PubMed | Brookhaven National Laboratory, Brazilian National Nanotechnology Laboratory and Brazilian Synchrotron Light Laboratory (LNLS)
Type: | Journal: Scientific reports | Year: 2015
Human hair has three main regions, the medulla, the cortex, and the cuticle. An existing model for the cortex suggests that the -keratin- based intermediate filaments (IFs) align with the hairs axis, but are orientationally disordered in-plane. We found that there is a new region in the cortex near the cuticles boundary in which the IFs are aligned with the hairs axis, but additionally, they are orientationally ordered in-plane due to the presence of the cuticle/hair boundary. Further into the cortex, the IF arrangement becomes disordered, eventually losing all in-plane orientation. We also find that in the cuticle, a key diffraction feature is absent, indicating the presence of the -keratin rather than that of the -keratin phase. This is direct structural evidence that the cuticle contains -keratin sheets. This work highlights the importance of using a sub-micron x-ray beam to unravel the structures of poorly ordered, multi-phase systems.