Photochemical crosslinking of soluble wool keratins produces a mechanically stable biomaterial that supports cell adhesion and proliferation

• Published in: Journal of biomedical materials research. Part A Vol. 95A; no. 3; pp. 901 - 911
• Main Authors: Sando, Lillian, Kim, Misook, Colgrave, Michelle L., Ramshaw, John A. M., Werkmeister, Jerome A., Elvin, Christopher M.
• Format: Journal Article
• Language: English
• Published: Hoboken Wiley Subscription Services, Inc., A Wiley Company 01.12.2010; Wiley-Blackwell
• Subjects: adhesive; Amino Acid Sequence; Animals; Biocompatible Materials - chemistry; Biological and medical sciences; Biomaterials; Biomedical materials; Cell Adhesion - physiology; Cell Proliferation; Cross-Linking Reagents - chemistry; Crosslinking; Density; di-tyrosine; Elasticity; fibroblasts; Fibroblasts - cytology; Fibroblasts - physiology; keratin; Keratins; Keratins - chemistry; Keratins - genetics; Materials Testing; Medical sciences; Mice; NIH 3T3 Cells; photo-crosslinking; Photochemical; Photochemical Processes; Surgery (general aspects). Transplantations, organ and tissue grafts. Graft diseases; Surgical implants; Technology. Biomaterials. Equipments; Tensile Strength; Tissue Engineering - methods; Wool; Wool - chemistry; Cell proliferation; Tyrosine; Photochemical crosslinking; di-tyrosine; photo-crosslinking; Keratin; fibroblasts; Natural fiber; Cell adhesion; Animal fiber; Animal protein; Biomaterial; Wool; Adhesive; Fibroblast; Biomedical engineering
• ISSN: 1549-3296; 1552-4965; 1552-4965
• DOI: 10.1002/jbm.a.32913

Keratins extracted from various “hard tissues” such as wool, hair, and nails are increasingly being investigated as a source of abundant, biocompatible materials. In this study we explored a recent photochemical method to crosslink solubilized wool keratoses, with the aim of producing a mechanically favorable biomaterial. Wool proteins were isolated by oxidizing the disulfides and extracting the resulting soluble keratoses. The α‐ and γ‐keratose fractions were analyzed by liquid chromatography–mass spectrometry to identify their constituent proteins. Hydrogels were produced by covalent crosslinking of the α‐keratoses via a photo‐oxidative process catalyzed by blue light, a ruthenium complex, and persulfate. The presence of dityrosine crosslinks was demonstrated by high performance liquid chromatography and mass spectrometry analyses. The crosslinked α‐keratose material had moderate tensile strength and elasticity, and high adhesive strength. The material displayed modest shrinking after crosslinking, however the shrinking could be prevented by crosslinking in the presence of 2.5% glycerol, resulting in gels that did not shrink or swell. Small solutes such as Tris and glycerol influenced the crosslink density and elastic modulus of the crosslinked material. The α‐keratose was able to support adhesion and growth of NIH/3T3 fibroblasts in vitro. The fabrication of mechanically stable keratin biomaterials by this facile photo‐crosslinking method may be useful for various tissue engineering applications. © 2010 Wiley Periodicals, Inc. J Biomed Mater Res Part A, 2010.