Electrospun silk fibroin using aqueous and formic acid solutions

Silk fibroin is a polymer of interest thanks to its ability to be transformed into different structures, such as fibers. The electrospun technique can produce micro and nanofibers, presenting advantages like high superficial area and porosity. However, this polymer needs to be dissolved into a liquid solution using solvents. This study evaluates the effect of formic acid and water as solvents on the silk fibroin electrospun fibers morphology, chemical structure, and thermal properties. In this case, silk fibroin was obtained from silk fibrous wastes. The results suggest that the morphology obtained from both solutions has a similar fiber diameter. Electrospun silk fibers using formic acid solution present a relatively high porosity and recrystallization enthalpy. In contrast, the percentage of crystallinity and degradation temperature were higher in samples with aqueous solution. This indicates that the aqueous process allows higher structural ordering, improving the thermal stability for the fibers. Graphical abstract: [Figure not available: see fulltext.]