A highly resistant structure between the cuticle and the cortex of human hair. II . CARB , a penetration barrier

ObjectiveTo investigate the effects of different molecular weight (MW), wool derived hydrolysed keratins (i.e. peptides) on the physical properties of relaxed textured hair.MethodsVery curly hair of African origin was relaxed using sodium hydroxide‐based treatment. Relaxed hair was treated with different MW peptides derived from keratin protein and an amino acid, L‐Leucine. The low‐MW keratin peptides were 221 Da, the mid‐MW keratin peptides were approximately 2577 Da, and the high‐MW keratin peptides were approximately 75 440 Da. The penetration of these different peptides into relaxed hair was evaluated using a laser scanning micrometre and by fluorescence microscopy. The effect of these compounds on single‐fibre mechanical properties and thermal properties was evaluated using tensile and DSC testing, respectively.ResultsLow‐ and mid‐MW compounds were able to penetrate deep into the hair cortex. High‐MW peptide adsorbed onto the hair surface and possibly slightly penetrated into the outer layers of the fibre surface. Both mid‐ and high‐MW keratin peptides, increased Young’s modulus and reduced hair breakage at 20% and 80% relative humidity. With the exception of mid‐MW peptide, other peptides and amino acid were not able to modify thermal properties of relaxed textured hair.ConclusionsOur data suggest that low‐MW compounds may increase hair volume, and high‐MW peptides may repair damage on freshly relaxed textured hair.

Section: Discussionmentioning

confidence: 99%

Penetration of different molecular weight hydrolysed keratins into hair fibres and their effects on the physical properties of textured hair

Malinauskytė

Shrestha

Cornwell

et al. 2020

“…Only in Cu1, an unstained structure (marked by an *) is seen beneath the endocuticle. This is the structure CARB, which was previously proposed to be a penetration barrier [10].…”

Section: Resultsmentioning

confidence: 99%

“…The penetration of direct dyes into hair fibres is inhibited at the interface between the cuticle and the cortex [16]. We previously reported that the barrier is thought to be the CARB, which is located beneath the endocuticle of the innermost cuticle cell layers [10]. In this study, at which developing stage the barrier ability against dye penetration is generated was investigated.…”

Section: Resultsmentioning

confidence: 99%

“…Our previous studies [9–11] found that (1) there is a chemically resistant structure at the interface of the cuticle and the cortex; (2) that structure plays a role as a barrier against the penetration of direct dyes; (3) steryl glycoside lipids containing N‐acetylglucosamine are present at the interface of the cuticle and the cortex and these lipids were also detected in the follicle [12]; and (4) a thin amorphous‐shaped structure is present between the endocuticle of the innermost cuticle and the cell membrane complex (cmc) located between the cuticle and the cortex. That structure is thought to be the chemically resistant structure in question and to contain the glycolipid.…”

Section: Introductionmentioning

confidence: 99%

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A highly resistant structure between the cuticle and the cortex of human hair III: Characterzation of the structure CARB

Takahashi

2021

Self Cite

Objective It was previously reported that a highly resistant structure, which functions as a barrier against the penetration of dyes, is present at the interface between the cuticle and the cortex of human hair. That structure was named CARB, cuticle anchored resistant base. The goal of this study was to clarify the formation and composition of the structure CARB. Methods Cuticular substructures were observed from the keratinized area of each hair to its root end. The positions where the CARB structure appeared were isolated, and the barrier ability before and after that structure was evaluated. The distributions of glycolipid and cystine were measured using a nano‐IR and a transmission electron microscope (TEM). Results Cuticular substructures were fully constructed several mm from the hair bulb of the hairs observed. The results show that keratinization at the distal side of the cuticle cell precedes that of the proximal side, and CARB is fully constructed last among the substructures. Glycolipid was preferentially distributed at CARB in the keratinized area. The cystine content of CARB is lower than that of the A‐layer; however, it is slightly higher than that of the exocuticle and the inner layer. Conclusion These results demonstrate that CARB is produced in the final stage of keratinization of the cuticle layers. The rich contents of glycolipid and cystine might contribute to its resistant property.

“…Generally, the external protective layer of the hair fibre is covered by hair scales, which aggravate the penetration of tannins and metal salts [6]. Recent investigations of human hair fibres demonstrate that a highly resistant structure named, cuticle anchored resistant base (CARB), between the cuticle and the cortex serves as a penetration barrier [7]. To facilitate the fixation and penetration of vegetable dyes, different pre‐treatments of the hair tresses are necessary.…”

Section: Introductionmentioning

confidence: 99%

Investigations of vegetable tannins as hair dyes and their interactions with pre‐bleached hair fibres

Sargsyan

Vill

Hippe

2020

The aim of this work was to investigate an alternative hair-dyeing method with vegetable colourants as the tannins, as well as the impact of pre-treatment as the bleaching process. METHODS: Untreated, 1, 2 and 3 times bleached hair tresses that were dyed with tannins in combination with metal salts were characterized. The wash fastness and the colour strength of the vegetable-dyed hair tresses were spectrophotometrically investigated. RESULTS: To determine the colour strength KS and the wash fastness of vegetable-dyed and pre-bleached hair tresses, a three-dimensional colour coordinate system-CIELabwhich describes the visual spectra is used. The distance between two colours in the CIE-Lab colour space is expressed by DEvalues , which are used to identify the wash fastness of the vegetable dye. The hair tresses that had been 3 times pre-bleached showed the highest colour strength and the best wash fastness. The fixation of the tannin-mordant complexes on the hair fibre proceeded effectively just when the hair tresses were bleached before the dying process. It is suggested that the sulphonic acid groups, which increase after bleaching hair, interact with the tannin-mordant hair dye and lead to stronger cross-links between keratinous fibres and tannin-mordant complexes. It was observed that the colour strength of the vegetabledyed tresses correlates with the bleaching process. CONCLUSION: The presented results demonstrate that the fixation of the vegetable tannin-mordant dying solution on the hair fibres succeed effectively on pre-bleached hair tresses. a une plus forte cohesion entre les fibres k eratiniques et les complexes tanin-mordant. Une corr elation entre l´intensit e de couleur des m eches color ees par les pigments v eg etaux et le degr e de d ecoloration a puêtre observ ee. CONCLUSION: les r esultats pr esent es dans cette etude d emontrent que la fixation du pigment vegetal tanin-mordant en solution est possible et efficace sur des m eches de cheveux d ecolor ees au pr ealable.