Preparation and characterization of keratin–chitosan composite film

Keratin–chitosan composite film was prepared by casting the mixed solution of both biopolymers in 75% acetic acid. Although keratin film without any additive is very fragile, 10–30 wt% of chitosan addition gave strong and flexible film (ultimate strength: 27–34 MPa, ultimate elongation: 4–9%). Glycerol (20 wt%) also afforded flexibility to keratin film (ultimate strength: 1 MPa, ultimate elongation: 28%). Further addition of chitosan to glycerol-containing keratin film increased the ultimate strength to 9–14 MPa but gave little effect on ultimate elongation. These data suggest that mechanical properties of keratin film are adjustable by appropriately adding chitosan and glycerol. Waterproof characteristics such as swelling behavior and mechanical properties after swelling were much ameliorated for the composite film compared with keratin and chitosan films, respectively. Furthermore, keratin–chitosan composite film as well as chitosan film decreased bacteria number when the bacteria suspension was treated with a film owing to the irreversible adsorption of bacteria onto the film. The composite film as well as keratin and chitosan films supported fibroblast attachment and proliferation, demonstrating to be a good substrate for mammalian cell culture.