Controlled assembly of secondary keratin structures for continuous and scalable production of tough fibers from chicken feathers

Tough keratin fibers from chicken feathers have been produced continuously via controlled assembly of secondary protein structures. Though research on utilization of keratinous wastes began decades ago, very few regenerated products with high quality were developed due to damage to the primary structures during extraction and poor recovery of the secondary structures in the regenerated materials. Fibers have the highest quality requirements among the regenerated keratin products, including high toughness and resistance to repeated laundering. Our group developed regenerated keratin fibers on a lab scale previously. However, the regenerated keratin had poor spinnability with low recovery of secondary protein structures. As a result, keratin fibers could not be produced continuously, and their properties, especially the wet strength, were not acceptable. In this paper, high drawing ratios of keratin fibers on a continuous line have been achieved via stepwise oxidation and drawing technology. This technology resulted in controlled assembly of disulfide crosslinkages, optimum recovery of the secondary structures, satisfactory mechanical properties and scalable production of keratin fibers. Furthermore, the use of inexpensive chemicals makes the continuous keratin fiber production developed in this work affordable for scale-up. The technology developed for continuous production of tough keratin fibers has high potential for the development of high quality regenerated products from other cysteine-containing protein materials.