Contributions to the chemistry of human hair: II. Lipid chemical aspects of permanently waved hair

The cell membrane complex (CMC) and the internal lipids of untreated and permanent waved hair were investigated. The permanent waving procedure results in a lower amount of the cell membrane fraction that could be isolated compared to untreated hair. There is no difference in the amino acid composition of the CMC fractions. The internal hair lipids were extracted from the CMC fraction with chloroform/methanol. For untreated human hair the cell membrane complex yields 57% of lipid material, whereas from the CMC of permanent wave hair only 35% of lipids could be extracted. The polar lipids and the fatty acids are the main components of the internal hair lipids. After a permanent waving treatment there is a distinct decrease in the polar lipid fraction which is higher at alkaline (pH 9) than at neutral pH (pH 7). The reduction treatment at pH 9.0 also causes a cleavage of the fatty acid fraction in the internal hair lipids.     

Evolution in the composition of human skin surface lipids during their accumulation on scalp and hair

Qualitative examination of human surface lipids collected using a surfactant solution shows that there are no significant differences between individuals when the samples are collected after one day, starting from clean hair and scalp. On the contrary, samples collected after 4 days reveal discrepancies within the population, related to the oily hair symptom.
An evolution in the composition of the recovered mixture occurs during the 1–4 days accumulation period, which mainly results in an increased unsaturation of the total (free + glycerides) fatty acids fraction isolated after saponification.
A two-step mechanism is proposed to account for the observed evolution: in a first step, free fatty acids are cleaved from glycerides by the well known enzymatic hydrolysis. Analytical determinations show that this process is structure dependant, the straight chain saturated acids being more readily hydrolyzable than the unsaturated and branched chain species. In a second step, free fatty acids are immobilized on the keratinic fibers, by a process which involves the formation of Ca salts.
This evolution results in a decreased viscosity of the skin surface lipids and in an increase of the low temperature melting fraction of the mixture. Its extent is more or less pronounced, depending upon the individuals. Subjects who exhibit extensive evolution are affected by the oily hair symptom.
Evolution de la composition des lipides superficiels humains durant leur accumulation sur le scalp et les cheveux     

Profiling lipids across Caucasian and Afro-American hair transverse cuts, using synchrotron infrared microspectrometry

Synchrotron-based infrared microscopic measurements have been performed on various hair transverse sections, sampled either from the heads of Caucasian or Afro-American subjects. Lipid content of various virgin hair transverse sections was established, with an unprecedented resolution. The variations in shape and intensity of the CH(2), CH(3), amide I and amide II bands, before and after lipid removal by solvent extraction, were profiled, showing clearly that Caucasian hair often contains lipids localized inside the medulla and to a lesser extent inside the cuticle. This statement does not hold for the Afro-American hair analysed. For this, the FT-IR spectra do not change within the hair section and are insensitive to solvent extraction. The importance of the origin of hair on its physical and chemical properties has to be taken into account in future investigations.     

Contributions to the chemistry of human hair. 1. Analyses of cystine, cysteine and cystine oxides in untreated human hair

Amino acid analysis, photometry and polarography were selected as analytical methods for the determination of thiol and disulphide groups in untreated human hair and the results are discussed. The pre-treatments necessary for the different analytical methods, e.g., hydrolysis, to some extent already induce chemical changes of the cysteine and cystine derivatives leading to method-dependent differences in the results. In many cases the partial oxidation products of cystine are supposed to be responsible for this effect. Electron Spectroscopy for Chemical Analysis (ESCA), as an analytical method for the determination of the cystine oxides, was found to be inapplicable due to insufficient resolution and sensitivity, whereas by the use of Fourier Transform Infrared (FTIR) Spectroscopy the sulphur-oxygen vibrations could be analysed and cystine monoxide and cystine dioxide were detected.     

拉伸改性处理毛发纤维的氨基酸含量分析

通过毛发拉伸改性前后的氨基酸全分析，研究了拉伸改性处理过程对毛发结构和性能的影响，进而探讨了毛发拉伸改性的机理。     

Fine details on the surface of human hair

Some previously unreported fine variations in the form of normal hairs are described as they are observed in the scanning electron microscope (SEM). They all arise in the course of surface frictional wear and the chipping away of the hair surface scale edges and include remanent surface impressions of cuticle scale edges, 'false' scale edges, granular surface remnants and highly irregular (chevron) scale patterns. Mechanisms are proposed for the way in which each of these different fine features arise.
The paper also contains deliberations on the conditions for operating the SEM consistent with obtaining the best information about the architecture of hair surfaces. The correctness of viewing orientation of scanning electron micrographs is also emphasized to avoid misinterpretation of features on the hair surface.     

有色动物纤维脱色保护剂在黑色人发漂白中的应用

黑色人发漂白的难点在于获得较高白度的同时保留原有人发的品质,常规的氧化还原漂白可赋予人发一定的白度,但使其手感干枯毛糙、无光泽.将纤维保护剂WBH应用于黑色人发的漂白工艺中,通过单因素试验得出纤维保护剂WBH、30%双氧水及柔软剂SILYOUSOFT T8182的最佳用量:漂白工艺中,30%双氧水的最佳用量为120%(omf),纤维保护剂WBH在Fe2+预媒处理和氧化漂白中的最佳用量分别为6%、8%(omf),SILYOUSOFT T8182在还原漂白中的最佳用量为8%(omf).扫描电镜照片也证实,纤维保护剂WBH对黑色人发起到保护作用.     

拉伸改性处理毛发纤维的红外光谱研究

通过毛发拉伸改性前后的红外光谱分析，研究了拉伸改性处理过程对毛发纤维结构的影响，进而探讨了毛发拉伸改性的机理。     

The non-linear viscoelastic behaviour of human hair at moderate extensions

We report the results of experiments carried out on the stress relaxation of slightly stretched human hair. The results show that human hair is viscoelastic, and that when quickly extended to a moderate degree (0.5-6.5%) and held, the force generated will fall to half its original value in about 15 h. However, the relaxation process is also dependent on extension, so that iso-chronous (constant time) data is non-Hookean. We show that the iso-chronous stress/strain behaviour departs from linearity at about 1% extension and the modulus progressively decreases thereafter according to a power-law relationship with strain.     

Resistance of human hair cuticle after a shaking process in wet conditions: comparison between Chinese and Caucasian hair

Hair cuticle is the first protection shield of hair against external aggressions such as daily combing or brushing that induce friction, mechanical stress leading to ageing process. The identification of alterations of the hair surface induced by shaking process of various hair fibres, such as virgin and chemically treated Chinese and Caucasian hair, sheds some light on some specific features, e.g. Chinese cuticle is torn out in smaller particles than Caucasian, which seems to be related to geometrical rather than ethnic reasons. The present work also shows that two geometrical parameters of human hair, the inter‐scale distance and the scale angle are directly linked to fibre dimensions, regardless of ethnic origin. Representative of hair with an average larger cross‐sectional area, Chinese hair shows a slightly smaller inter‐scale distance as well as a higher scale angle. On the other hand, Chinese hair cuticle seems to be more sensitive to chemical treatment than Caucasian hair, at least for straightening treatment taken here as an example. Such an approach can be of interest in designing cosmetic products more suited to specific needs of human hair.     

Contributions to the chemistry of human hair: III. Protein chemical aspects of permanent waving treatments

The influence of permanent waving on hair proteins was studied in order to obtain additional information about the chemistry of this cosmetic treatment. It was shown by amino acid analysis that with increasing reduction time during treatment fewer disulphide bonds were reformed in hair during subsequent reoxidation. Simultaneously, an increasing amount of sulphur-containing material is liberated from the hair, as demonstrated by the sulphur balance calculated from the sulphur-containing amino acids. The amount liberated is increased when an extensive soaking of the samples in water between the reduction and reoxidation step is performed. Comparing treatments with the use of reducing solutions of pH values between 7.5 and 10.0, it was found that the largest amount of cystine cleavage occurs at pH 9.0. All hair samples reduced at pH values above pH 8.5 showed incomplete reformation of the disulphide bonds during subsequent reoxidation. This was indicated by the content of free SH-groups and cysteic acid, as quantified by amino acid analysis. The damage to the hair proteins due to permanent waving was further confirmed by the determination of the pronase solubility. The reductive treatment of hair at pH 7.5 led to a relatively low degree of reduction, however all sulphur bonds were reformed during subsequent reoxidation.     

The mutagenicity and carcinogenicity of hair dyes

A number of the constituents of semi-permanent and permanent hair dyes have been shown to be mutagenic in bacteria, to induce mutation, chromosome breakage, sister chromatid exchanges and malignant transformation in mammalian cells, to cause mutation in Drosophila , to induce mitotic recombination in yeast and to induce tumours in rodents. Some hair dye ingredients and commercial dyes have been shown to give rise, in the urine of treated rats, to metabolites which are also mutagenic in bacteria.
The test systems used are briefly described and the data generated are reviewed. In addition, attempts to identify whether the hazards predicted from the laboratory studies present a risk to man either by epidemiological studies or monitoring of exposed populations are also discussed.
La mutagenese et la carcinogenese des colorants capillaires     

Studies on the cosmetic criteria of the hair after shampoo

An objectivised sensorial method for evaluating the effects of shampoos on the appearance and manageability of the hair is described. Two different shampoos for greasy hair were applied twice weekly for a period of 4 weeks to the right and left sides (split-head tests) of six subjects having greasy hair, the same shampoo being applied to the same side. A trained observer used a continuous rating scale to assess nine cosmetic parameters; overall assessments by observer and subjects were noted. Evaluations were made immediately after and at various intervals following shampoo. The data were presented in ‘profile graphs’ and evaluated statistically. Shampoo A was found to be significantly better (P < 0.05) than shampoo B for all parameters immediately after shampoo and for six parameters after 1 day. The differences between A and B were no longer significant after 2 days, and only marginal differences were noted after 3 and 4 days. Analysis of the results of forty additional split-head tests carried out with ten different shampoos revealed interdependence (P < 0.01) between some parameters. Our results show the elective action of shampoos on the cosmetic parameters, the duration and limits of this action, and the interdependence between certain parameters. Etudes sur les critères cosmétiques de la chevelure après shampooing     

拉伸-定形处理对人发强伸性能的影响

人发及羊毛等角蛋白纤维经拉伸一定形处理后，其强伸性能发生了一定的变化。文中系统地研究了拉伸处理及拉伸一定形处理对人发强伸性能的影响。结果表明，毛发拉伸保护剂对人发纤维具有明显地保护作用，从而使该拉伸改性工艺在较短的时间内得到较高的定形效果和较好的综合机械性能。     

Analysis of hair lipids and tensile properties as a function of distance from scalp

Cuticle cells form the outer covering surrounding and protecting the cortex. The cuticle cells are thin, flat and overlap, and intercellular lipid lamellae are found in the gaps between the cell boundaries. The lipid lamellae are also found within the cortex in the cell boundaries between the long fribrous corticle cells. In addition, the outer surfaces of the cuticle cells are covered by a monolayer of covalently bound fatty acids, a major component of which is 18-methyleicosanoic acid. The fatty acids are thought to be attached through thio-ester linkages. Together these lipids are thought to be major determinants of the physical properties of the hair. The present study tested the hypothesis that both free and covalently bound lipids are progressively lost during normal environmental exposures. This progressive loss within the cuticle layers may, in part, lead to an increased susceptibility of the protein and lipid lamellae in the cortex to degradation. This degradation, in turn, would contribute to a progressive decrease in the tensile properties of the hair. Research grade hair was cut into five segments from the root to the distal end. Lipids from each segment were extracted and analyzed by thin-layer chromatography in conjunction with photodensitometry. The major free polar lipid classes in the hair included ceramides, glucosylceramides and cholesterol sulfate. The concentrations of all of the free polar lipids as well as the covalently bound fatty acids decreased in going from the root to the distal end of the hair. In addition, there was a significant reduction in tensile properties of the hair from the root to distal end. In conclusion, the progressive loss of endogenous free and covalently bound lipids from hair, which are probably related to normal weathering of the hair and grooming practices, may help contribute to a marked decrease in tensile properties to the hair.     

Surface characterization of human hair by atomic force microscopy in the imaging and F-d modes

Surface structure and surface mechanical properties of human hair have been characterized by atomic force microscopy in the imaging mode and by force vs. distance, F-d, analysis. The effects of treatment by commercial conditioner/shampoo or by aqueous exposure have been investigated. The cuticular structure has been imaged at medium resolution; longitudinal striations with lateral spacings of 150-350 nm and vertical corrugations in the range 2-8 nm were observed at higher resolution. The features are similar to those observed for untreated wool fibre. Both adventitious debris/contamination and residues from cosmetic treatment can be imaged with resolution in the low-nanometre range. Removal of the cuticular surface layer from treatment with alkali solution, and subsequent imaging, revealed a fibrous substructure. F-d analysis of the surface is a rich source of spatially resolved mechanical and chemical information. Surface stiffness, and an equivalent Young's Modulus, E, can be inferred from the shape of the 'approach' tip-to-surface contact curve. A value of E of approximately 10 MPa was obtained for untreated hair. During aqueous exposure for 1 h the stiffness and modulus decreased by approximately a factor of 10. The discontinuity seen at 'lift-off' during the retract half-cycle of F-d analysis represents a measure of tip-to-surface adhesion. Adhesion decreased during aqueous exposure and was below the level of detectability after 1 h. Likewise, treatment by conditioner had the effect of lowering adhesion. High resolution F-d data revealed features that are consistent with the presence of a thin and readily compressible surface layer, probably analogous to the surface lipid layer on untreated wool fibre.     

Study of the optical properties of human hair

The optical properties of human hair were studied by photogoniometry. Starting from an optical model of hair, we developed a computerized method of decomposition of the goniophotometric curve. From our analysis we obtained structural parameters of the hair surface, average scale angle and cosmetic parameters like lustre and pigmentation. This method gave us new results in the following areas:
— the effects of bleaching on scale and internally reflected light;
— the study, from root to tip, of surface damage and hair pigmentation;
— the effects of stretching the hair on scale angle and lustre;
— the effects of sebum and dust on hair lustre.