Self-Healing Hydrogels and Cryogels from Biodegradable Polyurethane Nanoparticle Crosslinked Chitosan

Area of Science:

• Biomaterials Science
• Polymer Chemistry
• Tissue Engineering

Background:

• Hydrogels are crucial in tissue engineering due to their water retention and soft nature.
• Developing hydrogels with controlled degradation, environmental responsiveness, and injectability remains a challenge.

Purpose of the Study:

• To synthesize biodegradable difunctional polyurethane (DFPU) nanoparticles.
• To utilize DFPU as crosslinkers for chitosan (CS) to create novel self-healing hydrogels and cryogels.
• To evaluate the properties and biocompatibility of the resulting hydrogels for biomedical applications.

Main Methods:

• Eco-friendly waterborne synthesis of DFPU nanoparticles using glyoxal.
• Crosslinking of chitosan with DFPU via Schiff base linkages at room temperature.
• Formation of cryogels by freezing at -20 °C.
• Assessment of hydrogel properties including self-healing, injectability, pH/amine sensitivity, degradation, and biocompatibility through rheology and rat implantation.

Main Results:

• Successfully synthesized DFPU nanoparticles and formed self-healing hydrogels and cryogels with chitosan.
• Hydrogels demonstrated excellent self-healing properties (≈100% recovery) and injectability.
• Gels exhibited sensitivity to low pH and amine-containing molecules.
• Degradation rates were tunable by altering DFPU oligodiols.
• Cryogels showed low immune response in rat implantation studies.

Conclusions:

• Biodegradable DFPU nanoparticles provide a versatile platform for crosslinking biomacromolecules like chitosan.
• The dynamic Schiff reaction enables the creation of self-healing and injectable hydrogels and cryogels.
• These materials hold significant potential for diverse biomedical applications in tissue engineering.