Structure-property relationships of meta-kerateine biomaterials derived from human hair

The structure-property relationships of kerateine materials were studied by separating crude hair extracts into two protein sub-fractions, referred to as alpha- and gamma-kerateines, followed by their de novo recombination into meta-kerateine hydrogels, sponges and films. The kerateine fractions were characterized using electrophoresis and mass spectrometry, which revealed that the alpha-fraction contained complexes of type I and type II keratins and that the gamma-fraction was primarily protein fragments of the alpha-fraction along with three proteins of the KAP-1 family. Meta-kerateine materials with increased amounts of gamma-kerateines showed diminished physical, mechanical and biological characteristics. Most notably, materials with higher gamma-content formed less elastic and less solid-like hydrogels and sponges that were less hydrolytically stable. In addition, a model biological assay showed that meta-kerateine films with greater amounts of gamma-kerateines were less supportive of hepatocyte attachment. Investigation into the mechanism of attachment revealed that hepatocyte adhesion to meta-kerateines is not mediated by the pi integrin subunit, despite the presence of LDV binding motifs within the type I alpha-keratins. This work to define the role of protein composition on biomaterial function is essential for the optimization of keratin biomaterials for biomedical applications. (C) 2011 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.