Biosynthesized Silk-Amyloid-Mussel Proteins as Dissolution Recyclable Materials With Tunable Supercontraction

Area of Science:

• Biomaterials Science
• Polymer Chemistry
• Sustainable Materials

Background:

• Dissolution recycling is a promising strategy for material regeneration and reducing greenhouse gas emissions.
• Most polymers are not practically recyclable by dissolution due to strong intermolecular forces hindering solvent interaction.
• Protein-based materials (PBMs) offer potential but require balancing mechanical strength with recyclability.

Purpose of the Study:

• To develop high-performance, dissolution-recyclable protein-based materials (PBMs).
• To establish design principles for creating PBMs that balance mechanical performance with recyclability.
• To demonstrate the feasibility of producing versatile, sustainable, and recyclable protein materials.

Main Methods:

• Utilized protein engineering and synthetic biology to design silk-amyloid-mussel (SAM) protein hybrids.
• Engineered SAM fibers (SAM_HY) with amorphous domains for solvent ingress and crystalline domains for mechanical strength.
• Employed aqueous formic acid for rapid (<1 h), energy-efficient dissolution and recycling.

Main Results:

• SAM_HY fibers demonstrated exceptional tensile strength (401 ± 40 MPa) and toughness (124 ± 38 MJ/m^-3).
• Materials exhibited minimal supercontraction (2.2% ± 1.9%) under high humidity (>90%).
• Recycled fibers retained structural integrity and mechanical performance over multiple cycles; recycled protein formed robust hydrogels with strong underwater adhesion.

Conclusions:

• Established fundamental design principles for recyclable PBMs by engineering SAM protein hybrids.
• Demonstrated full recyclability of high-performance PBMs through an energy-efficient dissolution process.
• Showcased the potential of recycled SAM_HY for creating versatile, sustainable, and mechanically robust materials.