Polyelectrolyte Complex-Based Artificial Biofilms as Versatile Living Biomaterials

Bacterial biofilms, while recognized as promising functional biomaterials, are constrained by intricate growth dynamics, complex extracellular polymer compositions, and limited processability. Here, we address these challenges by employing polyelectrolyte complexes (PECs) to create artificial biofilms via a one-step synthesis with predefined extracellular composition and enhanced processability, achieving natural biofilm-like bacterial density and properties across diverse bacterial species. The PEC matrix confers robust bacterial protection, resisting antibiotic concentrations 1000-fold above the minimal inhibitory level, lyophilization, and acidic environments. Its shear-thinning behavior enables versatile processing via extrusion, molding, or coating. As recyclable biocatalysts, these biofilms preserve the enzymatic activity at elevated temperatures (up to 80 °C). In simulated probiotic delivery, they enhance bacterial survival under gastrointestinal-like conditions and offer tunable, composition-dependent release profiles, achieving therapeutic efficacy in a murine colitis model. This platform combines flexible fabrication with customizable functionality, establishing a versatile strategy for engineered living biomaterials with broad applications in biotechnology and biomedicine.