Highly Stretchable and Notch-Insensitive Hydrogel Based on Polyacrylamide and Milk Protein

Area of Science:

• Biomaterials Science
• Polymer Chemistry
• Tissue Engineering

Background:

• Protein-based hydrogels are promising for biomedical uses due to biocompatibility and abundance.
• A key limitation is their inadequate mechanical strength, hindering practical applications.
• Developing robust protein hydrogels is crucial for advancing regenerative medicine.

Purpose of the Study:

• To engineer a highly stretchable and notch-insensitive hydrogel.
• To enhance the mechanical properties of protein-based hydrogels.
• To explore synergistic effects between casein micelles and polyacrylamide networks.

Main Methods:

• Integration of casein micelles into polyacrylamide (PAAm) networks.
• Fabrication of casein-PAAm hybrid hydrogels.
• Characterization of mechanical properties, including uniaxial tension and fracture energy.

Main Results:

• Casein-PAAm hybrid gels demonstrate exceptional stretchability, exceeding 35 times their initial length.
• The hybrid gels exhibit high toughness and notch insensitivity, with a fracture energy of ~3000 J/m².
• A novel energy dissipation mechanism involving casein micelle friction and plastic deformation was proposed.

Conclusions:

• Casein-PAAm hybrid hydrogels offer superior mechanical properties compared to traditional protein hydrogels.
• The synergistic integration of casein micelles significantly enhances hydrogel performance.
• These findings pave the way for advanced biomaterials in tissue engineering and beyond.