Polymerization of 3D Printable PEDOT:PSS Catalyzed by Cyanobacteria

Sustainable chemical synthesis is important to reduce hazardous reagents and minimize their environmental impact. Most biocatalytic approaches rely on purified enzymes or engineered microbes. In contrast, this study uses wild-type photosynthetic cyanobacteria to directly drive polymerization, harnessing naturally produced redox mediators for conductive-material synthesis. The biocatalytic polymerization of poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) by the cyanobacterium Synechococcus elongatus (PCC 7942) and its secreted byproducts is described herein. Polymer yield was modulated by growing cells in either continuous light or varied light/dark cycles, suggesting a link between the accumulation of redox mediators and reaction kinetics. Both whole-cell cultures and conditioned media derived from these cultures produced PEDOT:PSS. Treatment of the conditioned media with proteinase K and autoclaving still resulted in polymerization, indicating that the reaction is not enzyme-dependent. Viscosity measurements showed shear-thinning behavior of the resulting conductive ink, consistent with extrusion and printability by using direct ink writing printing. The material was optimized for printing into self-supporting 3D structures and exhibited an average conductivity of 1.19 × 10–5 S/cm. These findings demonstrate the potential of photosynthetic microbial byproducts as sustainable alternatives for polymer synthesis.