Role of undenatured type II collagen in novel ternary interpenetrating polymer networks hydrogel based on structural modulation and properties characterization

This study delved into the role of undenatured type II collagen (C-Ⅱ) in κ-carrageenan (KC), konjac glucomannan (KGM) and C-Ⅱ ternary interpenetrating polymer network (IPN) hydrogel by structural modulation and properties characterization. The C-Ⅱ nanofibrils exhibited robust cross-linking with the KC/KGM primarily via intermolecular interactions and physical entanglement while retaining the native triple-helical conformation. Incorporating moderate levels of C-Ⅱ nanofibrils resulted in densification of the hydrogel network, significantly reducing pore sizes from 2.11 ± 0.64 to 0.52 ± 0.29 μm. The rigid KC/KGM first network and the flexible C-Ⅱ nanofibrils second network were interspersed, forming an effective "energy dissipation" mode, which enhanced the mechanical properties of hydrogels. In addition, the intermolecular interactions promoted a more uniform and stable distribution of hydrogen protons, and enhanced the water-holding capacity, swelling properties, freeze-thaw stability and thermal stability of hydrogel. However, excessive concentrations of C-Ⅱ nanofibrils led to aggregate formation, resulting in phase separation and negating the beneficial effects on hydrogel properties. These findings underscored the potential of C-Ⅱ nanofibrils in hydrogel design, offering a blueprint for developing functional hydrogels with tailored properties for food applications.