (>100 μm in diameter) in hollow CaP filaments. The porous scaffolds showed high compressive strengths of ~12.3 ± 2.2 MPa at a high porosity of ~73 vol % when compressed parallel to the direction of the hollow CaP filaments. In addition, the mechanical properties of porous CaP scaffolds could be tailored by adjusting their porosity, for example, compressive strengths of 4.8 ± 1.1 MPa at a porosity of ~82 vol %. The porous CaP scaffold showed good biocompatibility, which was assessed by in vitro cell tests, where several the cells adhered to and spread actively with the outer and inner surfaces of the hollow CaP filaments.

Porous Calcium Phosphate Ceramic Scaffolds with Tailored Pore Orientations and Mechanical Properties Using Lithography-Based Ceramic 3D Printing Technique

“…Extrusion-based AM techniques can create three-dimensionally interconnected pore networks by depositing green ceramic filaments extruded through fine nozzles, according to predetermined printing paths [ 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 ]. In addition, they can readily tune the porosity and pore size of porous ceramic scaffolds simply by adjusting the distance between the deposited filaments, which provides tailored mechanical properties.…”

Additive manufacturing and performance of bioceramic scaffolds with different hollow strut geometries

“…In the past few years, several studies have presented methods to form hollow channels in printed scaffolds [14][15][16][17]. In several methods, hollow channels in scaffolds were achieved using sacrificial core materials that were subsequently removed [16]. Such methods are somewhat limited with regard to achievable structure and materials.…”

Coextrusion of Reaction‐Bonded Carbides by Robocasting

“…By printing a carbon core, hollow strut structures can be realized by burnout of the carbon content. Materials like alumina [ 26 ] or CaP [ 27 ] were already successfully printed in the course of biomedical application. Further, nonhollow structures like NiO‐coated alumina struts were printed.…”