Biomimicking the mechanical properties of native tissues is one of the key requirements of engineering tissue scaffolds, creating a need for materials and manufacturing processes with a high level of control over the mechanical properties of the scaffolds. To address this need, we present a 3D printable, composite hydrogel consisting of sodium alginate (SA), gelatin (GEL) and gum Arabic (GA), referred to herein as SA-GEL-GA hydrogel, whose mechanical properties can be controlled through tuning of applied cross-linking processes. Here, the aqueous solution of the three constituents is used as the bioink to 3D print porous scaffolds in a temperature-controlled extrusion-based printing process. 3D-printed scaffolds are then crosslinked through a multi-step approach, to achieve the gelation of GEL, ionic crosslinking of SA and GA, and covalent cross-linking of all three components are performed. Our results show that the inherent mechanical properties of SA-GEL-GA hydrogels can be controlled through the duration of the covalent crosslinking step. Specifically, the compressive elastic modulus of these scaffolds can be tuned within the 50-250 kPa range through combined effects of the scaffold pores size and covalent crosslinking step duration. The SA-GEL-GA bioinks were found to highly exhibit temperature-dependent rheology with elastic solid-like behavior below room temperature and a viscoplastic, shear thinning nature above 28 °C. Using a cooled build-plate and heated printhead, high resolution scaffolds were printed with filament diameter of 250 μm and extruded from a 100 μm diameter nozzle. The 3D printed and crosslinked scaffolds carried over 500% of their dry weight in water and can be dried and reswollen to over 400% of their dry weight. Finally, our degradation analysis showed that increased covalent cross-linking duration led to reduced long-term structural stability due to mechanical failure of the scaffolds. These results indicate that SA-GEL-GA hydrogels offer exciting opportunities for manufacturing customizable artificial tissue scaffolds with biomimicking mechanical properties, particularly for soft tissues.

3D printable hydrogels with tunable mechanical properties for tissue engineering

ACS Spring Meeting 2021

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.