Keratins and lipids in ethnic hair

Human hair has an important and undeniable relevance in society due to its important role in visual appearance and social communication. Hair is mainly composed of structural proteins, mainly keratin and keratin associated proteins and lipids. Herein, we report a comprehensive study of the content and distribution of the lipids among ethnic hair, African, Asian and Caucasian hair. More interestingly, we also report the study of the interaction between those two main components of hair, specifically, the influence of the hair internal lipids in the structure of the hair keratin. This was achieved by the use of a complete set of analytical tools, such as thin layer chromatography‐flame ionization detector, X‐ray analysis, molecular dynamics simulation and confocal microscopy. The experimental results indicated different amounts of lipids on ethnic hair compositions and higher percentage of hair internal lipids in African hair. In this type of hair, the axial diffraction of keratin was not observed in X‐ray analysis, but after hair lipids removal, the keratin returned to its typical packing arrangement. In molecular dynamic simulation, lipids were shown to intercalate dimers of keratin, changing its structure. From those results, we assume that keratin structure may be influenced by higher concentration of lipids in African hair.     

Grey hair: clinical investigation into changes in hair fibres with loss of pigmentation in a photoprotected population

Loss of pigmentation in hair fibres is one of the most obvious phenotypic changes with ageing and has been a topic of increasing interest in the study of follicle biology. The onset of greying brings cosmetic complaints that grey fibres are wild or difficult to manage. Of course, these perceptions may be the consequence of visual obviousness rather than underlying physical or chemical differences. Although several studies have compared pigmented and unpigmented fibres, few have tried to control genetic and ethnic difference as well as extrinsic factors such as photoexposure and chemical treatment. We have recruited subjects with salt-and-pepper hair from a population of Old Order Mennonites who, for cultural reasons, are not only prohibited from chemically treating their hair but also limit their exposure to sunlight. Hair samples were examined for elemental composition, surface energy, Young's modulus, break stress, bending modulus, shear modulus and water sorption/desorption isotherm. The parameters were evaluated statistically for global differences, individual differences and typical individual differences. Consistent with previous published literature, few global differences were found between pigmented and unpigmented hair across the population. We do find that many individual subjects had differences between pigmented and unpigmented fibres. These differences tend to be more pronounced in bulk than in surface properties. The small differences in mechanical properties and moisture uptake and loss lend support to the perception by consumers that grey hair is wilder, drier and less manageable.     

Dyeing behaviours of amino heterocyclic compounds as blue oxidative hair dye precursors applied to keratin fibres

Several novel heterocyclic compounds based on 1,2,3,4-tetrahydroquinoline and 2,3-dihydroindole have been investigated for their application of colour keratin fibres as blue oxidative dye precursors, especially to human hair. The colourants we studied contained anyone of these dyes (concentration range from 0.005% to 6%), and some common oxidative hair dyes, such as p-phenylenediamine, toluene-2,5-diamine sulphate. Experiments were carried out on the method of mixing hair colourants with H(2)O(2) gel at the ratio of 1 : 1, accompanied by pH = 8～11. It is demonstrated that 1,2,3,4-tetrahydroquinoline derivatives could be considered as an excellent candidate for blue dyes, and N-methyl-7-amino-1,2,3,4-tetrahydroquinoline is the most outstanding one among this kind of compounds. They own significant advantages of colour purity, stability and fastness. On the other hand, 2,3-dihydroindoles show the similar colours but not stable and brilliant enough.     

不同处理对猪毛角蛋白提取效果及功能特性的影响

目的 探究不同处理方式对猪毛角蛋白提取效果及功能特性的影响。方法 采取碱解法、酶解法、蒸汽爆破法、还原法4种处理提取猪毛角蛋白,研究不同处理对猪毛溶解率和可溶性蛋白含量以及角蛋白功能特性的影响。结果 碱解和蒸汽爆破处理下猪毛溶解率较高,均为65%左右,而还原法处理的可溶性蛋白含量较高,为165mg/g左右;不同处理对猪毛角蛋白的功能特性影响差异较大,溶解性和持水性较好的分别是碱解和蒸汽爆破处理得到的角蛋白,而还原法提取出的猪毛角蛋白持油性、冻融稳定性、乳化性及乳化稳定性较好。结论 各处理方法均有利弊,需要根据角蛋白的用途选择合适的提取方法。本研究为猪毛角蛋白的提取及猪毛的充分利用提供了一定理论参考。     

Investigating the relationship between the hair fiber proteome and hair quality

Many hair characteristics (e.g. color and curl) are genetically determined. Here, we investigated whether hair quality is also genetically controlled and related to differences in hair composition. Female, Caucasian subjects ( n  = 292) were recruited into this study and segmented by self-perceived hair quality and by permanent colorant usage. Hair fibers were collected and characterized by amino acid analysis, dry tensile elastic modulus testing and two-dimensional electrophoresis of hair protein extracts.
Protein analysis revealed a string of 66 kDa proteins that correlated with hair of high quality. Loss of low molecular weight (14–29 kDa) proteins increased with colorant usage, particularly in hair of low quality. Amino acid analysis showed that the levels of serine and threonine across all the subjects followed bimodal frequency distributions suggestive of a genetic influence. Overall, data suggested that perception of quality was linked to high serine and threonine levels. In addition, where hair was colored, quality was associated with lower cysteic acid levels. Lower cysteic acid levels were not linked to lower colorant usage and our data suggest that high quality hair may be more resistant to colorant damage. Elastic modulus was significantly higher in hair of higher quality (4.65 GPa) compared to all medium and low quality hair combined (4.3 GPa), P  < 0.02. This suggests a link between altered hair composition and mechanical properties. In conclusion, the composition and mechanical properties of hair have been linked to hair quality. We hypothesize that hair quality is thus likely to be genetically determined. Understanding of the links between hair composition and its properties could be utilized in the future for designing products targeted to each individual's hair make-up, and for producing diagnostic tools for determining hair quality.     

基于漆酶催化角蛋白头发纤维生物修复染色

针对目前常规染发过程中氧化剂及染发剂对角蛋白头发纤维的损伤及易对人产生过敏等问题,采用漆酶催化盐酸多巴胺聚合生色并对角蛋白头发纤维进行原位染色,以达到生态安全、环保健康、生物修复、染色牢固的角蛋白头发纤维染黑效果。借助测色配色仪、万能材料试验机、扫描电子显微镜、傅里叶变换红外光谱仪和纺织品防紫外性能测试仪等对染色角蛋白头发纤维的结构和性能进行了表征。结果表明：原位染色角蛋白头发纤维表面色深值为23.9,表观颜色色相为黑色,防紫外线性能也得到提高,紫外线防护系数为100⁺,染色后角蛋白头发纤维断裂强力提高7.8%;漆酶催化盐酸多巴胺聚合生成聚多巴胺色素,且附着于角蛋白头发纤维表面,与角蛋白头发纤维结合牢固,染色角蛋白头发纤维的干、湿摩擦色牢度及耐洗变色牢度分别达到4级、3～4级及4～5级。     

Temperature as a moisture cue in haptics on hair

A mechanism for giving a moisturized or dried‐out feeling to hair was investigated. A two‐step approach was conducted in order to elucidate the issue. First, we have reviewed previous studies that are related to the sensory perception of materials not only in cosmetic industry but also in other fields, such as textile and architecture industries, and established a hypothesis. Second, we have verified the hypothesis derived from the first step and identified the mechanism for the moisturized or dried‐out feeling that people feel by measuring the heat transfer characteristic, q_max. The results revealed that the moisturized or dried‐out feeling that people feel at the moment of contact with hair was highly related to the temperature drop at the skin surface. The results also revealed that the moisturized or dried‐out feeling strongly depends on the hair shape (meandering and diameter), surface damage and the water content of hair fibres which constitute the hair swatch. The moisturized feeling, however, was not related to the water content of hair fibres at a constant relative humidity (RH), as the differences in the water content of the hair fibres at a constant RH were too small for the recognition of the difference in the moisturized feeling.     

Influence of microemulsion structure on cystine reactivity with keratin fibres

The activity of thioglycolic acid, incorporated in a microemulsion, towards cystine residues present in keratin proteins has been investigated.
In an attempt to relate the structural state of the microemulsions to cystine reactivity, an appropriate model system showing a large microemulsion domain with diverse structures was chosen.
The realm of preferentially hydrocarbon-continuous microemulsion-type media was found to induce the highest activity.     

Keratin-based peptide: biological evaluation and strengthening properties on relaxed hair

A peptide based on a fragment of hair keratin type II cuticular protein, keratin peptide (KP), was studied as a possible strengthening agent for weakened relaxed hair. The peptide was prepared both in aqueous water formulation (WF) and organic solvent formulations (OF), to determine the effect of organic solvents on peptide interaction with hair and the differences in hair recovery. Both peptide formulations were shown to improve mechanical and thermal properties of weakened hair with peptide in OF showing the stronger effect. As a potential new hair care product, and so would necessitate contact with skin, the cytotoxicity and genotoxicity of the peptide were also evaluated through different methodologies (Alamar Blue assay, 2'-7'-dichlorofluorescein probe, cell morphology and growth and evaluation of DNA damage by an alkaline version of the comet assay) in skin fibroblasts. These tests are indicators of the potential of peptide to cause irritation on skin or to be carcinogenic, respectively. The peptide in WF did not cause cytotoxicity or genotoxicity in any of the concentrations tested. The presence of OF, however, induced a 20% decrease in cell viability in all of the range of concentrations used after 72-h incubation. Moreover, OF inhibited cell growth and was considered genotoxic at first contact with cells. The peptide was therefore considered a promising strengthening agent for hair and was shown to be innocuous when applied in WF.     

The location of the thioglycolic acid molecules in intrafibrillar unordered areas of the human hair keratin structure

It has been established after conducting an X-ray diffraction study of the structure of hair treated with the thioglycolic acid solution that the preferable location of thioglycolic acid molecules should be the intrafibrillar unordered areas. Based on this fact it has been concluded that the redistribution of disulphide bonds of hair occurs mainly in the mentioned above areas when treated with thioglycolic acid solution.     

The structural implications of water hardness metal uptake by human hair

Human hair can extract significant levels of calcium and magnesium, water hardness metals, from tap water immediately following chemical treatments and during hygiene practices. We have previously shown that this uptake is primarily a function of the condition of the hair. Depending on the extent of chemical damage, the hair can extract notable amounts of water hardness metals even from soft water. As water hardness metals concentrate primarily in the cuticle layers of the hair fibre, it is hypothesized that their presence will affect the structural properties that are chiefly driven by the cuticle. We examined hair mechanics and styling by technical measures of single-fibre torsional and tensile properties, combability and style retention as a function of the calcium and magnesium content of virgin and bleached hair. Our work has indicated that water hardness can affect hair properties. Fibre stiffening was induced by the presence of water hardness metals inside the fibres of both virgin and bleached hair. A reduction in combing forces was also observed, and this effect is believed to be a result of the stiffening. The style retention of virgin hair was improved by water hardness metals, whereas that of bleached hair was slightly reduced.     

Studies of factors affecting light scattering by individual human hair fibres

An automated goniophotometer has been built to investigate the scattering of light by different types of singly mounted human hair fibres using white light and laser illumination. The effects that varying hair colour and treatment (gold coating, ultraviolet irradiation and dyeing) have on the specular reflectance and on the half-peak-height width (ω) have been studied. The polarization of light has been used to discriminate between light reflected from the front surface and light scattered internally by the hair. It has been found that the analysis of results from individual hair fibres has been useful in understanding the light scattering mechanisms which occur in human hair.