Photosynthetic Biomanufacturing in Mechanically Robust, 3D Printed Hydrogels.

Engineered living materials (ELMs) integrate synthetic polymers with engineered cells to create systems that sense, respond, and adapt to their environment. While promising as sustainable alternatives to traditional materials, ELMs remain underexplored for use with photoautotrophic organisms. In this study, we evaluate the viability of the cyanobacterium Synechococcus elongatus PCC 7942, which converts carbon dioxide into valuable chemicals using light energy, in three hydrogel matrices previously shown to support heterotrophic cells. S. elongatus remained viable and metabolically active only in a hydrogel formed from bovine serum albumin-conjugated acrylates. When engineered to produce 2,3-butanediol (23BDO), encapsulated cells generated 719 mg L-1 over four days. Incorporating cells increased the compressive modulus of the material, while accumulated 23BDO reduced it, indicating that bioproduction influences mechanical properties. Fluorescence imaging confirmed high viability and physical immobilization. These results establish that cyanobacteria-based ELMs can enable autotrophic chemical production while modulating material mechanics for sustainable applications.