Polyelectrolyte Complex Hydrogels from Controlled Kneading and Annealing‐Induced Tightly Wound and Highly Entangled Natural Polysaccharides

Hydrogels usually are fabricated by using monomers or preexisting polymers in precursor solutions. Here, a polyelectrolyte complex biohydrogel (Bio‐PEC hydrogel) made from a precursor dough, by kneading, annealing, and crosslinking the dough of two oppositely charged polysaccharides, cationic chitosan quaternary ammonium salt (HACC) and anionic sodium hyaluronate (HA), photoinitiator (α‐ketoglutaric acid), crosslinker glycidyl methacrylate (GMA), and water of very small quantity is reported. Controlled kneading and annealing homogenized the dough with respect to transforming randomly distributed, individual polymer chains into tightly wound double‐stranded structures, which, upon UV irradiation, covalently sparsely crosslinked into a highly entangled network and subsequently, upon fully swollen in water, results in Bio‐PEC hydrogel, HACC/HA, exhibiting near‐perfect elasticity, high tensile strength, and high swelling resistance. Via the same kneading and annealing, tetracarboxyphenylporphyrin iron (Fe‐TCPP) metal nanoclusters are incorporated into HACC/HA to obtain photocatalytic, antibacterial, and biocompatible Bio‐PEC hydrogel composite, Fe‐TCPP@HACC/HA. Using SD rat models, the efficacy of Fe‐TCPP@HACC/HA in inhibiting Escherichia coli(E. coli) growth in vitro and the ability to promote wound healing and scar‐free skin regeneration in vivo, or its high potential as a wound dressing material for biomedical applications are demonstrated. This work demonstrates an approach to high tensile strength, toughness, and high swelling resistance polyelectrolyte complex biohydrogel (Bio‐PEC hydrogel) via the controlled kneading and annealing homogenized formation of tightly wound double‐stranded structures and sparsely covalently crosslinked into a highly entangled network. Tetracarboxyphenylporphyrin iron (Fe‐TCPP) is incorporated into Bio‐PEC hydrogel, showing favourable antibacterial activity and promoting wound healing and skin regeneration.