The gelation of silk fibroin (SF) aqueous solution cross-linked by externally induced β-sheets generally takes longer times, and requires relatively strict conditions, limiting their biomedical application possibilities. Here, a simplified and straightforward strategy is proposed to induce superfast gelation of SF by a biocompatible Food and Drug Administration-approved amino acid surfactant, ethyl lauroyl arginine hydrochloride (LAE). The gelation time is as short as 15 s at 60 °C and falls within 1 min around body temperature. The distinct pathway and thermodynamics of superfast gelation of SF is deciphered, and three important factors including superfast and complete unfolding, heterogeneous nucleation seeds, and faster formation of more β-sheets that are crucial for superfast SF assembly are revealed. The LAEinduced in situ superfast gelation mechanism is first harnessed to fabricate an injectable antibacterial biodegradable hemostatic hydrogel for treatment of noncompressible liver bleeding. The amphiphilicity of LAE and superfast gelation is exploited to quickly entrap different sizes of air bubbles in the upper and lower part of the hydrogel, which is then lyophilized to form an asymmetric hierarchical porous SF-LAE sponge, where the large pores serve to drain blood, and dense pores prevent the outflow of blood to seal the wound.

Indwelling needles have been widely used in clinic for their advantage in reducing the pain and discomfort of vein caused by repeated punctures. Achieving anticoagulation and hemostasis on one single...