Surface properties of thin films based on the mixtures of chitosan and silk fibroin

Thin films by solvent evaporation from mixture of chitosan and silk fibroin were prepared. The interactions between components in the blend were studied by FIR spectroscopy. The surface properties of chitosan/silk fibroin blended films were investigated using the technique of Atomic Force Microscopy (AFM) and by means of contact angle measurements allowing the calculation of surface free energy. Measurements of the contact angle for diiodomethane (D), and glycerol (G) on the surface of chitosan films and chitosan/silk fibroin films were made and surface free energy was calculated. The surface of thin films based on the blends of chitosan and silk fibroin was modified by UV-irradiation with the wavelength lambda = 254 nm. It was found that chitosan/silk fibroin blend surface is enriched in high surface energy component i.e. silk fibroin. The contact angle and the surface free energy were altered by UV-irradiation for both chitosan and chitosan/silk fibroin films. The surface roughness of chitosan, silk fibroin and chitosan/silk fibroin blended films was altered by UV-irradiation. UV-irradiation caused the decrease of surface roughness of chitosan films, silk fibroin films and films made of the mixture of chitosan and silk fibroin. (C) 2013 Elsevier B.V. All rights reserved.