Investigation of the damage on the outermost hair surface using ToF‐SIMS and XPS

Abstract

The outermost surface of the human hair is covered with a thin layer of fatty acids bonding proteins, which plays an important role in giving hair a soft and smooth feeling and surface hydrophobicity. In this study, changes in fatty acids and protein fragment ions were characterized using time-of-flight secondary ion mass spectrometry (ToF-SIMS) and X-ray photoelectron spectroscopy (XPS) to investigate hair damage. As a result, the intensity of the fragment ion m/z 76 related to cystine and cysteine, major components of hair keratin, decreased with the hair damage, which is consistent with generation of cysteic acid caused by oxidative cleavage of both thioester bond in the fatty acids and disulfide bond of cystine. Thus, it is indicated that hair damage can be evaluated by measuring m/z 76. Furthermore, 18-methyleicosanoic acid, the major component of the fatty acids, decreased rapidly in three bleaching processes, and the peak at m/z 76 also decreased correspondingly. These results suggest that the oxidative cleavage of thioester bonds in the fatty acids is the major change caused by the bleaching process.

Age‐dependent changes in damage processes of hair cuticle

“…Consequently, it was confirmed that the surface cuticles of the subjects elder than 40 are prone to be broken and this phenomenon is promoted by aging . It has been variously reported that reduction of 18‐MEA badly affects hair and that chemical treatments, such as bleaching, cause its drastic loss . In this study, it was revealed that aging also causes loss of 18‐MEA, especially in the age range elder than 40.…”

“…It has been variously reported that reduction of 18-MEA badly affects hair and that chemical treatments, such as bleaching, cause its drastic loss. 6,[11][12][13][14][15] In this study, it was revealed that aging also causes loss of 18-MEA, especially in the age range elder than 40. A number of significant changes in hair properties (diameter, density, luster, bending elasticity, lipids, minerals, etc.…”

“…The levels of the fatty acid 18-MEA on hair surface were measured by time-of-flight-secondary ion mass spectrometry (ToF-SIMS). 6 Measurements were performed at the root end (Point 0) and at a distance of 5 cm from the root end (Point 5) on each hair fiber. It was regarded that the point 0 represented the intact part and point 5 a segment weathered for approxi- mately 5 months.…”

Structural Analysis of the Outermost Hair Surface Using TOF-SIMS with C₆₀ Depth Profiling Technique

“…Figure 3 shows the TEM observation of cuticle cells and the depth profiling data of Cys/Cyc in the first cuticle layer. In the detection of the Cys/Cyc peak (m/z 76), it was confirmed that the overlapping of other peaks, such as C 6 H 4 , was small; thus the variation of peak intensity mainly reflected the change in Cys/Cyc composition [22]. It is indicated that a single layer of cuticle consists of sev- eral tissue layers, as a consequence of the peak intensity changes resulting from the difference in the Cys/Cyc composition of each tissue.…”

Nanoscale Molecular Characterisation of Hair Cuticles using Integrated AFM-IR

“…This is consistent with the stripping of the β-layer which commonly occurs in damaged hair. 20,21,[42][43][44] The partial splaying that occurs at the edge of the cuticle cell 45 , as well as external damage, as mentioned above with regard to the lipid β-layer, provided the opportunity to investigate the layering of the edge of the cuticle cell. Spectra across the edge, covering individual layers, showed significant changes to the amide, lipid and cystine-related regions.…”