Fast Expandable Chitosan‐Fibers Cryogel from Ambient Drying for Noncompressible Bleeding Control and In Situ Tissue Regeneration

Abstract Hemorrhage control, especially noncompressible wound hemostasis, is a tremendous challenge in military injuries and other traumas worldwide. Here, a cryogelation strategy and subsequent solvent exchange are developed for the hydrogen bond‐induced self‐assembly of chitosan fibers and the production of fast expandable chitosan cryogel. Importantly, the ambient drying process facilitates the repeatable deformation performance of the shape‐memory cryogel with a response time of ≈1.7 s. Due to the capillary‐like structure of the cryogel and high hydrophilicity, rapid shape recovery is accompanied by 41 times water absorption ability. It is further demonstrated that chitosan cryogel is beneficial for in situ tissue regeneration by taking advantage of the biodegradability and biocompatibility of chitosan. Thus, chitosan cryogels prepared by this simple and benign method should have efficient hemostatic effect on noncompressible bleeding and severe fatal high‐pressure hemorrhage.