Differences in regenerated silk fibroin prepared with different solvent systems: From structures to conformational changes

Dissolution is an important part of silk fibroin (SF) reprocessing, and it is the only way to process it into films, gels, porous scaffold materials, and electrostatic spinning silk fibers. There are a variety of dissolution systems used to dissolve SF. However, few studies have focused on the differences between these different solvent systems. The dissolution of SF with different solvent systems was investigated in this study. Regenerated silk fibroin (RSF) solutions and films were characterized by dynamic light scattering, Fourier transform infrared spectroscopy, differential scanning calorimetry, X-ray diffraction, and scanning electron microscopy. The results show that the RSF film structures changed with the solvent system, especially LiBr-H2O. The characterization proved that the random coil did not change into a -sheet structure during film formation, and this indicated that its crystal structure and thermal stability was different from others. Interestingly, the differences in the morphologies of all of the RSF films prepared with different solvents were outstanding. Because the mechanism and force of the ion in the solvent systems were different, the SF molecule was hydrolyzed differently in individual solvent systems and produced different hydrolyzed SF molecular chains. These chains had different self-assembly processes and would lead to RSF products with different microstructures and properties. This suggests that a suitable solvent should be chosen for different uses. (c) 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 41959.