Regenerated keratin fibers from chicken feathers for textile and biomedical applications

This dissertation focuses on dissolution of keratin from chicken feathers and subsequent development of normal and ultrafine fibers for textile and biomedical applications. In the last few decades, efforts have been made to transform the largely-available waste material, chicken feathers into fibers but they have yielded no success. In addition, keratin is preferred in biomedical applications due to the existence of cell-binding motifs in its molecular structures. However, 100% keratin ultrafine fibers have not been developed also due to lack of proper dissolution methods. Regarding the structures of scaffolds, three-dimensional (3D) fibrous structures possess advantages over two-dimensional (2D) structures as tissue engineering scaffolds since they show higher structural similarity to the natural extracellular matrices. In this research, dissolution conditions are studied in order to obtain keratin solution with good spinnability. First, keratin is extracted from chicken feathers with backbones preserved after cleavage of inter- and intramolecular disulfide bonds using cysteine. Sodium dodecyl sulfate (SDS) is applied to dissolve keratin for spinning and mechanism of dissolution of keratin with SDS is investigated. Normal keratin fibers are wet spun and 3D ultrafine keratin fibrous scaffolds are produced via electrospinning. Increasing SDS concentration intensifies ordered conformation of keratin and firstly increases and then decreases viscosity of solution, suggesting continuous disentanglement of keratin molecules and enhancement in inter- and intramolecular electrical repulsion. The diameters of obtained fibers as small as 20 microns also prove good drawability of keratin solution. The change of crystallinity is found to be consistent with that of tensile properties. In addition, structures composed of three-dimensionally oriented ultrafine pure keratin fibers are electrospun. The 3D scaffolds are water-stable. The adipose-derived mesenchymal stem cells penetrate more deeply and distribute more evenly in the 3D keratin fibrous structures comparing to commercial 3D scaffolds and electrospun 2D polylactic acid (PLA) scaffolds. The dissolution and 3D electrospinning methods are applied to wheat glutenin, another highly-crosslinked plant protein for adipose tissue engineering