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Local structure of human hair spatially resolved by sub-micron X-ray beam.

Stanić V, Bettini J, Montoro FE, Stein A, Evans-Lutterodt K - Sci Rep (2015)

Bottom Line: We also find that in the cuticle, a key diffraction feature is absent, indicating the presence of the β-keratin rather than that of the α-keratin phase.This is direct structural evidence that the cuticle contains β-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.

View Article: PubMed Central - PubMed

Affiliation: Brazilian Synchrotron Light Source, CNPEM, SP 13083-970, Brazil.

ABSTRACT
Human hair has three main regions, the medulla, the cortex, and the cuticle. An existing model for the cortex suggests that the α-keratin- based intermediate filaments (IFs) align with the hair's axis, but are orientationally disordered in-plane. We found that there is a new region in the cortex near the cuticle's boundary in which the IFs are aligned with the hair's 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 β-keratin rather than that of the α-keratin phase. This is direct structural evidence that the cuticle contains β-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.

No MeSH data available.


Related in: MedlinePlus

Comparison of the wide angle x-ray scattering of cortex shown in (A) and cuticle shown in (B) measured with x -ray beam ⊥ to the hair’s axis. (C) showing the line projections of the integrated intensities for the peak 5.2 Å and the peak 4.6 Å of the two respective regions.
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f4: Comparison of the wide angle x-ray scattering of cortex shown in (A) and cuticle shown in (B) measured with x -ray beam ⊥ to the hair’s axis. (C) showing the line projections of the integrated intensities for the peak 5.2 Å and the peak 4.6 Å of the two respective regions.

Mentions: As shown in Fig. 4, wide angle x-ray scattering (WAXS) with the x- ray beam ⊥ to the hair axis, reveals structural information internal to the IFs. Three features are shown; a broad anisotropic 10 Å peak, a broad isotropic 4.6 Å ring, and a sharp arc at 5.2 Å. In Fig. 2A,D where the incident x-ray beam is to the hair’s axis, we can compare the 10 Å ring in the cuticle, and cortex. Clearly, the 10 Å feature is stronger in the cortex. The 10 Å ring reflects the correlations between keratin-coiled coils112122.


Local structure of human hair spatially resolved by sub-micron X-ray beam.

Stanić V, Bettini J, Montoro FE, Stein A, Evans-Lutterodt K - Sci Rep (2015)

Comparison of the wide angle x-ray scattering of cortex shown in (A) and cuticle shown in (B) measured with x -ray beam ⊥ to the hair’s axis. (C) showing the line projections of the integrated intensities for the peak 5.2 Å and the peak 4.6 Å of the two respective regions.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4663634&req=5

f4: Comparison of the wide angle x-ray scattering of cortex shown in (A) and cuticle shown in (B) measured with x -ray beam ⊥ to the hair’s axis. (C) showing the line projections of the integrated intensities for the peak 5.2 Å and the peak 4.6 Å of the two respective regions.
Mentions: As shown in Fig. 4, wide angle x-ray scattering (WAXS) with the x- ray beam ⊥ to the hair axis, reveals structural information internal to the IFs. Three features are shown; a broad anisotropic 10 Å peak, a broad isotropic 4.6 Å ring, and a sharp arc at 5.2 Å. In Fig. 2A,D where the incident x-ray beam is to the hair’s axis, we can compare the 10 Å ring in the cuticle, and cortex. Clearly, the 10 Å feature is stronger in the cortex. The 10 Å ring reflects the correlations between keratin-coiled coils112122.

Bottom Line: We also find that in the cuticle, a key diffraction feature is absent, indicating the presence of the β-keratin rather than that of the α-keratin phase.This is direct structural evidence that the cuticle contains β-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.

View Article: PubMed Central - PubMed

Affiliation: Brazilian Synchrotron Light Source, CNPEM, SP 13083-970, Brazil.

ABSTRACT
Human hair has three main regions, the medulla, the cortex, and the cuticle. An existing model for the cortex suggests that the α-keratin- based intermediate filaments (IFs) align with the hair's axis, but are orientationally disordered in-plane. We found that there is a new region in the cortex near the cuticle's boundary in which the IFs are aligned with the hair's 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 β-keratin rather than that of the α-keratin phase. This is direct structural evidence that the cuticle contains β-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.

No MeSH data available.


Related in: MedlinePlus