Hydration-responsive shape-memory keratin composite fibers and fabrication methods thereof
Hydration-responsive shape-memory keratin composite fibers are provided. These fibers have a keratin network structure formed by keratin α-helices bonded by disulfide bonds. Incorporated within the structure are cellulose nanocrystals (CNCs), which provide hydrogen bonds and stabilize the α-helix structure, introducing a hydration-responsive switch. Specifically, the CNCs are configured to arrange and connect the keratin α-helices, aligning their coil axis along the fiber axis.
1 . A method of fabricating a hydration-responsive shape-memory keratin composite fiber, comprising:
conducting a reduction reaction on a keratin source for extracting keratin molecules utilizing L-cysteine and urea;
mixing the extracted keratin molecules, cellulose nanocrystals (CNCs) and a reducing agent in an alkaline solution to obtain a homogenous keratin spinning dope;
extruding the keratin spinning dope through a needle by a pump to a coagulation bath to form as-spun fibers;
oxidizing the as-spun fibers to generate disulfide bonds between α-helix subunits to form keratin α-helices; and
crosslinking the keratin α-helices to form hydration-responsive shape-memory keratin composite fibers.
2 . The method of claim 1 , wherein the extruding is performed with an extrusion speed of 0.8-1 mL/h.
3 . The method of claim 1 , wherein the keratin source comprises wool, feathers, horns, hooves, mammalian hair, mammalian skin, mammalian nails and mammalian claws.
4 . The method of claim 1 , wherein the coagulation bath is a sodium dihydrogen phosphate aqueous solution.
5 . The method of claim 4 , wherein the coagulation bath has a pH less than 4.3 to facilitate keratin solidification and ion diffusion.
6 . The method of claim 1 , wherein the crosslinking is utilizing glutaraldehyde as a crosslinker.