Cysteine-s-sulfonated keratin-based nanofibers – filtration and biomedical applications

Keratin is a fibrous protein that can be extracted from multiple sustainable resources (animal fibers, feathers, hair and horns) by sulfitolysis extraction in aqueous solutions. After extraction, the protein obtained as cysteine-S-sulfonated keratin (CSSK) is purified and freeze-dried so that it can be reprocessed to obtain innovative materials like films, sponges, hydro- or aerogels, and fibers (micro- or nanofibers). In particular, CNR STIIMA Biella carries out research that is strongly related to local industries like the manufacturing of textile materials from synthetic and natural fibers (i.e., wool and cashmere) and the recycling of wool fibers from sheep farming which are only focused on production of milk and meat. For this reason, CNR STIIMA Biella constantly studies the extraction of CSSK from animal fibers and works in the valorization of this biopolymer. As a result, CNR STIIMA Biella has extensively worked on the production of CSSK-nanofibers for filtration and biomedical applications by electrospinning. So far, CSSK-nanofibers have been obtained using pure CSSK solutions or in blends with synthetic/natural polymers in aqueous solutions or organic solvents. Therefore, this work will present the processing of this biodegradable biopolymer to produce CSSK-based nanofibers discussing their properties and functionalization methods for filtration and biomedical applications.