ToF‐SIMS characterization of the lipid layer on the hair surface. I: the damage caused by chemical treatments and UV radiation

Abstract

In this study, we investigated how the lipids bound to the outermost surface of human hair are affected by chemical treatments such as hair bleach and ultraviolet (UV) radiation using time-of-flight secondary ion mass spectrometry (ToF-SIMS). Many lipid components are bound covalently via a thioester or ester linkage on the outermost surface of hair. We studied how these components are changed by chemical treatment. It was found that the fatty acids covalently bound via a thioester linkage are removed more easily than those with an ester linkage. Eighty percent of the 18-MEA (18-methyleicosanoic acid), which is a major component of lipids, was removed in a single bleach treatment, and most had vanished entirely after three treatments. We also investigated the influence of UV radiation and found that the amount of 18-MEA decreased with the radiation time. More than 90% of the 18-MEA was removed by UV radiation with corresponding exposure of three summer months. Copyright

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.…”

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

“…The 18‐MEA existing on the hair surface is detected as the negative molecular ion peak at m / z 341, the molecular ion peak of 18‐MEA . The oxidative cleavage of thioester bonds was evaluated by monitoring the change in the peak m / z 341 intensity . Figure shows the dependence of the decrease of the peaks at m / z 341 and m / z 76.…”

“…The surface damage of hair leads to changes in the physical properties such as increase in hydrophilicity and friction, which decreases hair quality. In previous studies it was revealed that serious damage leading to cleavage of disulfide bonds in cystine and decreasing of the fatty acids occur on the hair surface as shown in Fig. .…”

Effect of Oxidation Stress on the Mechanical Property of Human Hair

“…Even if the hair originally includes much melanin, the damages by UV exposure might be promoted by colouring and bleaching treatment, because of remaining agents and denaturation of hair itself [3]. It is also reported that more than 90% of the 18-MEA was removed by UV radiation with corresponding exposure for three summer months [4]. By elucidating the mechanism of oxidative damage by chemicals and UV, a guideline to prevent the hair damage would be clarified.…”