Nature uses proteins as building blocks to create three-dimensional (3D) structural components (like spiderwebs and tissue) that are recycled within a closed loop. Furthermore, it is difficult to replicate the mechanical properties of these 3D architectures within synthetic systems. In the absence of biological machinery, protein-based materials can be difficult to process and can have a limited range of mechanical properties. Herein, we present an additive manufacturing workflow to fabricate tough, protein-based composite hydrogels and bioplastics with a range of mechanical properties. Briefly, methacrylated bovine-serum-albumin-based aqueous resins were 3D-printed using a commercial vat photopolymerization system. The printed structures were then treated with tannic acid to introduce additional non-covalent interactions and form tough hydrogels. The hydrogel material could be sutured and withstand mechanical load, even after immersion in water for 24 h. Additionally, a denaturing thermal cure could be used to virtually eliminate rehydration of the material and form a bioplastic. To highlight the functionality of this material, a bioplastic screw was 3D-printed and driven into wood without damage to the screw. Moreover, the 3D-printed constructs enzymatically degraded up to 85% after 30 days in pepsin solution. Thus, these protein-based 3D-printed constructs show great potential for biomedical devices that degrade in situ.
Keywords: 3D printing; bioplastics; bovine serum albumin; protein-based materials; tannic acid; tough hydrogels.