Biomimetic superparamagnetic gelatin/chitosan asymmetric fibrous membrane for accelerating wound healing under static magnetic field

The single structure, poor mechanical properties, and low biological activity of wound dressings usually lead to unsatisfactory treatment effects. Gelatin and chitosan possess excellent biofunction, but they lack sufficient mechanical support. Magnetic biomaterials and magnetic fields have shown surprising tissue repair potential. Herein, inspired by the skin structure and considering the bioactive composition, a superparamagnetic asymmetric membrane was constructed by incorporating gelatin, chitosan, and magnetic Fe₃O₄ nanoparticles. The proposed membrane exhibited a high degree of asymmetry, achieving functional diversification. The surface of the top layer was highly hydrophobic as an isolation barrier. The top layer consisted of dense fibrous chitosan with high mechanical strength and excellent antibacterial properties. The bottom layer was composed of gelatin sponge with distributed magnetic nanoparticles, possessing high porosity and swelling ratio to effectively absorb tissue exudates and support cell growth. Furthermore, the membrane demonstrated significant promotion of human dermal fibroblast proliferation under a static magnetic field. In a full-thickness mouse skin wound model, the membrane effectively accelerated wound healing with reduced wound area, abundant collagen disposition, and enhanced vascularization. Therefore, the superparamagnetic gelatin/chitosan asymmetric membrane with a biomimetic structure and function exhibits remarkable superiority and provides a promising approach to effective wound healing.