Silk Fibroin-Based Shape-Memory Organohydrogels with Semicrystalline Microinclusions

Area of Science:

• Materials Science
• Biomaterials Engineering
• Polymer Chemistry

Background:

• Traditional emulsifiers can be toxic and environmentally harmful.
• Silk fibroin (SF) is a natural protein with self-emulsifying properties.
• Developing advanced hydrogels with tunable mechanical and shape-memory functions is crucial for various applications.

Purpose of the Study:

• To design and synthesize novel organohydrogels (OHGs) using silk fibroin (SF) as a green emulsifier.
• To create high-strength, shape-memory OHGs with enhanced mechanical properties and cytocompatibility.
• To explore SF's potential as a sustainable alternative to chemical emulsifiers in emulsion-templated material synthesis.

Main Methods:

• Fabrication of oil-in-water emulsions using SF as a self-emulsifier and n-octadecyl acrylate (C18A) monomer.
• Stabilization of emulsions via ethanol-induced SF gelation (beta-sheet transition).
• In situ UV-initiated polymerization of C18A droplets to form organogel phases within the SF hydrogel matrix.

Main Results:

• Successfully synthesized stable oil-in-water emulsions and subsequent organohydrogels (OHGs) without external emulsifiers.
• Achieved high-strength OHGs with a Young's modulus up to 4.3 MPa, compressive strength up to 2.5 MPa, and toughness up to 0.68 MPa.
• Demonstrated switchable viscoelasticity and mechanics, along with good cytocompatibility and shape-memory function.

Conclusions:

• Silk fibroin is a versatile and green self-emulsifier for creating complex emulsion-templated materials.
• The developed organohydrogels exhibit superior mechanical properties and shape-memory capabilities.
• These findings highlight the potential of SF-based organohydrogels for advanced applications in tissue engineering and soft robotics.