Prospective ultramorphological characterization of human hair by optical coherence tomography.
OBJECTIVE
The continuous advancement in cosmetic science has led to an increasing demand for the development of non-invasive, reliable scientific techniques directed toward claim substantiation, which is of utmost relevance, to obtain data regarding the efficacy and safety of cosmetic products.


METHODS
In this work, we used the optical coherence tomography (OCT) technique to produce in vitro transversal section-images of human hair. We also compared the OCT signal before and after chemical treatment with an 18% w/w ammonium thioglycolate solution.


RESULTS
The mean diameter of the medulla was 29+/-7 microm and the hair diameter was 122+/-16 microm in our samples of standard Afro-ethnic hair. A three-dimensional (3D) image was constructed starting from 601 cross-sectional images (slices). Each slice was taken in steps of 6.0 microm at eight frames per second, and the entire 3D image was constructed in 60 s.


CONCLUSIONS
It was possible to identify, using the A-scan protocol, the principal structures: the cuticle, cortex and medulla. After chemical treatment, it was not possible to identify the main structures of hair fiber due to index matching promoted by deleterious action of the chemical agent.
Velasco
Maria Valéria Robles
MV
Laboratory of Cosmetology, Department of Pharmacy, School of Pharmaceutical Sciences, University of São Paulo, São Paulo, Brazil.
Baby
André Rolim
AR
Sarruf
Fernanda Daud
FD
Kaneko
Telma Mary
TM
Samad
Ricardo Elgul
RE
Vieira Júnior
Nilson Dias
ND
de Freitas
Anderson Zanardi
AZ
D044383:Black People; D006197:Hair / Q000187:drug effects* / Q000648:ultrastructure*; D006203:Hair Preparations / Q000494:pharmacology*; D006801:Humans; D021621:Imaging, Three-Dimensional / Q000295:instrumentation / Q000379:methods; D066298:In Vitro Techniques; D013864:Thioglycolates / Q000494:pharmacology; D041623:Tomography, Optical Coherence / Q000295:instrumentation / Q000379:methods*
D006203:Hair Preparations; D013864:Thioglycolates; C017487:2-mercaptoacetate