Commercial Electrospinning Machine| Chitosan-based Janus dressing withasymmetric wettability for rapidhemostasis, antibacterial protection, andtissue regeneration in hemorrhagicwound management

Skin injuries caused by mechanical forces (e.g., cuts, abrasions) are often accompanied by tissue bleeding. Failure to achieve timely and effective hemostasis not only significantly delays the healing process but may also induce systemic complications such as coagulation disorders and shock. Therefore, rapid bleeding control is the core of managing such wounds. However, the repair of hemorrhagic wounds involves complex processes, typically including post-hemostasis inflammatory responses, cell proliferation, and tissue remodeling. Although existing hemostatic dressings can effectively achieve rapid hemostasis, their single functionality makes it difficult to simultaneously meet the critical demands of rapid hemostasis, efficient antibacterial action, and tissue regeneration. Thus, developing multifunctional hemostatic dressings that combine rapid hemostasis, real-time antibacterial efficacy, and tissue regeneration remains challenging.  

Recently, Associate Professor Yadong Tang’s team at Guangdong University of Technology published their latest research, *"Chitosan-based Janus dressing with asymmetric wettability for rapid hemostasis, antibacterial protection, and tissue regeneration in hemorrhagic wound management,"* in *Carbohydrate Polymers*. Inspired by natural skin structure, the team successfully prepared a chitosan-based Janus dressing (CM@PS/TZ) with asymmetric wettability using electrospinning and freeze-drying techniques.  

The outer layer of this Janus dressing incorporates antibacterial zeolitic imidazolate framework-8 (ZIF-8) into thermoplastic polyurethane (TPU) nanofiber membranes via electrospinning, forming a hydrophobic barrier (water contact angle >120°) with antibacterial properties. This layer not only physically blocks bacterial invasion but also continuously releases Zn²⁺ ions for chemical antibacterial effects, achieving over 99% inhibition rates against *Escherichia coli* and *Staphylococcus aureus*. The inner layer consists of a hydrophilic sponge composed of methacrylated chitosan (CSMA) loaded with polydopamine-modified silica (PDA-SiO₂) nanoparticles. Here, CSMA promotes red blood cell and platelet aggregation through positive charges for rapid hemostasis, while PDA’s phenolic hydroxyl network effectively scavenges free radicals (DPPH clearance rate increased to 51.16%). Meanwhile, SiO₂ nanoparticles enhance the dressing’s hemostatic performance and release silicon ions to activate the VEGF pathway, promoting vascular regeneration. This synergistic design of a hydrophobic antibacterial outer layer and a hydrophilic hemostatic inner layer provides a comprehensive solution for hemorrhagic wounds.  

Fig. 1: Design, fabrication, and application of CM@PS/TZ Janus dressing

The dressing features a bilayer structure with a hydrophilic CM@PS sponge layer and a hydrophobic TZ nanofiber membrane, with scanning electron microscopy (SEM) confirming tight interfacial bonding. Wettability tests showed that the TZ nanofiber membrane exhibits significant hydrophobicity (water contact angle >120°), while the CM@PS sponge layer displays good hydrophilicity (water contact angle <50°). Performance tests revealed that the Janus dressing has excellent water absorption, suitable mechanical strength, and sustained release of functional Si⁴⁺ (promoting angiogenesis) and Zn²⁺ (antibacterial) ions, indicating its suitability for hemorrhagic wound repair.  

Fig. 2: Physicochemical characterization of CM@PS/TZ Janus dressing  

Additionally, the Janus dressing demonstrated outstanding anti-bacterial adhesion and bactericidal capabilities. The hydrophobic outer layer physically blocks bacterial adhesion, while Zn²⁺ released from ZIF-8 disrupts bacterial membranes, achieving nearly 99% killing rates against Gram-negative (*E. coli*) and Gram-positive (*S. aureus*) bacteria. This dual mechanism of hydrophobic barrier and chemical sterilization establishes an efficient antibacterial defense system for wounds.  

Fig. 3: Anti-bacterial adhesion and bactericidal activity of CM@PS/TZ Janus dressing

Beyond its antibacterial properties, the chitosan-based Janus dressing exhibits excellent hemostatic performance. *In vitro* coagulation tests (BCI and clotting time) showed that the chitosan-based sponge significantly promotes clotting, with the PDA-SiO₂-incorporated group exhibiting lower BCI values and shorter clotting times. Mechanistic studies indicated that the sponge primarily facilitates rapid hemostasis by promoting platelet and red blood cell adhesion (>60% adhesion rate). Furthermore, PT and APTT tests suggested that the PDA-SiO₂-containing group may further enhance coagulation by activating the extrinsic coagulation pathway via SiO₂. Rat liver injury and tail amputation models further confirmed the dressing’s superior hemostatic effects: compared to gauze, blood loss was reduced by 0.44 g and 0.23 g, respectively, and hemostasis time was shortened by 41.52 s and 59.47 s.  

Fig. 4: *In vitro* coagulation properties and mechanisms of CM@PS/TZ Janus dressing  

Fig. 5: *In vivo* hemostatic performance of CM@PS/TZ Janus dressing 

Finally, the research team evaluated the Janus dressing’s ability to promote healing in full-thickness skin wound models. Results showed that the CM@PS/TZ group had the fastest healing rate, achieving 95.78% wound closure by day 14. H&E, Masson, and CD31 staining confirmed that the CM@PS/TZ Janus dressing effectively prevents infection, increases collagen deposition (20.82% higher than the control group), and promotes angiogenesis (CD31 expression 3.10% higher than the control group), thereby accelerating wound healing. These findings demonstrate that the CM@PS/TZ Janus dressing integrates antibacterial, hemostatic, and pro-angiogenic multifunctional properties, providing an innovative solution for hemorrhagic wound treatment.  

Fig. 6: CM@PS/TZ Janus dressing’s wound healing results  

Fig. 7: Histological analysis of wound tissue 

Paper link:[https://doi.org/10.1016/j.carbpol.2025.123891](https://doi.org/10.1016/j.carbpol.2025.123891)