A gradiently wettable bilayer hemostatic dressing composed of oppositely charged chitosan and alginate nanofibers and polycaprolactone nanofibers.

Conventional hemostatic dressings often suffer from excessive blood absorption and a propensity for leakage at the dressing/tissue junction, leading to large blood loss. Herein, we developed a Janus amphiphilic electrospun nanofibrous membrane (ENM) dressing for effectively controlling blood flow. It comprised a hydrophilic hemostatic layer of negatively charged poly(vinyl alcohol)@dopamine modified sodium alginate (PSD) core-shell nanofibers and positively charged poly(vinyl alcohol)@quaternized chitosan (PQCS) core-shell nanofibers, as well as a hydrophobic barrier layer of polycaprolactone (PCL) nanofibers. Upon contact with blood, the oppositely charged fibers in the hydrophilic layer fused together to arrest red blood cells (RBCs) and thereby forming blood clots, while simultaneously establishing robust tissue adhesion through synergistic hydrogen bonding and electrostatic interactions. In addition, the hydrophobic layer hindered blood diffusion via hydraulic compression, which effectively prevented the permeation of blood from the hydrophilic to the hydrophobic layer, thereby avoiding excessive blood loss by absorption. In vivo evaluations confirmed that the Janus PSD-PQCS/PCL ENM exhibited superior hemostatic efficacy compared to cotton gauze and QuikClot. The good hemostatic capability, antibacterial activity, hemo- and bio-compatibility of our Janus ENM suggest its potential as a promising hemostatic dressing.