Structure of photo-damaged white and naturally pigmented human hair.
J Photochem Photobiol B
; 202: 111673, 2020 Jan.
Article
in En
| MEDLINE
| ID: mdl-31786487
ABSTRACT
The effect of photo-degradation processes on the morphology and ultrastructure of pigmented and non-pigmented hair was evaluated in this work by small angle X-ray scattering (SAXS) and transmission electron microscopy (TEM). Samples consisted of three types of grey hair (separated out into subsamples of totally white and totally black strands) and one type of dark-brown hair exposed to solar irradiation for 75â¯h or to a mercury lamp for 600â¯h. SAXS patterns showed that irradiation mainly damaged the amorphous regions of hair, and in some types of hair, an ordered structure appeared, with spaces of ca. 4.5â¯nm. This structure occurred independently of the presence of pigments and its scattering intensity increased after irradiation. Layers of lipids present in the cuticle may be responsible for this scattering around 4.5â¯nm, as indicated by TEM images. TEM also showed morphological changes in the outermost cuticle layers, such as the degradation of endocuticle and the detachment of the cell membrane complex. Therefore, the results presented herewith showed that irradiation caused different damages to the hair amorphous fractions, especially in the cuticle layers, which are the most exposed areas of the hair strands.
Key words
Full text:
1
Collection:
01-internacional
Database:
MEDLINE
Main subject:
Sunlight
/
Pigmentation
/
Hair
Limits:
Humans
Language:
En
Journal:
J Photochem Photobiol B
Journal subject:
BIOLOGIA
Year:
2020
Document type:
Article