Mechanically strong triple network hydrogels based on hyaluronan and poly(N,N-dimethylacrylamide)

Area of Science:

• Biomaterials Science
• Polymer Chemistry
• Biomedical Engineering

Background:

• Hyaluronan (HA) hydrogels are attractive for biomedical use due to their natural origin and biological functions.
• However, native HA hydrogels suffer from poor mechanical properties, including brittleness and dissolution in physiological environments, limiting their load-bearing capacity.

Purpose of the Study:

• To engineer robust and less degradable hyaluronan-based hydrogels for demanding biomedical applications.
• To enhance the mechanical strength and fracture resistance of HA hydrogels through a triple-network (TN) approach.

Main Methods:

• Sequential gelation reactions were employed to synthesize triple-network (TN) hydrogels.
• Hyaluronan (HA) with varying degrees of methacrylation formed the brittle first network.
• Poly(N,N-dimethylacrylamide) (PDMA) constituted the ductile second and third networks.

Main Results:

• The developed TN hydrogels exhibit high water content (81-91%) while sustaining compressive stresses over 20 MPa and Young's moduli up to 1 MPa.
• Tuning HA methacrylation in double-network hydrogels yielded fracture stress above 10 MPa and 96% fracture strain.
• The TN approach significantly enhanced fracture stress to over 20 MPa by increasing the ratio of ductile to brittle components.

Conclusions:

• Triple-network hydrogels based on HA and PDMA demonstrate superior mechanical properties, overcoming the limitations of traditional HA hydrogels.
• The TN structure effectively hinders macroscopic crack propagation, maintaining gel integrity even after internal fracturing.
• These findings highlight the potential of TN hydrogels for load-bearing biomedical applications requiring high strength and durability.