Extensile Active Hydrogels Driven by Living FtsZ Polymers

Abstract Embedding living polymers that consume chemical energy into synthetic gels offers a route to soft materials that self‐regulate their mechanical state. Here, The bacterial cytokinetic protein FtsZ is integrated within a polyacrylamide network to create an active extensile hydrogel. Upon post‐gelation activation with Mg ² ⁺ and GTP, FtsZ filaments treadmill and exert internal stresses that drive isotropic swelling and mechanical softening. These responses is described using a Flory–Rehner swelling framework, where activity‐induced volume expansion lowers the polymer volume fraction and, consequently, the elastic modulus. Normalizing the measured moduli to the FR baseline isolates an additional, rate‐dependent softening that arises from living FtsZ polymer dynamics. Rheological analysis reveals that biochemical energy input modulates the elastic state of a pre‐formed network through active swelling and strain‐dependent fluidization, establishing a minimal model for living‐polymer‐driven soft materials.