Book

The Chemical and Physical Behavior of Human Hair

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Abstract

Human hair is the subject of a remarkably wide range of scientific investigations. Its chemical and physical properties are of importance to the cosmetics industry, forensic scientists and to biomedical researchers. The fifth edition of this book confirms its position as the definitive monograph on the subject. Previous editions were recognized as “concise and thorough” (Journal of the American Chemical Society), “an invaluable resource” (Canadian Forensic Science Society Journal), and “highly recommended” (Textile Research Journal). Chemical and Physical Behavior of Human Hair is a teaching guide and reference volume for cosmetic chemists and other scientists in the hair products industry, academic researchers studying hair and hair growth, textile scientists and forensic specialists. Features of the Fifth Edition: Recent advances in the classification and characterization of the different proteins and genes in IF and keratin associated proteins in human hair are described. The mechanism and incidence of hair growth and loss and hair density vs. age of males & females are described for Asians, Caucasians and Africans in different scalp regions. Details of hair surface lipids and cuticle membranes provide a better understanding of the surface and organization of the CMC and its involvement in stress strain is presented. Recent evidence demonstrates a more bilateral structure in curly hair and a more concentric arrangement of different cortical proteins in straighter hair. SNPs involved in hair form (curl and coarseness) and pigmentation and genes in alopecia and hair abnormalities are described. The latest biosynthetic scheme for hair pigments and structures for these and the different response of red versus brown-black pigments to photodegradation is described. A new method for curvature on 2,400 persons from different countries and groups is used to assign curvature throughout this book. Additional data for age and effects on diameter, ellipticity, elastic modulus, break stress and other parameters are presented with much larger data sets featuring statistical analyses. Hair conditioning, strength, breakage, split ends, flyaway, shine, combing ease, body, style retention, manageability and feel parameters are defined and described. A new section of different life stages by age groups considering collective and individual changes in hair fiber properties with age and how these affect assembly properties.

Chapters (10)

At or near its surface, hair fibers contain a thick protective cover consisting of six to eight layers of flat overlapping scale-like structures called cuticle or scales which consists of high sulfur KAPs, keratin proteins and structural lipids. The cuticle layers surround the cortex, but the cortex contains the major part of the fiber mass. The cortex consists of spindle-shaped cells that are aligned parallel with the fiber axis. Cortical cells consist of both Type I and Type II keratins (IF proteins) and KAP proteins. Coarser hairs often contain one or more loosely packed porous regions called the medulla, located near the center of the fiber. The cell membrane complex, the “glue” that binds or holds all of the cells together, is a highly laminar structure consisting of both structural lipid and protein structures. Hair fibers grow in cycles consisting of three distinct stages called anagen (growth), catagen (transition) and telogen (rest). Each stage is controlled by molecular signals/regulators acting first on stem cells and then on the newly formed cells in the bulb and subsequently higher up in differentiation in the growing fiber. The effects and incidence of hair growth and hair loss (normal and diseased) for both males and females are described in detail. Molecular structures controlling hair fiber curvature (whether a fiber is straight or curly) and the effects of the different structural units of the fiber on stress–strain and swelling behavior are described in detail.
Human hair consists of proteins, lipids, water, trace elements and pigments. The composition of the first four of these components is the focus of this Chapter. About two decades ago the emphasis on the proteins of hair was on its amino acid constituents which provided important information on the relative amounts of different functional groups in different types of hair and in different regions of the fiber. However, as a result of advances in the characterization and classification of the different proteins and genes of keratins and keratin associated proteins the focus today is on the proteins themselves. Several important new contributions to the composition of the surface layers of hair and the proteins of the cell membrane complex have been and are continuing and therefore are summarized in this Chapter. The current state of changes in the amino acids, proteins and lipids of hair by morphological region (including KAP and keratin proteins and where they reside), chemical and sunlight damage, diet, puberty and menopause, and other factors have been and are being made and are summarized here. An expanded section on metals in hair, where in the fiber these metals reside and the functional groups that they bind to and their effects on hair chemistry, toxicity and disorders are included.
The focus in this chapter is on hair form or fiber diameter and curvature and on hair color or pigmentation. These important hair characteristics are controlled by single nucleotide polymorphisms which are single nucleotide changes in genes. The three primary hair forms today (African, Asian and Caucasian) and their hair pigmentations arose from genetic mutations that are consistent with geographic migrations of Asians and Caucasians. Therefore, these hair forms and pigmentations are probably remnants of prior adaptations to temperature, sun exposure and other environmental influences. Other hair traits related to genetics including different alopecia and several genetically involved hair abnormalities are described along with a brief summary of current directions in forensic science which has expanded into DNA analysis and is moving into the analysis of SNPs.
The physical chemistry of the primary reactions involved in permanent waving and reductive and alkaline straightening and depilation of human hair are described in detail focusing on the disulfide bond its reduction/degradation, neutralization and subsequent reactions. The influence of mercaptan structure, excess reactant, pH and cysteine in different parts of the fiber on the chemical equilibrium in this reaction is explained. Factors affecting the kinetics of this reaction such as mercaptan structure, temperature, different hair types, hair swelling and hair condition, counterion effects, other reducing agents such as sulfite or bisulfite and side reactions of the reduction process are also described. The chemistry of alkaline straightening is contrasted to permanent waving including the importance of supercontraction to its permanence. Discussion of water setting, set and supercontraction and the swelling of hair (primarily transverse changes in the fiber) at different stages of these processes are also considered. The current understanding of chemical changes to the different morphological regions of hair, the cuticle, the cell membrane complex and the cortex of hair produced by these reactions is also described.
The physical chemistry of both chemical bleaching and sunlight effects on human hair are described. Recently we have become more aware of the critical involvement of free radical chemistry on both chemical and sunlight oxidative processes for human hair, therefore these effects are included. The beta layers of the cortical lipids with their high density of double bonds with allylic hydrogen atoms are very sensitive to free radical propagation reactions which can degrade the lipids themselves and also lead to protein degradation. Over the past decade our understanding of the biosynthesis and the structures of the melanin pigments has improved greatly; the most current biosynthetic pathway has been added to this Chapter. Initial oxidation reactions remove 18-MEA and free lipids from the surface and between cuticle cells. When metals like iron or copper are present free radical chemistry is increased leading to degradation of lipids and enhanced protein degradation not only at disulfide bonds but even at peptide bonds. Oxidative cleavage of disulfide bonds inside cuticle cells also occurs. Degradation of disulfide bonds inside cortical cells occurs next as well as degradation of hair pigments. Other amino acid functional groups are attacked and oxidatively degraded.
Shampoos and hair conditioners function primarily at or near the fiber surface. The primary function of shampoos is to remove soils or dirt from the hair surface, however, hair soils are highly varied from oily to particulate and the mechanisms for removal of these different soils also differ. Secondary functions of shampoos are also varied from conditioning the hair to dandruff control. With increasing damage to hair whether by chemical or photochemical reactions or even by abrasion, the hair surface becomes more hydrophilic and more acidic or anionic in character thus changing the affinity for different ingredients. Shampoos are often perceived as products that do not damage the hair; however damage can occur from some shampoos and such damage is described in detail. Different types of tests from laboratory to half head to tests on consumers are employed to evaluate the functionality of shampoos. These tests are described in detail with contrasts and some useful conclusions and insights. The sorption of shampoo and conditioning ingredients to hair including theories of sorption and diffusion are described in detail. Dandruff including scalp flaking, and skin irritation by surfactants is described in the last part of this chapter.
The different types of dyes described for human hair include, permanent or oxidation dyes, semipermanent dyes, temporary dyes or color rinses and other types of dyes either proposed for or used on human hair. The mechanism of oxidative dyeing of human hair is presented in detail describing a large number of different dye precursors and couplers and how they combine to form different dye species. Hydrogen peroxide and the new peroxymonocarbonate oxidative systems are presented. Different matrix compounds used in hair dyeing are also included. Regulatory activities related to oxidation hair dyes, described in this chapter, focus on the European community which has been the most active in the regulation of oxidation dye ingredients and provides periodic updates on the COLIPA website for safe and banned hair dye substances. Because of the increase in the aging population and the global sale of hair dye products to the graying population, a review of the initiation of hair graying including the age at which graying begins for different populations, the incidence of graying versus age in 5 year increments for different populations and graying among different geo-racial groups are also presented.
Polymers have become increasingly important components of cosmetics over the past few decades. The original uses of polymers in hair care were as fixative agents and viscosity controlling additives; however, new polymers today are also used for hair conditioning and for the development of new style control products. Polymer substantivity to hair fibers increases with molecular size, with an increasing number of polar group attachments and especially with an increasing number of cationic groups for attachment to the negatively charged surface of hair fibers. From an anionic shampoo medium the cationic charge on polymers is neutralized and the adsorbing species is essentially a neutral or negatively charged species. The most successful silicone conditioning polymers for hair care have been used in both shampoo and conditioner compositions. Dimethicones in shampoos condition undamaged or lightly damaged hair better than they condition highly damaged, bleached hair or even tip ends because neutral hydrophobic conditioning agents adsorb more readily to an undamaged hydrophobic surface than to a damaged highly polar hair surface. New block co-polymers and a fairly large number of new cationic polymers have been introduced into hair care recently, while fractal polymers (highly irregular shapes) and nanoparticles have been developed and are receiving attention for potential use in hair care.
This chapter describes tensile, bending and torsional testing including different parameters of each of these deformations and how these are affected by different types of hair including different types of hair damage. Expanded data sets are included for elastic moduli and other parameters of these deformations. A new section describing the historical development for assessing and measuring hair fiber curvature along with a new method for curvature has been developed and applied to more than 2,400 persons from more than 20 different countries. This method and data are featured in this section. Methods to determine the different dimensions of hair fibers including axial (length and curvature) and transverse dimensions (diameter, cross-sectional area and ellipticity) are described with much expanded data sets. Information on hair fiber friction (both high load and low load friction) and how friction varies with fiber diameter, comb composition and hair damage are included. Mechanical fatiguing, extension cycling and their effects on hair damage including scale lifting are described in the final section on the physical properties of hair fibers.
Herein is an attempt to bridge the gap between consumer and scientist by defining the more important consumer hair assembly properties (heads of hair, tresses, or wigs) describing how these properties are affected by changes from cosmetic treatments to fundamental single fiber properties. The effects of changes in single fiber properties by chronological age for five different stages of one’s life is also described in terms of how these fiber properties relate to and affect the important consumer hair assembly properties. The literature on hair breakage is also summarized as a multifactorial phenomenon involving tangle formation with hairs looped over other hairs, severe bending deformations, highly localized stresses, and the amount of water in the fibers. The effects of hair curvature, fiber twists, knots, hair damage and abrasive wear on hair breakage are also described. A new unpublished section describing split hairs found on the heads of consumers is described along with preferred mechanisms for the formation of these different types of split hairs.
... Hair has a unique pH property due to the types of amino acids forming the keratin of hair and also due to the difference in the chemical characteristics between the whole hair and the surface of hair (Robbins, 2012). The pH of the whole hair, the isoionic point, is 5.8 ± 1 which is primarily due to the higher amount of acidic amino acids than the basic amino acids in the whole hair (Hehner et al., 2002;Robbins, 2012). ...
... Hair has a unique pH property due to the types of amino acids forming the keratin of hair and also due to the difference in the chemical characteristics between the whole hair and the surface of hair (Robbins, 2012). The pH of the whole hair, the isoionic point, is 5.8 ± 1 which is primarily due to the higher amount of acidic amino acids than the basic amino acids in the whole hair (Hehner et al., 2002;Robbins, 2012). The pH of the surface of a healthy hair is pH 3.67 which is denoted as the isoelectric point of hair (Hehner et al., 2002;Morel et al., 2008;Robbins, 2012). ...
... The pH of the whole hair, the isoionic point, is 5.8 ± 1 which is primarily due to the higher amount of acidic amino acids than the basic amino acids in the whole hair (Hehner et al., 2002;Robbins, 2012). The pH of the surface of a healthy hair is pH 3.67 which is denoted as the isoelectric point of hair (Hehner et al., 2002;Morel et al., 2008;Robbins, 2012). The isoelectric point of hair is lower than the isoionic point of hair since there is a higher amount of acidic amino acid in the outermost cuticle layer compared to the whole hair (Robbins, 2012). ...
Article
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Basic Brown 16 pigment and three types of surfactants were used to prepare the cationic, nonionic, and anionic basic hair dyes. White hair and bleached hair were dyed using the three basic hair dyes and were shampooed 10 times using acidic, neutral, and alkaline shampoos prepared in the study. White hair and bleached hair dyed with the anionic basic hair dye resulted in a lower L *, a *, b * values and lower K/S values compared to the hair dyed with the cationic and nonionic basic hair dyes and the results were statistically significant at α = 0.05. Hair dyed with the anionic basic hair dye showed significantly higher Δ L *, Δ a *, Δ b *, and Δ E * ab values after 10 times of shampooing than those dyed with cationic and nonionic basic hair dyes (α = 0.05), indicating a lower color resistance for the anionic basic hair dye. Color difference after shampooing was significantly higher when alkaline shampoo was used (α = 0.05). Overall, the color difference after shampooing occurred more by the type of dye than by the type of shampoo.
... 19 The higher cysteine content causes increased disulfide bridge formation, resulting in greater mechanical strength, and thermal and chemical resistance. 20 The strength of the structures formed from keratin is also related to the formation of hydrogen bonds, coulombic interactions, van der Waals forces, and hydrophobic interactions present between the different amino acid residues. 21 These interactions can take place either between two separate chains or two portions of the same chain. ...
... Hair can be damaged in a variety of ways including environmental, chemical, overwashing, or thermal damage. 20 The amount and type of melanin pigments present determine the color of the hair. Oxidizing agents used in bleaching can oxidize and destroy the chromophore groups of melanin. ...
... The two most significant changes are the drop in half cystine residues and the increase in cysteic acid residues. 20 A hair treatment was reported in 2017 based on a range of gluconamides and their corresponding alkyl ammonium gluconate salts which were found to strengthen and repair damaged hair and prevent color leaching during drying. 24−26 The compositions comprise L-gluconic acid (GLA) and a range of different amines including ethylenediamine, ethanolamine, 3 -a m i n o -1 -p r o p a n o l , a n d t r i s ( h y d r o x y m e t h y l )aminomethane). ...
Article
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A hair care mixture formed from a gluconamide derivative and 3-hydroxypropyl ammonium gluconate is known to strengthen hair fibers; however, the mechanism by which the mixture affects hair is unknown. To give insight into the aggregation of the target gluconamide and potential interactions between the gluconate-derived mixture and hair fibers, a range of systems were characterized by X-ray crystallography namely two polymorphic forms of the target gluconamide and three salts of 3-hydroxypropylammonium with sulfuric acid, methane sulfonic acid, and oxalic acid. The gluconamide proves to aggregate and becomes a supramolecular gelator in aniline and benzyl alcohol solution. The resulting gels were characterized by rheology, scanning electron microscopy, proton nuclear magnetic resonance, Fourier transform infrared spectroscopy, and powder X-ray diffraction.
... Human hair has been increasingly the subject of research over the years, as there is a growing global interest in its properties, manipulations and applications by industry, the population increasingly sees hair as a symbol of self-esteem and beauty [1]. Hair is a natural biopolymer composed of a protein called keratin and its structure can be divided into four main regions: cuticle, cortex, medulla and cell membrane complex [2]. The outer region is formed by the cuticle, an amorphous material that has colorless cells shaped like "scales" overlapping, forming around 4 to 10 layers. ...
... The depth of 1 μm corresponds to the cuticle region, the depth of 3 to 20 μm corresponds to the cortex region reaching the medulla. There are some differences with increasing depth in the hair fiber, the band referring to the symmetric SS stretching (509 cm − 1 ) has higher intensity in the region near the cuticle, which is in agreement with what Robbins says [2], in which the concentration of cystine in the cuticular layers is higher when compared to the cortical area and medulla. Following this idea, the band at 665 cm − 1 , attributed to the C-S stretching, is also more intense in the cuticle region. ...
... Cysteic acid, represented by the SO band at 1044 cm − 1 , is one of the constituent amino acids of α-keratin [2], but its content can be intensified through photochemical oxidation given the exposure of the hair to radiation from natural sources (sun) or artificial (such as bleaching) sources [19], so in natural hair the intensity of this band is higher in the outer region of the hair (cuticle) and slightly weaker in the inner region (cortex and medulla), in bleached hair there is a considerable increase in this band, noting a higher concentration of cysteic acid formed, the band that appears at 978 cm − 1 after the bleaching of the hair is attributed to intermediate cystine oxides. Another band that is more intense after bleaching is the amide III band at 1248 cm − 1 , as it is attributed to the disordered conformation of the protein, indicating an increase in the Table 1 Raman and infrared vibrational tentative assignments (in cm − 1 ) for the bands observed in the spectra of natural white hair samples. ...
Article
Analytical studies on hair structures have evolved significantly over the years and vibrational spectroscopic techniques, such as Raman and infrared, have been increasingly used for such purposes. Nowadays, there is a need to understand more and more about the action of cosmetics on the hair fiber, so this work aims to analyze the permeation of cosmetic treatments into the hair. For the molecular structural characterization, Raman and infrared spectroscopy techniques were used, being verified the efficiency in the analysis of hair samples, demonstrating the internal characteristics of the fiber and the permeation of different cosmetics. Four cosmetics were chosen for this study and, due to the techniques used, it was possible to observe the diffusion of these products inside the bleached hair. It was observed with the Raman vibrational spectroscopy that the concentration of the products is found mainly in the cuticular region, decreasing the permeate content when approaching the central region, and the infrared spectroscopy showed results compatible with the Raman spectroscopy. Therefore, vibrational spectroscopy proved to be a valuable tool for the study of cosmetic permeation into the hair fiber and for the analysis of its external and internal structure.
... It is interesting to note that we know from conversations, that most colleagues within the hair cosmetics research community would agree that dry tensile testing has a lower sensitivity than wet testing to detect the effects of cosmetic treatments and processes (mainly chemical and thermal) [1,2,3,5,15,16]. However, the use of dry-testing is usually justified by the argument that ambient environmental conditions represent the usual conditions of hair in practice. ...
... On the basis of common practice [1,2,3,6,8,10,11,15,20,21,22] as well as of a recent investigation of the information content of wet tensile testing [17], we identified three specific variables as being especially suited for our investigation. These are elastic modulus (E), break extension (BE), and break stress (BS). ...
... This includes the drop of modulus with bleaching (compared to natural hair) when wet and its increase when dry [1,2,11,5,15,25]. ...
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Objectives: This investigation focusses, first, on the question to which extent wet and dry tensile tests on human hair may be considered as leading to independent results. Second, we try to assess the sensitivities of wet and dry testing to detect changes of mechanical properties. Specifically we were interested in separating changes, which were induced by a combination of a chemical (oxidation/bleach) and a physical treatment (heat). Methods: The basis for our study are data for the tensile properties (wet and dry) of a set of untreated and bleached hair tresses, which were submitted to the same schedule of thermal treatments. As characteristic tensile parameters, we chose modulus (E), break extension (BE) and break stress (BS). First, parameters were analysed across treatments for the correlations between wet and dry data. Second, we applied two-factor Analysis of Variance to assess the effects of the factors and their potential interaction. Results: Correlations for the dry vs wet data show only a weak relationship for E, while coefficients of determination (R2 ) are quite high for BE and BS. Two-factor ANOVA enables to quantify the various contributions to the Total Sum-of-Squares for all three parameters. We show that, the parameters respond quite differently to the chemical and the thermal treatments as well as to testing conditions (wet or dry). It is of interest to note that, the interaction between the chemical and the physical treatment is generally quite weak. For the interpretation of the results, we use the concept of the humidity-dependent as well as strain-induced glass transition of the amorphous matrix. Conclusions: The independence hypothesis for dry and wet tensile measurements only applies for modulus. Overall, we consider modulus (wet) as the best tensile measure of fibre damage when assessing chemical and/or physical treatments. Under ambient conditions (dry), break stress is shown to be a feasible alternative measure.
... Black hair contains predominantly eumelanin whereas red hair contains predominantly pheomelanin ("Melanin in hair", n.d.). Melanin pigment exists in the cortex of hair which occupies 90% of the hair structure (Robbins, 2012). To bleach hair, the bleaching agent must pass through the cuticle layer and penetrate into the cortex so that the chemical can destroy the melanin pigment through oxidation (Wolfram et al., 1970). ...
... Higher amount of protein leak suggests that the cuticle layer is opened up and the cell membrane complex (CMC) which protects the hair structure by filling the pores between the cells of cuticle and the cortex is partially destroyed (Robbins, 2012). This would allow the protein of hair to be damaged by chemicals such as cosmetic substances and leak through the pore openings (Robbins, 2012). ...
... Higher amount of protein leak suggests that the cuticle layer is opened up and the cell membrane complex (CMC) which protects the hair structure by filling the pores between the cells of cuticle and the cortex is partially destroyed (Robbins, 2012). This would allow the protein of hair to be damaged by chemicals such as cosmetic substances and leak through the pore openings (Robbins, 2012). Hydrogen peroxide reacts much faster with melanin than with keratin of hair (Wolfram et al., 1970). ...
Article
Effect of hair conditioner formulated with Argan oil or Camellia oil was investigated on the protection of hair damaged by bleaching. Six different rinse-off type hair conditioners were made with the basic ingredients of hair conditioner and one of the following conditioning agent; Argan oil (AO), Camellia oil (CO), Palmitic acid (PA), Stearic acid (SA), Oleic acid (OA), and Linoleic acid (LA). L*, a*, b* color values and tensile strength, elongation were measured, and the amount of protein leak was examined using the Bradford Protein Assay. Statistical significance was tested using the SPSS statistical software. Although both AO and CO were effective in protecting the tensile properties of bleached hair, significant effects were observed with AO in enhancing the tensile strength and retaining the color of bleached hair. This might be due possibly to the difference in the composition of four major fatty acids in Argan oil and Camellia oil.
... Hair predominantly consists of the structural proteins hard keratins (65-95% w/w) (Robbins 2012), that are subdivided into two types. Type I keratins possess a molecular weight (MW) of 40-50 kDa and an isoelectric point (pI) at acidic pH values. ...
... Type II keratins possess an MW of 55-65 kDa, a pI at neutral to slightly basic pH values and comprise 6 proteins (K 81-K 86) (Langbein et al. 2001;Schweizer et al. 2006). Keratins are particularly rich in cysteines that form a large number of intra-and intermolecular disulfide bridges (Lubec et al. 1987;Robbins 2012;Robbins and Kelly 1970). This high level of crosslinking is responsible for the structural rigidity and insolubility of hair (Lubec et al. 1987). ...
... The yield of the three biomarker peptides resulting from SM-incubated hair from 7 individuals (n = 3) varied noticeably (Fig. 4A). These differences were most presumable due to the variable composition of human hair consisting of 65-95% w/w keratin (Robbins 2012) as well as to the keratin-dependent extent of intermolecular disulfide crosslinks affecting the efficacy of lysis. However, alkylated peptides were found in high concentrations in the hair of each individual thus documenting the suitability of these biomarkers. ...
Article
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In the recent past, the blister agent sulfur mustard (SM) deployed by the terroristic group Islamic State has caused a huge number of civilian and military casualties in armed conflicts in the Middle East. The vaporized or aerolized agent might be inhaled and have direct contact to skin and hair. Reaction products of SM with plasma proteins (adducts) represent well-established systemic targets for the bioanalytical verification of exposure. The SM-derived hydroxyethylthioethyl (HETE)-moiety is attached to nucleophilic amino acid side chains and allows unambiguous adduct detection. For shipping of common blood and plasma samples, extensive packaging rules are to be followed as these matrices are considered as potentially infectious material. In contrast, hair is considered as non-infectious thus making its handling and transportation much less complicated. Therefore, we addressed this matrix to develop a procedure for bioanalytical verification. Following optimized lysis of SM-treated human scalp hair and pepsin-catalyzed proteolysis of adducts of keratin type I and II, microbore liquid chromatography–electrospray ionization high-resolution tandem-mass spectrometry (µLC–ESI MS/HR MS) was used to detect three alkylated keratin-derived biomarker peptides: AE(-HETE)IRSDL, FKTIE(-HETE)EL, and LE(-HETE)TKLQF simultaneously. All bear the HETE-moiety bound to a glutamic acid residue. Protein adducts were stable for at least 14 weeks at ambient temperature and contact to air, and were not affected by washing the hair with shampoo. The biomarker peptides were also obtained from beard, armpit, abdominal, and pubic hair. This is the first report introducing stable local peptide adduct biomarkers from hair, that is easily accessible by a non-invasive sampling process.
... Hair has a hierarchical protein structure that is composed mostly of α-keratin, with a high disulfide bond content which provides the fibre with high stability and strength [13]. A hair fibre can be broken down into three main sections: the outer cuticle, the inner cortex and the medulla, which may be absent in some hair types [14,15]. The cuticle is a chemically resistant barrier consisting of overlapping scale-like cells, with a hydrophobic coat of 18-methyleicosanoic acid [15][16][17]. ...
... A hair fibre can be broken down into three main sections: the outer cuticle, the inner cortex and the medulla, which may be absent in some hair types [14,15]. The cuticle is a chemically resistant barrier consisting of overlapping scale-like cells, with a hydrophobic coat of 18-methyleicosanoic acid [15][16][17]. The cortex encompasses 70-90 wt.% of the hair fibre's total mass, containing spindle-shaped cortical cells surrounded by a cell membrane complex [15,18]. ...
... The cuticle is a chemically resistant barrier consisting of overlapping scale-like cells, with a hydrophobic coat of 18-methyleicosanoic acid [15][16][17]. The cortex encompasses 70-90 wt.% of the hair fibre's total mass, containing spindle-shaped cortical cells surrounded by a cell membrane complex [15,18]. These cells in turn comprise crystalline keratin intermediate fibrils, which are embedded in an amorphous matrix of keratin-associated proteins [19][20][21]. ...
Article
The interactions between small molecules and keratins are poorly understood. In this paper, a nuclear magnetic resonance method is presented to measure changes in the ¹ H T 1 relaxation times of small molecules in human hair keratin to quantify their interaction with the fibre. Two populations of small-molecule compounds were identified with distinct relaxation times, demonstrating the partitioning of the compounds into different keratin environments. The changes in relaxation time for solvent in hair compared with bulk solvent were shown to be related to the molecular weight (MW) and the partition coefficient, LogP, of the solvent investigated. Compounds with low MWs and high hydrophilicities had greater reductions in their T 1 relaxation times and therefore experienced increased interactions with the hair fibre. The relative population sizes were also calculated. This is a significant step towards modelling the behaviour of small molecules in keratinous materials and other large insoluble fibrous proteins.
... Figure 2A shows the cuticle, the external part of the fibers, in which condition reflects in their shine and combability. 19,20 It also shows that repeated aesthetic hair treatments can lead to hair breakage, 19,21 and other scalp and hair disorders. 16 Figure 2B shows the overlap of the cuticle layers and cortex. ...
... Figure 2A shows the cuticle, the external part of the fibers, in which condition reflects in their shine and combability. 19,20 It also shows that repeated aesthetic hair treatments can lead to hair breakage, 19,21 and other scalp and hair disorders. 16 Figure 2B shows the overlap of the cuticle layers and cortex. ...
... The cortex includes fibrillar structures and other components, such as melanin, which provides color to the hair fiber, as well as supports the hair shaft. 19 The medulla is a soft protein layer, centrally positioned in the fiber, consisting of a large number of lipids. Its function in humans is not well known and it is not always found. ...
Article
Background Essential oils have great interest among the increasing demand for herbal cosmetics in the market. They are natural sources of biologically active ingredients due to the wide application of such compounds as well as their particular chemical composition. Several researches have evaluated the effectiveness of these bioactive ingredients for use in cosmeceuticals, mainly in both hair scalp and shaft hair damage repair. Thus, the amounts and their associations define the properties of these compositions with interest for hair cosmetic use, such as antioxidant, inflammatory, and antimicrobial activities. Because they are complex compounds, their actions on the skin, hair scalp, and shaft are not yet fully understood. Aims The purpose of this review is to highlight the relevant researches and findings on essential oils in hair care. Methods In order to achieve this objective, the present work comprises an updated bibliographic review related to essential oils used in hair care. Results It was possible to observe that cosmeceuticals containing essential oils applied to the scalp are preferably for topical activity. Also, it was noticed that there are few reports regarding their use in hair shaft. However, it was found that some oils are used to intensify the brightness and fix the hair color. Conclusions This work demonstrated that the use of essential oils in both cosmetic products (industrial application) and those associated with oils carriers (as individual protocols) may lead to satisfactory results in the treatment of some scalp dysfunctions.
... 30 They are generally classified in several types: bound (covalently bound to proteins), free (freely extractable by polar solvents), endogenous or exogenous, internal or superficial. 31 They belong to several chemical families: squalenes, wax esters, triglycerides, fatty acids (FA), cholesterol, ceramides, hydrocarbons, and Methyl Eicosanoic Acids (MEA). FAs represent the majority (60%) of hair lipids, followed by wax esters (20%) and hydrocarbons (10%). ...
... This finding agrees well with the composition of hair fatty acids (25% C 16 5% C 18 ) reported in the literature. 31 Next, we evaluated the acyl chain length. Predictions by CH 2 /CH 3 ratio and database search did not give the same results, the ratio giving much higher estimation (+8 CH 2 moieties on average). ...
... Then we used the (CH 2 )/(CH 3 ) ratio for each individual medulla to determine the number of methylene groups using the calibration curves. Since the longest literature-reported aliphatic chain is C36 for hair, 31 we eliminated higher values as outliers (n = 11, 8%). We found that medullas without detectable carboxylate signal had mostly 8, 14 and 16 CH 2 moieties (average chain length 16 CH 2 , median 17, min 8, max 25, n = 35). ...
Article
Human hair is an organ that connects fundamental and applied research with everyday life through the cosmetic industry. Yet, the accurate compositional description of the human hair medulla is lacking due to their small size and difficulty with microextraction. Medullas are thus generally classified based on morphology. We investigated the chemical composition of the human hair medulla using synchrotron based infrared microspectroscopy. We confirmed that lipid signatures dominate the medulla infrared spectrum having 3-20 times higher lipid concentration compared to their surrounding cortex. Human hair medullas contain a mixture of non-esterified and esterified lipids, and carboxylate soaps in various proportions. We reveal the first direct spectroscopic evidence that medulla carboxylates are coordinated to calcium since they exhibit the specific calcium carboxylate signature. Using a representative sample, we observed a strong compositional variability between medullas that was unreported before. We detected calcium carboxylates in 76% of the medullas with one order of magnitude concentration variability between samples. All medullas contained esters with esterification varying by a factor of 30. Moreover, we detected the presence of crystalline calcium stearate in 9% of the medullas. We described a series of spectral markers to characterize medullas based on their lipid composition and propose to classify medullas in four to five groups. Our analysis provides a more detailed understanding of the chemical composition of human hair medullas that may impact cosmetics and biology. The origin and biological meaning of these variations must still be investigated.
... DOI: 10.1002/adpr.202200161 ...
... Human hair contains many forms of amino acids. [10] With the bulk of human hair comprising keratin, KAPs with the ability to absorb UV excitation and undergo photochemical reactions are highly relevant to the phenomenon observed in this work. Out of these KAPs, L-tryptophan, [12] that exists mainly in the cortex, and L-cystine and [13] L-tyrosine, [14] which have a strong presence in the cuticle and cortex, [15] are of particular interest to us. ...
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Human hair is a huge untapped waste resource whose useful compounds require toxic and environmentally harmful chemicals to extract. Herein, the optical properties of human hair without using such chemicals, turning waste into a site‐selective multicolored display, and a chemical sensor with a visual indicator through tunable fluorescence are transformed. The tunable fluorescence color, which includes both visible light and infrared components, is achieved using a scanning laser beam (microscopic) and hotplate heating at a low temperature of 360 °C for 3 min (macroscopic and large‐scale production). These fluorescing hair readily detects methylene blue molecules within a concentration range of 10−12–10−21 M due to the formation of tryptophan byproducts and electron contributing pyrrolic nitrogen. This work's simple yet impactful consequence lays the foundation on which the industrial applicability of the functionalized human hair waste can be achieved, realizing a possible cyclical economy through sustainable resources. A simple thermal anneal process achieves large‐scale tuning of human hair's fluorescence. Microscopic fluorescence sculpting is realized with the help of a focused laser beam. With new insights into the working mechanism of such phenomenon, fluorescing heated white hair, with five times stronger emission than black heated hair, readily transforms into a sensor for methylene blue molecules with high sensitivity.
... H air is an integrated system in terms of its structure and its chemical and physical behavior [1] [ Figure 1]. The tensile behavior of human hair is determined largely by the cortex which lends mechanical properties such as tensile strength and elasticity to the hair fiber. ...
... On the other hand, intercellular diffusion involves penetration between cuticle cells through the endocuticle and the CMC protein structures and is the preferred route for large molecules. [1] The practice of oiling scalp hair is very prevalent in India. This consumer habit is not merely to enhance beauty, it is more of a traditional ritual which is passed down the generations. ...
Article
Aim: The aim of this study is to identify a new method to measure oil penetration into hair, compare penetration ability of two types of oil: Type 3 hair oil and coconut oil into the hair shaft and explore its correlation to a physical property of hair, tensile strength. Materials and methods: The study utilizes the measurements of two parameters, thickness, and cohesive force to define penetration of oil. The hypothesis was that an increase in hair fiber thickness along with reduction in cohesive force would indicate higher penetration of oil into the hair strand. The tensile strength of hair was then determined by measuring the behavior of treated hair strands while an axial stretching load was applied. Results: In experiment of hair thickness measurement, there was a significant increase in the hair fiber thickness post oil application in both the test oils as compared to baseline (untreated control). However, this increase was higher in hair swatches treated with Type 3 hair oil. For cohesive force measurement, significantly lower force was required for hair swatches treated with Type 3 hair oil when compared to coconut oil. For tensile strength, both test oils exhibited increase versus baseline but increase in tensile strength was significantly more with type 3 hair oil when compared to coconut oil. Conclusions: The present study shows that conjoint assessment of hair thickness and cohesive force post oil application can be a suitable method to indicate the extent of oil penetration into the hair. Overall, the study indicated the positive influence of oil penetration on hair strength.
... In ancient tombs, the basic structure of the keratin filaments of human hair may remain unchanged over centuries and its essential structural features are extraordinarily stable. However, as a person ages, a change in state of the growing hair occurs that is expressed in decrease of their density (hair loss or alopecia), hair graying, thinning tends (finecoarseness) and dryness/oiliness of the scalp and the hair [25]. The hair disorders are associated with a number of possible reasons. ...
... Weathering of cystine in hair is primarily a photochemical reaction proceeding mainly through the C-S fission producing cystine S-sulfonate residues as a primary end product. Due to photo-protective effect of melanin, protein photooxidation has less intensity in black hair than in light hair [25,59]. ...
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In this review article, the recent approaches to nanoarchitectonics on hair are briefly overviewed. Different types of nanomodifications can be used for the cosmetic and medical applications to provide the aesthetic improvement or treatment of hair and scalp diseases. This article will discuss in detail the various aspects of nanostructures using to enhance the effect of daily care products, to increase the efficiency of penetration of active substances into the hair structures responsible for their regeneration. In general, nanocoatings are promising in the field of application for improving the structure and aesthetics of the hair shaft, as well as for imparting various beneficial properties to hair or for protection from harmful environmental factors. Finally, the approaches of nanoarchitectonics and regenerative medicine will be overviewed from the point of effective methodology for the regeneration of hair follicles creation.
... Specifically, for the study we present here, we used a laser ablationinductively coupled plasma-mass spectrometry analysis of single hair strands to capture the temporal dynamics of metal metabolism. Hair strands grow in an incremental manner at a rate of approximately 1 cm per month, with some variation by age, gender, race, and growth cycle [19]. By rastering a laser along the length of the hair strand and analyzing the ablated material with a mass spectrometer, we generated 4-6 hourly sequential profiles of metal uptake for every participant ( Figure 1). ...
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Autism spectrum disorder (ASD) is a neurodevelopmental condition diagnosed in approximately 2% of children. Reliance on the emergence of clinically observable behavioral patterns only delays the mean age of diagnosis to approximately 4 years. However, neural pathways critical to language and social functions develop during infancy, and current diagnostic protocols miss the age when therapy would be most effective. We developed non-invasive ASD biomarkers using mass spectrometry analyses of elemental metabolism in single hair strands, coupled with machine learning. We undertook a national prospective study in Japan, where hair samples were collected at 1 month and clinical diagnosis was undertaken at 4 years. Next, we analyzed a national sample of Swedish twins and, in our third study, participants from a specialist ASD center in the US. In a blinded analysis, a predictive algorithm detected ASD risk as early as 1 month with 96.4% sensitivity, 75.4% specificity, and 81.4% accuracy (n = 486; 175 cases). These findings emphasize that the dynamics in elemental metabolism are systemically dysregulated in autism, and these signatures can be detected and leveraged in hair samples to predict the emergence of ASD as early as 1 month of age.
... 53 Various studies confirmed that in the case of hair bleaching, the amount of cysteine decreases, and the amount of cysteic acid increases. 54 We found chlorinated tyrosines after treatment with Cl 2 , NaOCl (and household bleach), and sulfuryl chloride; however, as described above, an optimal marker would be specific for exactly one chemical. In the absence of one specific marker, one can in principle also use a combination of different markers, if these are sufficiently different between the respective samples. ...
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Chlorine, as a dual-use chemical, is an essential industrial chemical which has been used as a chemical weapon in the past due to its toxicity and availability. The retrospective verification of chlorine intoxication is often especially challenging, and unambiguous markers are still missing. In this study, the effects of different chlorinating and oxidizing agents on human hair were investigated. Samples were exposed to a variety of chlorinating chemicals for a short time and then completely hydrolyzed by a HBr solution to break down their keratin proteins into individual amino acids. After derivatization and targeted liquid chromatography-mass spectrometry analysis, 3-chlorotyrosine and 3,5-dichlorotyrosine were unambiguously identified from human hair exposed to chlorine, hypochlorite, and sulfuryl chloride. Our results show long-term stability of these markers in the biological matrix, as the chlorotyrosines can still be found 10 months post-exposure at the same levels. Finally, an untargeted analysis was able to discriminate between some of the different intoxicants.
... The literature has consistently report straight and wavy hair as being stronger than curly, coily, and kinky hair. [39][40][41] The mechanical properties measured in these studies reported that Young's modulus (E), tensile strength (σ) and fracture point decrease with increasing degree of curliness, while friction coefficient increases with degree of curliness. Thus, hair breakage and damage from mechanical manipulation has been widely reported and commonly experienced by people with curly, coily, and kinky hair. ...
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Hair is one of the key characteristics that classify us as mammals. It is a natural polymeric composite that is primarily composed of tight macro-bundles of keratin proteins, which are highly responsive to external stimuli, including pH, temperature, and ionic solvent content. The external responsive behavior displayed by hair is similar to the behavior displayed by hydrogels and other natural fibrous gel systems like collagen and fibrin. Hair and its appearance play a significant role in human society. It is a highly complex biocomposite system, which has been traditionally challenging to characterize and thus develop functional personal care products for consumers. Over the last few decades, a significant societal paradigm shift occurred among those with curly hair. They began to accept the natural morphological shape of their curls and style their hair according to its innate, distinct, and unique material properties. These societal and cultural shifts have given rise the development of new hair classification systems, beyond the traditional and highly limited ethnicity-based distinction between Caucasian, Mongolian, and African. L’Oréal developed a hair typing taxonomy based on quantitative geometric parameters displayed among the four key curl patterns – straight, wavy, curly, and coily (kinky). However, the system fails to capture the complex diversity of curly and kinky/coily hair. Acclaimed celebrity hair stylist, Andre Walker, developed a classification system that is the existing gold standard for classifying curly and kinky/coily hair, however the system relies upon qualitative classification measures, making the system vague and ambiguous to the full diversity of phenotypic differences. The goal of this research is to use quantitative methods to identify new geometric parameters, which will be more representative of curly and kinky/coily hair curl patterns. These new parameters will therefore provide more information on the kinds of personal care product ingredients that will resonate best with these curl patterns, and thus maximize desired appearance and overall hair health. The goal is also to correlate these new parameters with its mechanical properties. This was accomplished by identifying new geometric and mechanical parameters from several types of human hair samples. Geometric properties were measured using scanning electron microscopy (SEM), photogrammetry, and optical microscopy. Mechanical properties were measured under tensile extension using a texture analyzer (TA) and a dynamic mechanical analyzer (DMA), which bears similarity to the common act of brushing or combing. Both instruments measure force as a function of applied displacement, thus allowing the relationship between stress and applied stretch ratio to be measured as a hair strand uncurls and stretches to the point of fracture. From the resulting data, correlations were made between fiber geometry and mechanical performance. This data will be used to draw more conclusions on the contribution that fiber morphology has on hair fiber mechanics and will promote cultural inclusion among researchers and consumers possessing curly and kinky/coily hair.
... The ZnPT particles were platelet in shape as revealed by cryo-SEM. The shampoos differed to the aqueous ZnPT as the particles were finer (Cedel > H&S > T/Gel) and existed as a stabile dispersion [31][32][33]. Industry reports suggest that the optimal ZnPT particle size for surface delivery is approximately 2.5 µm which is similar to the range we observed of 1.0-3.3 ...
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Zinc pyrithione (ZnPT) is a widely used antifungal, usually applied as a microparticle suspension to facilitate delivery into the hair follicles, where it then dissociates into a soluble monomeric form that is bioactive against yeast and other microorganisms. In this study, we use multiphoton microscopy (MPM) and fluorescence lifetime imaging microscopy (FLIM) to characterise ZnPT formulations and map the delivery of particles into follicles within human skin. To simulate real-world conditions, it was applied using a massage or no-massage technique, while simultaneously assessing the dissolution using Zinpyr-1, a zinc labile fluorescent probe. ZnPT particles can be detected in a range of shampoo formulations using both MPM and FLIM, though FLIM is optimal for detection as it allows spectral and lifetime discrimination leading to increased selectivity and sensitivity. In aqueous suspensions, the ZnPT 7.2 µm particles could be detected up to 500 µm in the follicle. The ZnPT particles in formulations were finer (1.0–3.3 µm), resulting in rapid dissolution on the skin surface and within follicles, evidenced by a reduced particle signal at 24 h but enhanced Zinpyr-1 intensity in the follicular and surface epithelium. This study shows how MPM-FLIM multimodal imaging can be used as a useful tool to assess ZnPT delivery to skin and its subsequent dissolution.
... Human hair is a complex material with hierarchical structures based on fibrous keratin building blocks, i.e. α-helical protein filaments rich in cysteine units, which aggregate into larger textures and interconnect via disulfide bridges. 1 The outer part of the hair, the so-called "cuticle", consists of three sublayers (epi-, exo-, and endocuticle) and generally serves the purpose of protection against environmental stresses. 2 The outermost epicuticular domain is additionally covered by a layer of 18methyleicosanoic acid (18-MEA, the so-called "β-layer"), longchain lipids that are bound to the protein network via thioester linkages with cysteine units. ...
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In the light of clean beauty and sustainability requirements emerging in the personal care market, the urgent need for the replacement of silicones in hair conditioners-with comparable performance and customer experience-has been highlighted in the industry. In this context, the goal of the present study was to investigate the physical effects of different silicone-free conditioner formulations on Mongolian hair after damage due to bleaching and compare the results to property changes induced by a classical silicone-containing formulation. To that end, the morphology, structure, and composition of strands and individual fibers of this hair type were characterized before and after bleaching by means of optical microscopy, atomic force microscopy (AFM), and X-ray photoelectron spectroscopy (XPS). It is shown that oxidative bleaching causes significant damage to the native hair surface, leading to local depletion or even large-area removal of the outer hydrophobic lipid layer. This results in enhanced wettability of the bleached hair by water (as confirmed by contact angle measurements) and is accompanied by an undesired loss of hair gloss and softness. Upon treatment with suitable cosmetic emulsions, the natural hydrophobicity of intact Mongolian hair can be partially or fully restored, with silicone-free formulations having effects similar to those of established silicone-containing products. The successive influence of bleaching and conditioning was further monitored using inverse gas chromatography (iGC), a technique that probes changes in surface energetics and polarity over an ensemble of an entire hair strand through interactions with specific molecules at the solid/gas interface. The resulting data mirror the macroscopic behavior of the bleached/conditioned hair and provide a quantitative scale for measuring damage and repair effects. Most notably, the effect of bleaching and subsequent conditioning on the haptic perception of hair strands could also be quantified with the aid of a biomimetic measurement system, which identifies increased friction (both tactile and sliding) as the major cause for the strawy feel of bleached hair and indicates successful relubrication after treatment with suitable conditioner formulations. Finally, the different physical properties determined for native, bleached, and reconditioned Mongolian hair are found to be reflected in application-oriented tests, namely in vitro measurements of wet and dry combing work. Overall, the data collected in this work shed novel light on the surface properties of Mongolian hair and highlight that effective hair conditioning after damage can be achieved without silicones in advanced cosmetic emulsions based on octyldodecyl myristate and glyceryl oleate.
... It is mainly composed of β-keratins, inelastic proteins, and its major function is to protect the inner cortex [20] . The cuticle is formed by dead, flat overlapping cells arranged in a multilayered scaled structure [23] . The outer surface of these scale cells is coated by a 10-14 nm thick lipoprotein layer called epicuticle [24] . ...
... Surface lipids within the 18-methyl eicosanoic acid (18-MEA) lipid layers of hair are removed during shampooing. 16 Though internal lipids stay unaffected initially, repeated shampooing can affect them. ...
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p>Modern shampoos are much more than just cleansing agents. With rising demands for new milder and ‘greener’ products, the developments in the field of shampoo and conditioners are moving at a faster pace than ever before. Soaps were initially used to clean scalp but are not recommended for hair cleansing because they leave behind a soap scum when mixed with hard water that is difficult to rinse from the hair and scalp. There are different types of shampoos. Besides “normal” cleaning shampoo, there are “specific” shampoos that have additional ingredients targeting some hair problems. Dermatologists most frequently prescribe shampoos but little is taught in medical schools about the hair cosmetics. Most of the prescriptions are based only on the treatment of the scalp and usually disregards the hair fibre health. Hence it is imperative for dermatologists to known about the mechanism of shampoos, different surfactants and where to choose which shampoo.</p
... During aging, hair loss is quite natural and common however it causes great concern to people. Due to several lifestyle related changes such as stress, anxiety, consumption of junk foods, use of various hair styling/coloring procedures etc., the younger generations have started to suffer from serious hair loss problem [3,4]. In most instances the hair loss is not transient, but it results in alopecia. ...
... Eumelanins have been identified in a range of organisms including: marine cephalopods (Palumbo and Yeh 1994); humans, a fact that can be easily seen by hair color in juveniles due to the abundance of pigment (Robbins 2012); the exocuticle of insects (Nappi and Sugumaran 1993); and some groups of bacteria, such as Streptomyces antibioticus, in which the production of eumelanin can also be used in taxonomic identification (Chen et al. 1992). ...
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Melanin is a heteropolymer formed by the polymerization of phenolic and indolic compounds. It occurs in organisms across all biological kingdoms and has a range different of functions, thus indicating its important evolutionary role. The presence of melanin offers several protective advantages, including against ultraviolet radiation, traumatic damage, oxidative stress, extreme temperatures, and pressure. For many species of fungi, melanin also participates directly in the process of virulence and pathogenicity. These organisms can synthesize melanin in two main ways: using a substrate of endogenous origin, involving 1,8-dihydroxynaphthalene (DHN); alternatively, in an exogenous manner with the addition of L-3, 4-dihydroxyphenylalanine (L-DOPA or levodopa). As melanin is an amorphous and complex substance, its study requires expensive and inaccessible technologies and analyses are often difficult to perform with conventional biochemical techniques. As such, details about its chemical structure are not yet fully understood, particularly for nematophagous fungi that remain poorly studied. Thus, this review presents an overview of the different types of melanin, with an emphasis on fungi, and discusses the role of melanin in the biology and ecology of nematophagous fungi.
... This preliminary extension of the HPP methodology provides a foundation for future studies. Moreover, the regional segregation of HPPs may reflect well-recognized regional differences in the rate of HS formation (Robbins, 2012). Thus, future models may also be able to leverage information contained within HPPs from non-greying hairs and make specific inference from hairs collected across scalp regions. ...
Article
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Background: Hair greying is a hallmark of aging generally believed to be irreversible and linked to psychological stress. Methods: Here, we develop an approach to profile hair pigmentation patterns (HPPs) along individual human hair shafts, producing quantifiable physical timescales of rapid greying transitions. Results: Using this method, we show white/grey hairs that naturally regain pigmentation across sex, ethnicities, ages, and body regions, thereby quantitatively defining the reversibility of greying in humans. Molecularly, grey hairs upregulate proteins related to energy metabolism, mitochondria, and antioxidant defenses. Combining HPP profiling and proteomics on single hairs, we also report hair greying and reversal that can occur in parallel with psychological stressors. To generalize these observations, we develop a computational simulation, which suggests a threshold-based mechanism for the temporary reversibility of greying. Conclusions: Overall, this new method to quantitatively map recent life history in HPPs provides an opportunity to longitudinally examine the influence of recent life exposures on human biology. Funding: This work was supported by the Wharton Fund and NIH grants GM119793, MH119336, and AG066828 (MP).
... The lipid components of hair, produced in the hair bulb, are formed from sterols, fatty acids and ceramides. This mixture of triglycerides, waxes and squalene form a film on the surface of the skin and lubricate the hair, thus preserving its suppleness and sheen [14,15]. Fig. 1.3a & b shows analogous IR absorption patterns for Datura metel hexane flower and leaf extracts. ...
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Datura metel is a green leafy plant that has reportedly been employed for its medicinal and toxic properties. In this study, dried and pulverized Datura metel leaves and flowers were extracted using n-hexane and methanol, and then characterized. Methanolic leaf extract had the highest percentage recovery yield (23.5%). Phytochemical tests on both sets of extracts revealed the presence of Flavonoids, Tannins, Glycosides, Alkaloids, Phenols, Saponins and Reducing sugars. The methanolic portions contained Steroidal compounds in the flowers but not in the leaves while Terpenoids were absent in the flowers but present in the leaves. Animal treatments with methanol leaf extract initiated the fastest hair growth in 5 days, and the shaved areas were completely filled with hairs in 13 days. Hexane flower extracts produced the longest regrowth hairs (80.6%) after 30 days. Methanol leaf extracts also caused mass switching of 60% hair follicles from resting telogenic (T) to growing anagenic (A) phases with T/A ratio 0.45. The results plainly demonstrate that D. metel leaf and flower extracts have complementary effect in inducing actively growing cyclic phases, finer and denser hairs.
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Global climate change is already affecting the environment, as glaciers are receding, ice on rivers and lakes is melting, plant and animal range`s have altering, and trees are blooming early. Therefore, focus has shifted towards sustainable materials. There is a growing desire for materials that have a unique combination of qualities that metals, polymers, and other materials cannot provide, therefore scientists are turning their focus to green composites. Green composites offer a wide range of uses in automotive, aerospace, and marine applications. Composites are multiphase resources with separate interfaces that contain chemically different materials. Composites are made up of a variety of materials that are distinct in nature, and they give a set of desirable features that are superior to those of their predecessors or parents. Natural fibers are less expensive, more readily available, rust-resistant, plentiful, nontoxic, and safe for human skin, eyes, and respiratory systems. Green composites are created by combining renewable fibers with polymers (matrix) to create a new class of composites known as “green composites.” This review includes studies on various animal-based fibers and their applications. In this article, recent advancements in the field of these fibers and their composites of fibers are also discussed. The physical, chemical, and mechanical properties are also discussed in this paper. Moreover, the benefits and drawbacks of using these fibers are also discussed in detail. Finally, the paper gives an outline of the topic. The results from composites constructed from each fiber are provided, along with appropriate references for more in-depth analysis studies. This review is specially performed to strengthen the knowledge bank of the young researchers working in the field of natural composites.
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Besides the differences in skin and hair color among different ethnic groups, morphological and functional differences in skin and hair have also been demonstrated. The color of skin and hair is determined by two types of melanin, eumelanin (brown to black pigment) and phaeomelanin (red to yellow pigment). In addition to the individual mixture of these pigment types, there are also differences in the melanosome arrangement of Caucasian, Asian, and African skin. Although the epidermis thickness is the same in all people, darker skin has a higher number of stratum corneum layers and a thicker dermis with a higher number of fibroblasts. The hairs of different ethnic groups also vary regarding shape and thickness: they are round in Asians, elliptical in Blacks and intermediate in Whites. Hair diameter is the greatest in Asians, followed by Blacks and is the smallest in Whites, whereas the number of hairs is highest in Whites, followed by that in Asians and Blacks.
Chapter
Die Zeitschrift Landlust ist mit einer Auflage von derzeit etwa 800.000 Exemplaren einer der erfolgreichsten Titel auf dem deutschen Printmedienmarkt. Sie generiert Ländlichkeit als idyllischen Schutzraum: ein Land ohne Gewerbegebiete, Fleischfabriken und Verkehrstote – und dem Anschein nach auch weitgehend ohne Migration. Der Beitrag untersucht, wie viel Migration dieser Schutzraum zulässt und hinterfragt dabei auch das eigene Wahrnehmungsdispositiv, das ‚Migration‘ als sichtbare Kategorie voraussetzt.
Chapter
Human hairs are commonly collected from crime scenes and sent to a forensic laboratory for analysis. However, most of them are at the relatively quiescent telogen growth phase with little to no soft tissue remaining at the root end for nuclear DNA analysis. Since neither microscopical hair shaft comparisons nor mitochondrial DNA sequencing constitute a basis for personal identification, other complementary methods will be beneficial. This book chapter explores promising protein sequencing alternative methods for questioned and known hair shaft comparison.
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This study focused on black and white hairs in individuals over the age of 40 and analyzed qualitative changes of age-related hair. Water-related irregular shapes increased with aging for both high-and low-humidity conditions. Careful observance of the difference between black and white hair revealed that the water-related irregular shape of white hair increased. The result of real-time examinations of water behavior by means of Fourier-transform infrared (FT-IR) microscopy revealed an increase of water penetration and decrease of water holding capacity in white hair. The amount of carbonylated proteins, which have been known an indicator of aging, was significantly greater in white hair than black hair over the age of 50. These results suggested that the carbonylation of interior proteins changed water behavior and was the cause of hair shape. Furthermore, it was considered until now that carbonylated proteins could not return to their previous form, but reductive amination treatments using 5-ethyl-2-methylpyridine borane (PEMB) were revealed to reduce the amount of carbonylated proteins, improving water behavior and hair shape. From the above, further quality-of-life (QOL) improvements can be brought about by not only applying color correction to white hair with conventional coloring, but also combining this with hair shape correction based on reductive amination.
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The present study evaluated the total energy output and economic feasibility of biodiesel production coupled with value-added nitrogen-containing compounds (NCCs) through co-pyrolysis of low- and high-protein biowaste. Corn straw (CS) and human hair waste (HW) were used at different blend ratios of 0%, 25%, 50%, 75%, and 100%, w/w. Individual pyrolysis of HW showed 20.7% higher bio-oil yield than CS due to higher volatiles in HW, while co-pyrolysis resulted in synergistic action which enhanced both bio-oil yield with higher fatty acids/esters proportion. The highest recorded bio-oil yield was 46.3% using 75% HW blend ratio, which showed insignificant difference with that of HW. In addition, co-pyrolysis resulted in reduction of NCCs by 13.7% comparing to HW, with simultaneous enhancement of fatty acids and esters contents by 67.8% and 13.2%, respectively. Therefore, transesterification of co-pyrolyzed bio-oil showed the highest biodiesel proportion of 20.7%, representing 4.7-times and 61.7% higher than CS and HW, respectively. In addition, transesterified co-pyrolyzed bio-oil showed 27.0% NCCs, which was 8.2-times higher than that of CS. Due to the higher calorific value of biodiesel compared to bio-oil, biodiesel of the co-pyrolyzed bio-oil showed the highest total energy output in the biorefinery route (3753 MJ/ton biomass), which was higher than the total energy output from the conventional route of bio-oil production from CS (3738 MJ/ton biomass). However, additional revenue of 39,860 US$/ton biomass was estimated in the biorefinery route due to NCCs fraction, which provides a new insight towards future industrial applications.
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When developing a procedure to identify external contamination of hair as opposed to drug that is in hair from ingestion, there are components of the process that must be considered in the final method. A method that does not achieve the objective may be missing one or more of these elements: choice of solvent, a drug-binding agent, ratio of solvent to hair, temperature, time, intactness of the hair, and establishing, for the chosen method, a criterion based on the drug contents of the wash and hair that indicates the hair may be contaminated.
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Trace elemental research in human hair has been the subject of numerous investigations and biomonitoring for forensic science, medical science, cosmetics, archeology, environment and other purposes. This chapter presents a brief introduction to human hair, its sample preparation, X‐ray fluorescence (XRF) analysis on human hair, and some associations of trace elements in hair and physical health of human. XRF spectrometry is a well‐established analytical technique for multi‐elemental analysis of forensic, metallurgical, biological, geological, mining, archeological, and environmental samples. Trace elements in the human body serve both general functions with a structural material and with regulating the biological activities of the body. Due to the development of high‐sensitivity XRF spectrometers, modern X‐ray fluorescence techniques could one day dominate the study of biological samples in various fields such as clinical, forensic, and environmental science.
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Hair lipid composition varies by ethnic hair type and by hair layer. Lipids in the cuticle, cortex, and medulla of the hair shaft provide a protective barrier to environmental and chemical damage, prevent hair breakage and desorption, and affect the elastic and tensile properties of hair. The aim of this systematic review is to provide an overview of the lipid composition and ethnic differences of human hair, effects of external damage on lipid content and properties, and changes in hair lipid composition associated with disease states. PubMed/MEDLINE was searched up to March 2021 according to PRISMA guidelines for articles discussing the lipid content of human hair and effects of physical, chemical, or environmental damage, and disease. Fifty‐nine articles investigating the lipid content of hair were included for review. Lipids affect fluid permeability, hydration, strength, and texture of ethnic hair fibers. Lipid loss is accelerated by hair‐damaging treatments such as bleach, dye, perm, straightening, and surfactant use, and sun and aging processes, leading to dehydrated, breakable, disordered, and dull hair. Diseases including acne, alopecia, and breast, gastric, prostate, lung, and rectal cancers display elevated hair lipid levels. Lipids are vital in protection against damage and maintenance of healthy hair. Further studies are needed to investigate the effects of lipids on the structural properties of ethnic hair, and changes in hair lipid composition with various dermatologic and systemic diseases.
Chapter
Permanent hair waving is a chemical/mechanical treatment aimed at modifying hair protein to achieve and retain curly shapes. Women with straight hair purchased expensive wigs or spent hours for hair ondulation with water and heat for a temporary success. Scalp hair is visualized as a circular fiber but cross‐sections of individual hairs reveal variation in hair shape. Hair fibers undergo longitudinal aging when exposed to external factors such as grooming or environmental influences. Permanent waving products contain an elaborate mixture of ingredients to make the reactions controllable and appropriate for different hair types, such as normal hair, sensitive hair, coarse hair, and colored/bleached hair. Reducing agents, most commonly ammonia or sodium salts of thioglycolic acid have been used since the late 1950s to avoid skin and hair irritation while producing a lasting hair curl. Acidic and neutral permanent wave preparations mostly contain glycerol monothioglycolate as reducing agent.
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Hair coloring products adopt various type of dyes with different characteristics. The mainly used oxidative dyes show promising basic performance, while typically giving dull color look. Dissociative azo dyes; HC Red 18, HC Blue 18 and HC Yellow 16, which have high chroma, and work in alkaline peroxide system were developed. In addition to the known challenges of the conventional direct dyes, such as dyeing level and skin-staining, stability to the alkaline peroxide was carefully considered. As a result, the dyes can be used in the same way as oxidative dyes, that is, simultaneous bleaching and coloring of the hair. An anionic charge on the hydroxyl group of the dyes can be delocalized onto their conjugated system. The said delocalized charge distribution allowed the dyes to penetrate to the hair cortex and enabled their long-lasting color durability. Cross-sectional observation of the dyed hair showed multi-layered penetration pattern of the dyes in the hair cortex. This penetration pattern provides “Moving Color” effect, which is, angle-dependent hair color look depending on the hair/observer’s position.
Chapter
Aflatoxins pose serious health implications on all age groups, and therefore the exposure assessment of aflatoxins through all means is essential. Human exposure of aflatoxins is mainly through the ingestion route, but a limited amount of aflatoxins may also enter through the inhalation route. Aflatoxin exposure assessment may be performed through internal means, i.e., quantification of aflatoxins in blood/plasma/serum, in urine, or in breast milk, or through external means, i.e., estimation of the dietary intake of aflatoxins. In the chapter in hand, the exposure assessment of aflatoxins through external and internal means is discussed in detail.
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Human hair is a slow-degrading nanocomposite biological fiber. In the present work, the surface of human hair has been modified via grafting of poly(methyl methacrylate). The grafting has been done via free radical polymerization using graft from approach. The percent grafting calculated from thermo-gravimetric analysis data was in good agreement with the percent grafting calculated from gravimetric method. The scanning electron microscopy images showed that the hair surface got completely covered when the weight of methyl methacrylate was twice that of human hair in the feed. The ultimate tensile strength and modulus were found to be 1099 MPa and 20 GPa, respectively, when hair was grafted with feed ratio of 2:1 for methyl methacrylate and hair, as compared to 795 MPa and 16 GPa, respectively, for virgin human hair. An improvement in chemical stability was also observed on grafting, under both basic and acidic conditions. The effect of grafting on swelling and adsorption properties has also been studied. For a lower contact time, the removal efficiency was found to be more for anionic dye, methyl orange as compared to cationic dye, methylene blue, but as the contact time increased, the removal efficiency of grafted copolymers for methylene blue increased significantly. The effect of contact time, pH, adsorbent dosage, initial dye concentration on absorption and desorption studies has also been done. The adsorption behavior was studied using isotherm models Langmuir, Freundlich and Temkin model, and adsorption kinetics were investigated using pseudo-first-order and pseudo-second-order model.
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Medical professionals that treat patients with alopecia usually lack knowledge about hair cosmetics. Trichologists focus on hair cycling and growth problems and not on the hair shaft integrity. This may lead to abandon of the use of the prescribed treatment, such as topical minoxidil or to inadequate traumatic grooming habits that may jeopardize hair follicle health. Shampoos, hair dyes, and hair-straightening products may alter hair fiber structure, remove lipids, and elude protein. Hair procedures such as hair dying and straightening have side effects and health concerns, especially for pregnant women or sensitive hair and scalp patients. Hair breakage, follicle traction, frizz, contact dermatitis, and mutagenicity are possible side effects of hair cosmetics misuse. The proper use of hair care products may help to increase patients' adherence to alopecia treatments and avoid health problems related to inadequate application of hair cosmetics and procedures.
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Curvature in mammalian fibers, such as wool and human hair, is an important feature of the functional trait of coat structure – it affects mechanical resilience and thermo-insulation. To examine the relationship between fiber curvature, ultrastructure and protein composition while controlling for fiber diameter, we utilised the progeny of straight-wool domestic sheep mutant rams (crimp mutants) and wild-type ewes. Proteomic and structural results of the resulting mutant/wild-type twin pairs confirmed that straight crimp mutant wool had a normal cuticle and the same cortical protein and ultrastructural building blocks as wild-type (crimpy) fibers but differed in the layout of its cortical cells and in the relative proportions of keratin (K) and keratin associated proteins (KAPs). In the case of the crimp mutants (straight fibers), the orthocortex was distributed in a fragmented, annular ring, with some orthocortical cells near the central medulla, a pattern similar to that of straight hairs from humans and other mammals. Crimp mutant fibers were noted for the reduced abundance of some proteins in the high glycine-tyrosine class normally associated with the orthocortex, specifically the KAP6, KAP7 and KAP8 families, while proteins from the KAP16 and KAP19 were found in increased abundance. In addition to this, the type I keratin, K38, which is also associated with the orthocortex, was also found at lower abundance in the mutant fibers. Conversely, proteins from the ultra-high sulfur class normally associated with the paracortex, specifically the KAP4 and KAP9 families, were found in higher abundance. This article is protected by copyright. All rights reserved.
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Objective The use of conventional microscopy and vibrational spectroscopy in the optical region to investigate the chemical nature of hair fibres on a nanometre scale is frustrated by the diffraction limit of light, prohibiting the spectral elucidation of nanoscale sub-structures that contribute to the bulk properties of hair. The aim of this work is to overcome this limitation and gain unprecedented chemical resolution of cortical cell nanostructure of hair. Methods The hybrid technique of AFM-IR, combining atomic force microscopy with an IR laser, circumvents the diffraction limit of light and achieves nanoscale chemical resolution down to the AFM tip radius. In this work, AFM-IR was employed on ultra-thin microtomed cross-sections of human hair fibres to spectrally distinguish and characterise the specific protein structures and environments within the nanoscale components of cortical cells. Results At first, a topographical and chemical distinction between the macrofibrils and the surrounding intermacrofibillar matrix was achieved based on 2.5x2.5μm maps of cortical cell cross-sections. It was found that the intermacrofibrillar matrix has a large protein content and specific cysteine-related residues, whereas the macrofibrils showed bigger contributions from aliphatic amino acid residues and acidic-/ester-containing species (e.g. lipids). Localised spectra recorded at a spatial resolution of the order of the AFM tip radius enabled the chemical composition of each region to be determined following deconvolution of the Amide-I and Amide-II bands. This provided specific evidence for a greater proportion of α-helices in the macrofibrils and correspondingly larger contributions of β-sheet secondary structures in the intermacrofibrillar matrix, as inferred in earlier studies. Analysis of the parallel and antiparallel β-sheet structures, and of selected dominant amino acid residues, yielded further novel composition and conformation results for both regions. Conclusion In this work, we overcome the diffraction limit of light using atomic force microscopy integrated with IR laser spectroscopy (AFM-IR) to characterise sub-micron features of the hair cortex at ultra-high spatial resolution. The resulting spectral analysis shows clear distinctions in the Amide bands in the macrofibrils and surrounding intermacrofibrillar matrix, yielding novel insight into the molecular structure and intermolecular stabilisation interactions of the constituent proteins within each cortical component.
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Background Damage to hair by UV is relevant to most people, and for many, it is a major source of hair damage. Prevention of UV damage is of high interest to cosmetic companies. Objectives Describe UV damage mechanisms and link these mechanisms to measurable changes in hair protein composition and color changes resulting from breakdown of yellow-colored kynurenines. Test the power of botanical antioxidants, specifically Camellia sinensis (tea) extracts to prevent this protein damage and color change. Link specific phytochemistry of extract samples to hair performance. Methods Camellia sinensis (tea) extracts were analyzed by LC-MS to identify the key composition chemistries. ORAC (Oxygen Radical Antioxidant Capacity) was used to measure ability of the extract to react with a peroxyl radical via a hydrogen abstraction mechanism. Hair protein structural damage was measured by quantification of a biomarker peptide that is specific to UV-induced damage and hair color changes were measured with a spectrophotometer. Results Levels of key phytochemistry in the extracts, specifically the catechins, correlated with prevention of UV-induced protein damage and prevention of color changes due to kynurenine breakdown. Extracts with higher phytochemistry levels also had higher ORAC scores indicating that they were more effective antioxidants. Conclusions Camellia sinensis (tea) extracts can be used as effective protective treatments for hair protection but this efficacy is linked to extract concentrations of key chemistries (catechins).
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Atomic force microscopy integrated with infrared spectroscopy (AFM-IR) has been used to topographically and chemically examine the medulla of human hair fibres with nanometre scale lateral resolution. The mapping of cross-sections of the medulla showed two distinct structural components which were subsequently characterised spectroscopically. One of these components was shown to be closely similar to cortical cell species, consistent with the fibrillar structures found in previous electron microscope (EM) investigations. The other component showed large chemical differences from cortical cells and was assigned to globular vacuole species, also confirming EM observations. Further characterisation of the two components was achieved through spectral deconvolution of the protein amide-I and -II bands. This showed that the vacuoles have a greater proportion of the most thermodynamically stable conformation, namely the antiparallel β-sheet structures. This chimes with the observed lower cysteine concentration, indicating a lower proportion of restrictive disulphide cross-link bonding. Furthermore, the large α-helix presence within the vacuoles points to a loss of matrix-like material as well as significant intermolecular stabilisation of the protein structures. By analysing the carbonyl stretching region, it was established that the fibrillar, cortical cell-like components showed considerable stabilisation from H-bonding interactions, similar to the cortex, involving amino acid side-chains whereas, in contrast, the vacuoles were found to only be stabilised significantly by structural lipids. This article is protected by copyright. All rights reserved
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The composite materials are present in nature since the prehistoric era. Applications of fiber-based composite materials are increasing day by day in our society to overcome the raised environmental and economic concerns. Hence, waste fiber can be utilized as the best resource to develop composites. The present study deals with the impact of hybridization on the mechanical, thermal, and water absorption behavior of hair and coir fiber-based hybrid composites. The compression molding technique was used to develop the hybrid composites with fixed fiber content (15 wt.%) and was also varied the relative weight percentage of hair and coir fibers [(100% HF), (75% HF/25% CF), (50% HF/50% CF), (25% HF/75% CF) and (100% CF)] in reinforcing phase with HDPE composites S 1 , S 2 , S 3 , S 4 , and S 5 , respectively. The composite S 2 was achieved superior mechanical attributes as compared to other hybrid/non-hybrid composites. The composite S 2 was improved the tensile strength 5% and 35.2% more in comparison to composites S 1 and S 5 , respectively. The thermal behavior (TGA, DTG, and DTA) was also influenced by the blending ratio of fibers of composites. The 5% and 50% weight losses of composite S 2 were observed at higher temperature 343.8°C and 465.8°C as compare to other composites, which showed the thermal stability of composites S 2 . SEM analysis was used to investigate the strength of the fiber-matrix interface, which was shown a significant connection between mechanical and thermal behaviors. The crystallinity of hybrid and non-hybrid composites was examined by using the X-ray diffraction (XRD) analyzer and composite S 2 was achieved 326 × 10 ⁻⁹ m crystal size at 21.053° peak position with wavelength 1.5406 × 10 ⁻¹⁰ m for Cu. The water absorption test was used to examine the moisture resistivity of composite materials, which was helpful to increase the applications of materials in humid areas.
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The forensic and medical fields are seeing growing interest in the amino acid and damage biomarker composition of hair, in order to identify adulteration of drug hair testing and for diagnostic purposes. Therefore, there is an increased demand for quick and accurate analytical methods. This study presents the first liquid chromatography-tandem mass spectrometry (LC-MS/MS) assay for the simultaneous quantification of hair amino acids and four damage biomarkers, which also implements an isotopic dilution strategy to improve recovery and precision of the acid hydrolysis-sensitive analytes. The applied strategy enabled a recovery of the hydrolysis-sensitive amino acids between 83-120% (vs. 33-77%, without isotopic dilution) for two different protein standards, and a precision with a relative standard deviation (RSD) between 1.3-7.5% (vs. 9.0-29.4%, without isotopic dilution). All 21 analytes could be measured without interferences by matrix and sample components, thus demonstrating satisfactory selectivity of the method. For spiked samples of hair hydrolyzate, recovery was between 88-120%, whereas precision and intermediate precision were below 10.1%. The high sensitivity of the method made it possible to reduce sample preparation to a 10000-fold dilution of the raw hydrolyzate. The wide linear range displayed by the method allowed the simultaneous quantification of minor (0.3 μmol/g of hair) and major (up to 1000 μmol/g of hair) components of the biological fiber. This method was successfully applied to the analysis of real hair samples submitted to six different treatments. Statistical data analysis by means of t-test and principal component analysis (PCA) showed a clear discrimination of the treated from the untreated hair samples and of the different treatments. Since these hair treatments can interfere with hair drug testing, the method possesses the ability of identifying hair samples with potential for attempted drug test evasion. In addition, lanthionine emerged as a new biomarker for heat damaged hair.
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Objective Dandruff is a common scalp condition that can be improved by regular use of shampoos containing anti-fungal actives. The efficacy of anti-dandruff shampoos can be assessed by measuring scalp flaking, one of the important dandruff symptoms. A randomized, double-blind trial is often used with one of two clinical designs: whole-head parallel design and split-head paired design. We aimed to explore the difference in product differentiation between these two designs using the same two test shampoos and the same scalp flaking assessment method (Total Weighted Head Score Adhered Flakes – TWHS AF). Methods A clinical study was conducted with a 2-3 weeks wash-out phase and a 4-week test phase, consisting of 2 cells: 120 subjects with whole-head parallel design, divided into 2 subgroups (1:1) using on-site controlled washing method (either wash their own hair at a study site, under the instruction of a study supervisor or wash their own hair at home, as per instructions, but without supervision) and 35 subjects with split-head paired design using salon-staff washing method. Both cells employed hair washing at frequency of three times a week, and TWHS AF measurement once a week from the baseline assessment. Results Both designs gave similar differences in TWHS AF between products: 5.6 units (95% CI: 4.1 to 7.0 units) in whole-head design and 5.9 units (95% CI: 4.9 to 6.9 units) in split-head Design. Conclusion Split-head paired design shows a similar ability of detecting product difference as whole-head parallel design, whereas it is a choice of more efficient and more cost-effective, as only a quarter of the subjects are required to demonstrate the efficacy between anti-dandruff shampoos.
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Biopolymers and biocomposites are an exciting class of ubiquitous materials. Interest in these materials has been driven in part by their biocompatibility/biodegradability, sustainability, potentially low-cost, renewability, being environmental benign, among other properties. These fascinating materials come in a range of forms from the DNA and RNA that is essential to life to the cellulose and collagen that mechanically reinforce tissues and as hybrid organic–inorganic composites like teeth. Herein, we summarize some aspects of the two classes of materials biopolymer and biocomposites, exploring specific examples while pointing to potential monomer sources, neoteric post-extraction modification and processing conditions. This lays the foundation to the following more specific chapters while illustrating the breadth of these material classes.
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Hair is a unique biological matrix that adsorbs short-term exposures (e. g., environmental contaminants and personal care products) on its surface and also embeds endogenous metabolites and long-term exposures in its matrix. In this work, we developed an untargeted metabolomics workflow to profile both temporal exposure chemicals and endogenous metabolites in the same hair sample. This analytical workflow begins with the extraction of short-term exposures from hair surfaces through washing. Further development of mechanical homogenization extracts endogenous metabolites and long-term exposures from the cleaned hair. Both solutions of hair wash and hair extract were analyzed using ultra-high-performance liquid chromatography-high-resolution mass spectrometry (UHPLC-HRMS)-based metabolomics for global-scale metabolic profiling. After analysis, raw data were processed using bioinformatic programs recently developed specifically for exposome research. Using optimized experimental conditions, we detected a total of 10,005 and 9,584 metabolic features from hair wash and extraction samples, respectively. Among them, 274 and 276 features can be definitively confirmed by MS ² spectral matching against spectral library, and an additional 3,356 and 3,079 features were tentatively confirmed as biotransformation metabolites. To demonstrate the performance of our hair metabolomics, we collected hair samples from three female volunteers and tested their hair metabolic changes before and after a 2-day exposure exercise. Our results show that 645 features from wash and 89 features from extract were significantly changed from the 2-day exposure. Altogether, this work provides a novel analytical approach to study the hair metabolome and exposome at a global scale, which can be implemented in a wide range of biological applications for a deeper understanding of the impact of environmental and genetic factors on human health.
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This paper reviews developments in industrial colorants as active ingredients of commercial products that rely on oxidative chemistry for the coloration of human hair. After outlining the regulatory challenges faced by the industry, which are shaping the landscape of colorant usage, the most commercially important actives utilised in oxidative hair colorant formulations are surveyed from the perspective of their chemistry and economics. Some developments in the form of recently introduced actives are also described.
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毛髪のハリ・コシ感は, いくつかの物理特性が要因となっているが, 曲げられたときの硬さの他に, ねじられたときの硬さも重要な物理特性である。したがって本研究では, ねじり応力について材料力学的見地から, 剛性率による評価を試みた。レーザー光を利用した毛髪径測定装置により毛髪径を正確に測定した上で, ねじり応力を測定し, 毛髪の剛性率を調べた。また, 物理的にキューティクル層を剥離させたコルテックス部分のみからなる毛髪の剛性率測定を行い, 材料力学的な解析によりキューティクルの剛性率を算出した。ねじりモーメント測定により得られた剛性率から, キューティクルはコルテックスの3.5倍程度硬いことがわかった。また, キューティクルのねじり応力への寄与率は, 全体の約6割に達し, 曲げ応力同様に, ねじり応力の発生はキューティクルが重要な役割を担っていることを見出した。さらに, 剛性率に対するヤング率の比は11.94で, 均質性の物質に比べて非常に大きく, キューティクルおよびコルテックスが, 複雑な内部構造を持った複合材料であるためと考えられた。
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Synopsis The STIFFNESS of COMPONENT FIBERS is known to be important to the behavior of a fiber mass, but measurements are lacking in the cosmetic literature probably because of experimental difficulties with published methods. Recognizing this, we devised a simple method to compare fibers for stiffness. A fiber with a small weight on each end is draped over a wire and the distance ("D") between the vertical legs is measured. Fibers with a wide range of thicknesses clearly showed that values of"D" relate linearly to cross-sectional areas, as expected of "stiffness." This prompted a theoretical study which yielded equations in terms of"D" for calculating, e.g., elastic bending moduli and shapes of hanging fibers. Empirical and theoretical guides are given for selection of wire diameter and fiber weights. The average elastic modulus for bending fibers, assumed round in cross section, is approximately equal to that for stretch-ing the same fibers. Fiber stiffness is affected by humidity and chemical treatments but is relatively unaf-fected by shampoos.
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This book, which provides valuable source material for students and other interested parties, consists of ten chapters. Information is provided on the structure of wool and the role of fibre structure in wool dyeing. The theoretical basis for wool dyeing is analysed and the role of different auxiliaries in wool dyeing is discussed. Pretreatments such as scouring, bleaching and carbonizing are considered and some finishing treatments (insect-resistant finishing, flameproofing) are examined. Suitable dyeing machines are featured and automation is looked at. The dyeing of wool with various dyes (acid, chrome, metal-complex and reactive) is investigated. The book concludes with chapters on the dyeing of wool blends and the printing of wool. Each chapter is written by an expert in the field and has copious references. A subject index is appended.
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Xew evidence of the nature of the bilateral cortex in crimped wool is presented and discussed in relation to the physical and chemical properties of the wool fibre. The origin of the asymmetry in the cortex was studied by cutting cross sections of sheep skin and swelling plucked wool roots. It is shown that the bilateral structure is present before the cortex is keratinized and does not originate from an asymmetrical keratinization as has been suggested. Coarse wools, in which crimp is much less, are shown to possess a radial asymmetry in which the peripheral cortical cells are less accessible to basic dyes and have a higher sulphur content than the central cells. This is related to the difference between the curved follicles from which fine fibres are produced and the straighter follicles producing coarse fibres.
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Letters to the Editor are brief communications intended to provide prompt publication of significant research results and to permit an exchange of views on papers previously published in the Journal. Letters are subject to review, but the authors assume full responsibility for information or opinion expressed.
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Letters to the Editor are brief communications intended to provide prompt publication of significant research results and to permit an exchange of views on papers previously published in the Journal. Letters are subject to review, but the authors assume full responsibility for information or opinion expressed.
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This article describes a simple yet sensitive technique to assess surface damage to hair. It is based on the hypothesis that the damaged hair surface is more susceptible to abrasion/erosion than undamaged hair, and involves shaking hair in water and quantitatively measuring the amount of protein abraded/eroded from the hair using a colorimetric procedure capable of detecting as little as 5 Ixg of protein per mi. With this procedure, we were able to demonstrate significant differences in hair damaged due to bleaching, permanent wave treatments, and Suprox (a diperisophthalic acid based oxidant), and even after extended treatment with different surfactants. Furthermore, hair with exposed cortex was found to be more susceptible to protein loss by surfactants and/or water than hair with intact cuticle.