Collocalia birds inspired Janus-structured bandage with strong wet tissue adhesion for rapid hemostasis and wound healing

Powdered hemostatic agents, when encountered with high blood pressure bleeding, are prone to being washed away by the blood flow, and there is a risk of entering the blood vessel to cause thrombosis. Fibrous membrane hemostatic bandages have poor adhesion to the wound and require prolonged press to stop bleeding, which may lead to ischemic necrosis of the tissue. Here, inspired by Collocalia birds to prepare cubilose, we propose a technique that large-particles of self-gelling powders are poured upon nanofibers during the spinning flight path and get Janus composite nanofiber membrane in one step. This Janus structure is an asymmetric wettability structure. The hydrophilic side achieved blood coagulation within 1 min by concentrating coagulation factor. The hydrophobic side is 99.99% free of bacteria and prevents bleeding. In addition, this membrane material has strong adhesion and can gel at 5.3 s, especially it does not need to wipe up the blood on the wet tissue beforehand. It exhibits firm adhere to the bleeding site, and can withstand the bursting pressure of 176 mmHg, much higher than the normal systolic blood pressure of the human body. Compared with medical gauze and commercially available gelatin hemostatic sponges, the hemostasis time is reduced to 1/5 (1.16 ± 0.28 min) and the blood loss is reduced to 1/3 (111 ± 11 mg). Moreover, this membrane has potential to be prepared in a large scale because of electro-blown spinning, and is expected to become a new commercially available material for hemostasis in the future.