3D Printing of Biohybrid Silica Composites

Recently, additive manufacturing has emerged as a technique to fabricate engineered living materials (ELMs). Most 3D printed ELMs are composites of polymers and living cells, and inorganic-organic living composites have not been widely explored. Here, we 3D print fibers composed of the fungus, Aspergillus niger, into granular hydrogel matrices swollen in liquid growth media. The A. niger cells are engineered to express silicatein on the cell surface, which acts as a template for silica mineralization. After incubation, printed fungal spores display radial hyphal growth, extending from the core printed fiber. The radial growth of hyphae depends on oxygen and nutrient availability. We characterize the mechanical properties of the fibers pre- and post-biomineralization. Overall, this work demonstrates that material properties of 3D printed inorganic-organic engineered living materials can be tuned by oxygen and nutrient availability.