Bio-inspired all-wool keratin composites: A self-reinforcing strategy toward sustainable high-performance materials

Self-reinforced composites are sustainable alternatives to conventional materials. This material has a wide range of applications in fields such as aerospace, automotive manufacturing, electronic components, and biomedicine. However, issues such as difficulties in recycling and environmental pollution have constrained its sustainable development. Wool fiber has a multi-scale cortical cell architecture that combines a hierarchical structure with inherent biocompatibility and biodegradability. In this study, cortical cells extracted from wool were employed as the reinforcing agents when combined with a wool keratin matrix to fabricate a fully keratin-based self-reinforced composite. This work first investigates the dispersion stability of cortical cells within a keratin solution and identified the optimal processing conditions for forming a stable and homogeneous dispersion of cortical cells. The properties of both the cortical cells and the resulting self-reinforced composite were characterized. These results showed that adding cortical cells enhanced the mechanical properties of the composite, with a 304.13 % increase in tensile strength compared with keratin films. The material also exhibited a water absorption ratio of 4.93, a water retention ratio of 4.50, and a water vapor transmission rate of 2292.22 g/m², indicating its excellent air and moisture permeability. The in vitro blood coagulation index of this membrane reached 0.27, demonstrating favorable hemostatic and coagulative properties. It was also completely degraded by biological enzymes, making it an eco-friendly and sustainable material. This research provides new ideas for replacing composite reinforcements made from non-renewable resources and expands the biomedical application potential of biobased materials.