Development and characterization of silk fibroin thin films aiming biomedical applications

Silk fibroin (Bombyx mori) is a natural polymer that in recent years has been driving the development of new biomaterials. Nevertheless, few studies report the fabrication of fibroin films of large macroscopic dimensions applied in the treatment of cutaneous lesions. In this work, fibroin thin films with an area of 1033 cm2 were produced using the casting technique, aiming at the development of coverings for the treatment of skin lesions. It should be noted that in the literature there are no reports of the development of large fibroin films for the treatment of skin lesions caused by burns. For this purpose, thin layer chromatography equipment was adapted to produce fibroin thin films with large dimensions by two manufacturing methods. In the first method, fibroin was only degummed and solubilized in 98% formic acid, 5% m/m calcium chloride (CaCl2) with the addition of 40% m/m glycerol, while in the second method, fibroin was degummed, dissolved in CaCl2:C2H6O:H2O (1:2:8 M), dialyzed, lyophilized, solubilized in 98% formic acid and added 40% glycerol w/w. The SEM results showed that the degumming step did not degrade the protein and that the films had a regular surface (no bubbles), on the other hand, the addition of glycerol altered the fracture surface and made the films thicker (50 μm), highlighting the methods used to generate different surfaces. The FTIR analysis showed the presence of α-helix (amorphous phase) and β-sheet (crystalline domains) secondary structures. The XRD corroborated the results observed in the FTIR. The contact angle showed that the films have good wettability, being hydrophilic. TGA, DTG and DMTA showed that the films have high thermal and mechanical stability. Given the above, it is that it was possible to produce thin fibroin films with large macroscopic dimensions and thickness below 50 μm, transparent, flexible, hydrophilic, thermally and mechanically resistant by the casting technique. (AU)