The ability of extracted keratin proteins to self-assemble and polymerize into complex three
dimensional structures has led to their development as scaffolds for tissue engineering. Fabrication of
wool keratin scaffolds for long term cell cultivation was first reported by Tachibana et al. [44] in 2001.
The matrices were created by lyophilization of aqueous wool keratin solutions after controlled
freezing, which resulted in a rigid and heat-stable structure with a homogenously porous microarchitecture.
The keratins, which were shown to contain RGD and LDV cell adhesion sequences,
exhibited good cell compatibility and supported the attachment and proliferation of fibroblasts over a
long-term cultivation period of 23−43 days. In addition, the free cysteine residues present within the
scaffold were shown to be potential modification sites for the immobilization of bioactive substances
[44]. In later work, lysozyme was used as a model compound and linked to the keratin sponge via
disulfide and thioether bonds. Disulfide-linked lysozyme was gradually released over a 21-day period
whereas lysozyme linked via thioether bonds was stably maintained for up to two months. This work
demonstrated that the selection of a chemical crosslinker can uniquely determine the stability of an
immobilized bioactive substance on keratin sponges