Extensile Active Hydrogels Driven by Living FtsZ Polymers.

Area of Science:

• Materials Science
• Biomaterials Engineering
• Polymer Chemistry

Background:

• Synthetic gels offer tunable properties but lack self-regulation.
• Living polymers can perform dynamic functions, but integrating them into synthetic materials is challenging.
• Controlling mechanical states of soft materials via internal activity is an emerging area.

Purpose of the Study:

• To develop a self-regulating soft material by embedding living polymers into a synthetic hydrogel.
• To investigate the mechanical responses of such active hydrogels to biochemical activation.
• To establish a minimal model for living-polymer-driven soft materials.

Main Methods:

• Integration of the bacterial cytokinetic protein FtsZ into a polyacrylamide network.
• Post-gelation activation using magnesium ions (Mg2+) and guanosine triphosphate (GTP).
• Characterization using Flory-Rehner swelling framework and rheological analysis.

Main Results:

• Activated FtsZ filaments exhibited treadmilling, inducing internal stresses.
• These stresses led to isotropic swelling and significant mechanical softening of the hydrogel.
• A rate-dependent softening, distinct from swelling effects, was attributed to FtsZ dynamics.

Conclusions:

• Biochemical energy input can dynamically modulate the elastic state of pre-formed synthetic networks.
• Active swelling and strain-dependent fluidization are key mechanisms in these living-polymer-driven materials.
• This work establishes a foundational model for active soft materials with self-regulating mechanical properties.