Dextran-Mediated Control of Ice Crystallization in Polyphenol-Protein Fibril Networks for Freeze-Thawing-Stable Hydrogels with Anti-Inflammatory Activity.

Freeze-thawing (F-T) cycling compromises the structural integrity and functionality of biomacromolecular hydrogels due to uncontrolled water crystallization and ice-crystal growth. Herein, we identified dextran from screening different polysaccharides and synthetic polymers as an ideal ice-crystal modifier for protein amyloid fibril-polyphenol hydrogels. Formation of the ternary composite hydrogel and F-T resistance were positively dependent on dextran molecular weight and concentration, with a tolerance for exceeding 50 times F-T cycles. Low-temperature differential scanning calorimetry (DSC) and ice-crystal observation showed reduced freezable water and restricted ice growth in hydrogels, while rheology and microstructure characterization revealed enhanced strength and a denser, more uniform porous network after F-T treatment. These improvements were attributed to dextran-mediated network confinement, which imposed strong constraints on ice formation and growth. Furthermore, the hydrogel retained in vitro and in vivo anti-inflammatory activities with high biocompatibility. This work provided a polysaccharide-modulated ice templating for hydrogel engineering in bioactive delivery.