Extrusion-based 3D co-printing: Printing material design and novel workflow for fabricating patterned heterogeneous tissue structures

Abstract

Extrusion-based 3D printing (E3DP) is commonly used both in in vitro and in situ biofabrication, due to the wide range of biomaterials and cells available and the low cost. However, it is challenging to fabricate such functional scaffolds due to limitations in ink performance, which must match the physicochemical and biological features of tissues. This study aims to bridge the gap via controlling the material distribution before printing. Here a new approach for preparing structured inks for E3DP is proposed. The feasibility is verified through ink preparation and process parameter optimization. These inks are fabricated by the integrated technology of casting and 3D printing. Computational fluid dynamics (CFD) simulation is employed to simulate the ink flow through the channels of printheads. The geometric parameters of these inks are determined by analyzing the cross section of the extruded fibers. Inks with core–shell cross section are investigated to clarify the effect mechanism of structured inks on printed fibers. Inks with symmetric cross section are exemplified to show the diverse printable structures. Finally, a novel workflow to the design and fabrication of structured printing materials for E3DP is presented. This approach may enrich E3DP while facilitating the fabrication of heterogeneous tissue structures.

Keywords

• Heterogeneous structures
• extrusion-based 3D printing
• Structured inks
• Mold casting
• Computational fluid dynamics
• Hydrogels