Anna Duraj-Thatte1 Avinash Basavanna1 Arjirios Sourlis1 Neel Joshi1

1, Harvard University, Boston, Massachusetts, United States

Protein-based materials have been successfully used for several applications in nanotechnology, bioengineering and medicine. Their diverse biofunctions and unique structures make them ideal building blocks to create large scale functional materials. However, there are several challenges: scalable production, isolation, expensive synthesis and processing keep recombinant protein- based materials away from other most commercially successful large-scale living materials such as cellulose or mycelium-based materials.
To tackle this problem, we developed a novel method for the rapid biosynthesis of tailored hydrogels in a single step, directly from bacterial culture, using a protocol that requires no protein purification. The hydrogel scaffold is based on the engineered extracellular matrix protein CsgA, which self-assembles into a fibrous mesh-like network that is 4-7% of hydrogel mass.
Most importantly, by genetic engineering of CsgA protein we can modulate a range of rheological properties as well as incorporate any specific functional modules for desired applications. This unique method leaded us to create a novel viscoelastic and shear-thinning 3D printing inks that are entirely biofabricated by genetically engineered bacteria. Due to biofabrication process that we developed, this hydrogel can contain living bacteria capable of producing more living ink or living bacteria can be removed during fabrication. This novel bacterial ink can be used for printing complex large scale materials with specific functions.