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Effects of oxidative treatments on human hair keratin films
Abstract
The effects of hydrogen peroxide and commercial bleach on hair and human hair keratin films were examined by protein solubility, scanning electron microscopy (SEM), immunofluorescence microscopy, immunoblotting, and Fourier-transform infrared spectroscopy. Protein solubility in solutions containing urea decreased when the keratin films were treated with hydrogen peroxide or bleach. Oxidative treatments promoted the urea-dependent morphological change by turning films from opaque to transparent in appearance. Immunofluorescence microscopy and immunoblotting showed that the oxidation of amino acids and proteins occurred due to the oxidative treatments, and such occurrence was more evident in the bleach-treated films than in the hydrogen peroxide-treated films. Compared with hair samples, the formation of cysteic acid was more clearly observed in the keratin films after the oxidative treatments.
... Keratin can be extracted from a variety of sources such as human hair [7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26] and nails, 12 chicken feathers, 27 and wool, [28][29][30][31][32][33][34] and fabricated into thin films. Keratin films have been principally studied for their use as biomaterials, [7][8][9][10]12,15,[20][21][22][23][24][25][27][28][29][30][31][32][33][34][35][36][37][38] but recently human hair keratin films have been explored as substrates for gauging hair damage. ...
... Keratin films have been principally studied for their use as biomaterials, [7][8][9][10]12,15,[20][21][22][23][24][25][27][28][29][30][31][32][33][34][35][36][37][38] but recently human hair keratin films have been explored as substrates for gauging hair damage. 11,13,14,19,26,39 There are several potential advantages to using human hair keratin films in lieu of hair fibres for experimental (product design) studies. Often, 1-2 g hair samples are used for a single experiment. ...
... The acetic acid aided in disulphide bond reformation and protein aggregation. 13 Recently, Fujii et al. 18,19 demonstrated that the use of 20-30 mmol/l and 50-125 mmol/l acetic acid was effective in producing opaque and translucent films, respectively. Figure S1 is a schematic representation of the keratin film formation process. ...
The technology for generating high quality keratin films has recently advanced and led to their implementation in a variety of applications. As an initial step toward investigating the films as a screening tool for predicting the efficacy of potential hair dyes, CI Acid Orange 7 was applied to a set of opaque and translucent films. Overlaid time‐of‐flight secondary ion mass spectrometry images arising from protein and dye fragments revealed that dye uniformly penetrated both film types. Results also showed that the relative concentration of dye in each film complemented outcomes from ultraviolet‐visible analysis and revealed that the translucent film contained a higher dye concentration. Scanning electron microscopy analysis of film morphology suggested that the observed difference was due to the higher porosity of the opaque film, which facilitated dye desorption during the rinsing step. Consequently, the translucent film was judged to be a better substrate for screening potential new hair dyes.
... Cystine is present at a much higher concentration than cysteine in the plasma, whereas cystine is converted intracellularly to cysteine [32,33]. The cys content of KER was mainly in the form of cysteic acid; formation of cysteic acid in keratin has been observed after oxidative treatment [34]. L-cysteine is not an essential amino acid in the rat, which can synthesise it from L-methionine via a trans-sulphuration pathway, but when it is present in the diet, it can spare the L-methionine requirement [35]. ...
... In both KER + CAS and CAS control groups, liver taurine concentrations were within the normal range for male rats [40]; however, liver taurine was significantly higher in KER + CAS rats compared to CAS control, and significantly lower in PEA rats compared to CAS control. As cysteic acid has been shown to be metabolised to taurine in the rat [34], it is likely that the high concentration of cysteic acid in the KER protein effected the observed increase in liver taurine concentrations. Taurine and cys-containing compounds have hepatoprotective effects [41][42][43].These findings confirmed that the PEA diet was insufficient in SAA, while the KER + CAS diet was superior to the CAS control diet. ...
Poultry feathers, consisting largely of keratin, are a low-value product of the poultry industry. The safety and digestibility of a dietary protein produced from keratin (KER) was compared to a cysteine-supplemented casein-based diet in a growing rat model for four weeks. KER proved to be an effective substitute for casein at 50% of the total dietary protein, with no changes in the rats’ food intake, weight gain, organ weight, bone mineral density, white blood cell counts, liver glutathione, or blood glutathione. Inclusion of KER in the diet reduced total protein digestibility from 94% to 86% but significantly increased total dietary cysteine uptake and subsequent liver taurine levels. The KER diet also significantly increased caecum weight and significantly decreased fat digestibility, resulting in a lower proportion of body fat, and induced a significant increase in blood haemoglobin. KER is therefore a safe and suitable protein substitute for casein, and the cysteic acid in keratin is metabolised to maintain normal liver and blood glutathione levels.
... The modifications above were employed based on the following reports:, 30 who studied human hair treated with H 2 O 2 and found out that protein solubility decreased when the keratin films were treated with hydrogen peroxide; moreover, they observed the oxidation of amino acids and proteins due to the oxidative treatments, with the formation of cysteic acid., 31 who treated chicken feathers with H 2 O 2, found that the treatment promoted keratin bisulfides' oxidation into sulfonate groups. The modification with H 2 SO 4 is based on the results of, 32 ,and 33 who found out good results by using sulfuric acid for the hydrolysis of protein in feathers, being more efficient than nitric and phosphoric acid for obtaining a large number of peptides producing almost complete hydrolysis of feathers [depending on the concentration). ...
The main objective was to develop renewable materials derived from chicken feathers to remove chromium in the wastewater of the electroplating industry. The chicken feather biosorbents (BCF) were modified with H2O2, H2SO4, and NaOH 0.1 mol L−1 solutions, generating CF.H2O2, CF.H2SO4, and CF.NaOH. These were characterized through chemical analysis, FT-IR, XDR, and TG. Subsequently, studies aiming to remove Cr(total) were carried out, which evaluated the developed materials’ performance. The CF materials have surface functional groups such as S = O, C-O, C-N, COO-, -NO2, C = C, N-H, C-H, and O-H, interacting with Cr ions in solution. The XRD analysis indicates two kinds of crystal structure, α-helix, and β-sheet, from keratins. The estimate optimal conditions for Cr(total) removal occurs at pH 7.50 (for BCF), 7.00 (for CF.H2O2), 6.50 (for CF.H2SO4) and 7.00 (for CF.NaOH), and by using 4.0 g L−1. The best fit was obtained for pseudo-second order; however, the good results for pseudo-first order might indicate a combination of physical and chemical adsorption. The results from thermodynamics evaluations indicate that the removal of Cr(total) is endothermic for CF.H2O2, CF.H2SO4, and CF.NaOH while is exothermic for BCF.
... In contrast to hair of which characteristics easily vary due to individual differences, the keratin film is effective at improving testing precision and reproducibility In addition to the light exposure test, because the keratin film can reproduce the same changes occurring to the hair protein when subjected to bleaching, perm applications, and the like with high sensitivity, it has been actively utilized to develop materials to confirm changes due to hair damages and minimize the damages. With respect to the impact of oxidation from bleach treatments, even with a slight oxidation condition, which could not be confirmed with hair samples, cysteic acid could be detected with FT-IR [13]. Moreover, in applications in perm agent treatments, we confirmed that proteins that are eluted during a reducing agent treatment are keratin-related proteins, which suggests that they are indicators of damage due to perm agents [14]. ...
A variety of natural polymers such as biologically derived proteins, lipids, and functional polysaccharides are blended as materials for functionality and safety in beauty products. Of these natural polymers, we developed the polysaccharide curdlan (β-1, 3-glucan), which forms an irreversible gel through heating at a certain temperature or higher, as a beauty product material that has a hairstyling function of memorizing a hairstyle when heat from a dryer is applied. We also used a curdlan gel obtained by heating and appropriately molding this curdlan as a substitute for conductive adhesive paste that is generally used to secure electrodes for measuring brain waves to the scalp. On the other hand, in the research and development of beauty products, efforts are also actively underway to develop a technique to objectively evaluate the effectiveness and functionality of beauty products. We also realized a simple, high precision method that uses keratin film fabricated from a protein solution extracted from hair to detect initial hair degradation, which is ordinarily difficult to measure with high precision due to variations such as individual differences and damage history.
... The change in the protein structure was further investigated by the Bradford Protein Assay which examined the amount of solubilized protein which is extracted using the Shindai method (Ernst & Zor, 2010;Nakamura et al., 2002). The Bradford Protein Assay is used widely for estimating the amount of total protein in a proteinous substrate such as human hair and animal fibers (Fujii et al., 2012;Rane & Barve, 2010). The estimation of protein is based upon the binding of the Coomassie brilliant blue dye with the protein which is most prominently absorbed at 595 nm (Ernst & Zor, 2010). ...
Mongolian cashmere sliver, yarn, and fabric were dyed and bleached with a solution of ascorbic acid and iron sulfate at 70^{\circ}C, and then dyed using natural indigo powder at the dyeing temperature of 25^{\circ}C to 90^{\circ}C for 15-90 minutes using the IR dyeing machine. K/S values of bleached samples decreased significantly when dyed above 70^{\circ}C dyeing temperature for a longer dyeing time. Bleached cashmere fabric showed a greater loss of tensile strength than unbleached cashmere fabric, even when the samples were dyed at 40^{\circ}C. With a higher dyeing temperature, yarns lost fullness, became thinner, and the pores between the yarns were enlarged. The x-ray diffraction pattern exhibited a prominent increase in crystallinity and the protein assay indicated a loss of protein in the bleached sample dyed at 90^{\circ}C. Thinning of scales, fractured or raised tip of scales, and roughness on the entire surface of the fiber were also observed. The results indicate that bleaching and high temperature dyeing cause a serious damage to cashmere fibers. In addition, bleaching and high temperature dyeing cause significant fiber damage. Natural indigo dyeing using low temperature dyeing is recommended to produce blue color cashmere.
... Scanning electron microscopy (SEM) has been performed on hair sampled from living subjects damaged by aesthetic treatments [8,9], on damaged and fractured hair [10], as well as on archaeological mummies [11]. At present, however, very little information is available on hair modifications caused by environmental factors [12], such as insects and fungi which may colonize and feed on bodies during decomposition [13]: observations of modifications on hair caused by the feeding activities of moths (Tineola bisselliella (Hummel, 1823), Trichophaga tapetzella (Linnaeus, 1758), Tinea pellionella (Linnaeus, 1758), Lepidoptera, Tineidae, and Hofmannophila pseudospretella, (Stainton, 1849), and Lepidoptera, Oecophorinae) [14] and beetles (Anthrenus sp. ...
Purpose:
The analysis of hair can provide useful information for the correct evaluation of forensic cases, but studies of trauma on hair are extremely rare. Hair may present lesions caused by traumatic events or by animals: in fact, signs of sharp force weapons on hair may provide important information for the reconstruction of the manner of death, and, for example, may suggest fetishist practice. This study stemmed from a judicial case where it was fundamental to distinguish between sharp force lesions and insect activity on hair.
Methods:
In order to highlight differences between sharp force lesions and insect feeding activity, different experiments were performed with high power microscopy: hair samples were subjected to several lesions by blunt and sharp force trauma; then samples were used as pabulum for two taxa of insects: the common clothes moth (Tineola bisselliella Lepidoptera, Tineidae) and the carpet beetle (Anthrenus sp., Coleoptera, Dermestidae). Hairs were examined from a macroscopic and microscopic point of view by stereomicroscopy and scanning electron microscopy (SEM): the morphological characteristics of the lesions obtained from the different experimental samples were compared.
Results:
Results show that sharp force trauma produces lesions with regular edges, whereas insects leave concave lesions caused by their "gnawing" activity. These two types of lesions are easily distinguishable from breaking and tearing using SEM.
Conclusions:
This study demonstrates that insect activity leaves very specific indications on hair and sheds some light on different hair lesions that may be found in forensic cases.
The dyeing and fading of semi-permanent hair colors were examined using transparent human hair keratin film. Among four kinds of commercial semi-permanent hair colors, the translucent keratin film was significantly dyed with three products. The coloring was dependent on dyeing time and increasing dyeing number, and the latter was important to gain deeper dyeing. When the film was dyed by two different products and analyzed by a spectrophotometer, spectra of the average absorbance were independent of the dyeing order. Compared with the dyeing of oxidative hair color products, no significant formation of cysteic acid was found in the films dyed with semi-permanent hair colors. When the dyed films were immersed in distilled water and tap water, the fading by tap water was faster than that by distilled water. The addition of EDTA to the tap water suppressed the color fading, whereas the addition of CaCl2 to distilled water caused the fading, indicating that metal ions will be closely related to the fading by water. The fading was also observed when the dyed films were exposed to artificial light (300-2500 nm) using a solar simulator. The fading was conveniently measured and the rate of change indicated the difference between the products. These results suggest that translucent keratin film will be useful to develop damage-free, anti-washout, and less-photofading hair color products.
The proteins in human hair consist primarily of microfibrillar keratins with a molecular mass of 40-65 kDa and keratin-associated proteins (KAPs) with a molecular mass of 6-30 kDa, according to the results obtained from sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). Because an effective purification procedure of KAPs has not been established, little is known about the protein chemistry of KAPs as compared with that of keratin. When hair samples were incubated in the Shindai solution containing alcohols such as methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, and 2-methyl-1-propanol, the extraction of KAPs was enhanced, while extraction of keratin was suppressed. Using ethanol, we established a selective purification procedure for KAPs and keratin. According to Tricine/SDS-PAGE, the KAPs fraction contained six polypeptides with molecular masses of 3.5, 4.4, 5.2, 7.8, 15, and 28 kDa. The keratin fraction contained two polypeptides with molecular masses of 45 and 67 kDa and was free of low-molecular-weight components. The amino acid compositions of the KAPs and keratin fractions were mostly in agreement with the values found in the literature. The recoveries of the KAPs and keratin fractions from the hair samples were approximately 10 and 50%, respectively. Scanning electron microscopy (SEM) showed that hair samples retained fine fibrous structures in the cortex after extracting the KAPs and that the additional extraction of keratin caused the fibrous structures to disappear. These results indicated that KAPs may function by surrounding the fibrous structures and supporting the keratin fibers in the cortex. In this study, we propose a novel and convenient isolation procedure for KAPs and keratin from human hair.
We have become aware of UV protection for skin in recent years. However we haven't been aware of it for hair. Hair is easily exposed to UV, because hair is different from skin in that it doesn't suffer such reactions such as a hot flash or a slight redness. In fact hair is damaged by sunlight slightly in daily life, and this leads to perceptible heavy damage such as split hair ends, broken hairs and a dry feeling. To maintain and preserve non-damaged healthy hair, we believe it is necessary to protect hair from UV exposure in daily life, and prevent the accumulation of damage to hair. In this paper we discuss hair damage due to UV irradiation, a detection method for early stage modification and technology for protecting hair from UV exposure in daily life.
We have developed a preparation method of a translucent keratin film in addition to a nonanslucent film. The translucent keratin film was light brown and its surface was smooth by SEM observation. both films were treated with oxidative hair color reagents (dark brown and light brown), color deposit of translucent film was higher than that of the non-translucent film. Interestingly, the color can be easily ured from an absorption spectrum with a spectrophotometer. Thus, we dyed the translucent keratin film the dark brown color reagent under various conditions and analyzed the color deposit by a as a model system. The coloring was depending on the film thickness, the dyeing time, the ncubation temperature, and at lower pH. The formation of cysteic acid was significantly detected, similar to non-translucent keratin film. When the dyed films were immersed in distilled water and tap water, the discoloration by tap water was ster than that by distilled water. The addition of 0.5 mM CaCl2 to distilled water could induce the color fading. discoloration was also found when the dyed film was exposed to artificial light using a solar simulator. irradiation induced not only a significantly decrease of absorption around the 500 nm but also an increase absorption around the 400 nm, indicating a different hue of the dyed film. The translucent keratin film will be useful to evaluate conveniently the dyeing and discoloration of by dative hair dye reagents
Most of the dermatophyte species have the ability to perforate hair structure and consume its contents of keratin through secretion of keratinase enzyme. Two clinical isolated species of dermatophytes were diagnosed as Trichophyton mentagrophytes var. granulosum and Trichophyton verrucosum. To determine the perforation ability, the isolated fungi were incubated with the hair of four different animals (rabbit, rat, cow and cat) and human hairs with three different colours (black, albino and bleached yellow) for different periods. Variable perforating ability of T. mentagrophytes was shown in rat hair and all types of human hair after 15 days, while other mammalian hairs exhibited resistance to this fungal activity. On the other hand, T. verrucosum was revealed a slow perforating ability, which needed a long time (60 days) for most of tested hairs. Perforation of human black hair could be considered a diagnostic test for differentiation between T. mentagrophytes and T. verrucosum. In conclusion, the treated or untreated human hair was considered more suitable to use as a source of keratin for the growth of dermatophytes than animal hairs. The human black hair was a best type of hair to use in the perforating test for differentiation between T. mentagrophytes and T. verrucosum.
Human hair keratin film has been used as an alternative to hair samples to evaluate various damages. This film consisted of keratin and keratin-associated proteins (KAPs). The function of KAPs on the molecular constitution of hair and keratin film remains unclear. Recently, we have developed a selective isolation method for keratin and KAPs from human hair. In this study, we proposed a novel keratin film lacking KAPs using the Pre-cast method. The concentration of acetic acid in the casting solution of hair protein solution was higher than that in hair protein solution lacking KAPs. The morphology and chemical properties of the KAPs free keratin film were compared with those of conventional and high acetic acid keratin films containing KAPs. The KAPs free and high acetic acid films were beige and semitransparent in appearance, whereas the conventional film was white and opaque appearance. SEM observation indicated the KAPs free film was made up reticular structure and the surface was covered by small particles around 1 μm in diameter. When these films were stained with oxidative hair color reagents, color deposits of the KAPs free and high acetic acid films were higher than that of the conventional film. Compared with hair sample, the formation of cysteic acid was significantly prompt in these keratin films. The amount of the KAPs free film was slightly lower than those of the conventional and high acetic acid keratin films. When reductive permanent reagent containing thioglycolic acid was added to these keratin films, the optical transmittance was decreased. And the decrease was recovered by oxidative permanent processing. The film formation technology will be useful to evaluate various functions under which keratin and KAPs were classified.
Keratin film prepared from human hair samples can be considered a model which represents an average human hair. In this study, the investigations were focused on whether the keratin film can withstand physical and chemical stimulations such as ultraviolet (UV), bleach, perm, and thermal treatments or not. Obtained data indicated that keratin film responded to such hair damage factors in the similar manner as hair, and responses of keratin film were significantly higher than those of hair. Keratin film can be used as a substitute device for human hair, to accurately evaluate hair damage for the development of hair care related products.
A protein determination method which involves the binding of Coomassie Brilliant Blue G-250 to protein is described. The binding of the dye to protein causes a shift in the absorption maximum of the dye from 465 to 595 nm, and it is the increase in absorption at 595 nm which is monitored. This assay is very reproducible and rapid with the dye binding process virtually complete in approximately 2 min with good color stability for 1 hr. There is little or no interference from cations such as sodium or potassium nor from carbohydrates such as sucrose. A small amount of color is developed in the presence of strongly alkaline buffering agents, but the assay may be run accurately by the use of proper buffer controls. The only components found to give excessive interfering color in the assay are relatively large amounts of detergents such as sodium dodecyl sulfate, Triton X-100, and commercial glassware detergents. Interference by small amounts of detergent may be eliminated by the use of proper controls.
The effect of hair dyes, i.e., temporary, semi-permanent, or permanent hair dyes, or hair bleach on the isoelectric focusing (IEF) hair protein patterns was studied. A permanent hair dye (metallic, alkaline oxidative, or acidic oxidative) and hair bleach induced changes in the IEF hair protein patterns and in the intensity of hair protein bands. The changes in the IEF patterns, caused by the alkaline oxidative dye or the bleach, are considered to result from the combined effect of an alkaline agent and an oxidative agent in the alkaline oxidative dye and in the hair bleach.
Using an improved method of gel electrophoresis, many hitherto unknown
proteins have been found in bacteriophage T4 and some of these have been
identified with specific gene products. Four major components of the
head are cleaved during the process of assembly, apparently after the
precursor proteins have assembled into some large intermediate
structure.
We developed a rapid and convenient extraction procedure of human hair proteins to examine their biochemical properties in detail. This procedure is based upon the fact that the combination of thiourea and urea in the presence of a reductant can effectively remove proteins from the cortex part of human hair. The extracted fraction mainly consisted of hard alpha-keratins with molecular masses of 40-60 kDa, matrix proteins with 12-18kDa, and minor components with 110-115kDa and 125-135kDa on sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). The protein phosphorylation in human hair was investigated by immunoblotting with antibodies against phosphoserine, phosphothreonine and phosphotyrosine. We found serine phosphorylation in alpha-keratins and matrix proteins and threonine phosphorylation in alpha-keratins. The extraction was also found to be effective when wool, chicken feathers, rat hair and human nails were used as starting materials.
Comparative two-dimensional electrophoretic (2-DE) studies were performed over a time-course to examine the effect of oxidation or alkylation on the separation of wool keratin proteins. The effect of oxidation was followed by treating scoured wool fibres with increasing levels of hydrogen peroxide, ranging from 0-12 g/L, using conditions mimicking the industrial wool bleaching process. Peroxide treatment was found to have only a minor effect on the 2-DE separation of the intermediate filament protein (IFP) class. Conversely, peroxide treatment of the 24-28 kDa high sulphur protein (HSP) class, which contains up to 40 cysteine residues per protein, resulted in the gradual disappearance of the major HSP spots correlated with the appearance of a few discrete spots at lower isoelectric point (pI). This suggested that only a few specific cysteine residues were being oxidized to cysteic acid by treatment with hydrogen peroxide. Peroxide treatment also appeared to have affected a discrete number of cysteine residues among proteins in the high glycine-tyrosine protein (HGTP) class, reducing the intensity of the high pI spots, while correspondingly increasing the intensity of those at lower pI. In a separate study, wool proteins were alkylated with iodoacetamide (1 M, pH 8) for periods ranging from 10 min to 48 h. In contrast to treatment with peroxide, the pI values of the HSP spots were unaffected by alkylation, irrespective of the length of this treatment. Alkylation resulted in a shift to lower pI and a loss of resolution of individual spots in the Type I and II IFP trains, to the extent that after 24 h alkylation individual spots in these trains merged. In addition after 1 h the intensity of the high pI Type II IFPs decreased until they were no longer visible on the 2-DE map after 24 h. Similarly as alkylation time increased, the major, high pI HGTP spots decreased in intensity. In unison with their decrease, some of the lower pI spots increased in intensity, while new spots appeared at more acidic pIs. Mass spectral studies indicated that cysteine alkylation was relatively fast, with 70-95% of the cysteines in the keratin proteins being alkylated within the first 10 min, while in the case of the HGTPs there was evidence for noncysteine alkylation occurring within this period. Alkylation of proteins for periods of up to 6 h prior to electrofocusing is being promoted as a better alternative to the current 2-DE protocol of the inclusion of a reductant in the immobilized pH gradient rehydration solution. This study has clearly demonstrated that long alkylation times do not suit all protein types or classes.
We have developed a novel method of extracting proteins from human hair in the absence of detergent called the "Shindai Method". Using the protein solution consisting of hard alpha-keratins and matrix proteins prepared by this method, we developed two procedures for preparing hair protein films. The protein solution was mixed with trichloroacetic acid (TCA), perchloric acid (PCA) or guanidine-HCl (GHA), and then exposed in distilled water. Light brown aggregates immediately formed (Pre-cast method). The other method is based on the same characteristics of the hair proteins to form protein aggregates. The protein was directly exposed to the solution containing TCA, PCA, GHA, HCl, H(2)SO(4) or acetate buffer (Post-cast method). The maximum yield was greater than 70%. These protein films were water-insoluble and mainly made up of alpha-keratins. Scanning electron micrographs showed that the fine surface of the protein films was composed of particles, filaments, and porous structures and the constitution was dependent on the preparation procedure used. When porcine intestine alkaline phosphatase (ALP) was mixed with the hair protein solution in a Post-cast method using acetate buffer (pH 5), ALP was incorporated into the alpha-keratin films. The activity retained in the protein film was approximately 8% of the original level. The biochemical properties of the ALP activity in the film were similar to those of the native enzyme.
We have developed novel procedures for preparing human hair protein films (Pre-cast and Post-cast methods). The light brown films obtained by these procedures were too fragile to apply to human skin. We found that the film was also formed when the hair proteins extracted by the Shindai method were directly exposed to the solution containing MgCl(2), CaCl(2), NaCl or KCl. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) showed that the surface of the novel protein films was smooth. The protein films mainly consist of alpha-keratins and matrix proteins. After drying, the films became translucent and flexible during folding, indicating the possibility that these protein films are useful for practical applications. Hence, we prepared gauze-coated protein films to reinforce their physical strength and tested the influence on human skin. A patch test showed that the protein films made from individual and multiple human hairs only slightly stimulated rubor and anthema, itching, drying, smarting and pain on the contact area of arm skin.
To investigate the influence of bleaching treatments on keratin fibers, the structure of cross-sections at various depths of bleached human hair (black and white human hair) was directly analyzed without isolating the cuticle and cortex, using Raman spectroscopy. The S-S band intensity existing from the cuticle region to the center of cortex region of virgin white human hair decreased, while the S-O band intensity at 1040 cm(-1), assigned to cysteic acid, increased by performing the bleaching treatment. Especially, the S-O band intensity of the cuticle region increased remarkably compared with that of the cortex region. Also, the amide III (unordered) band intensity in the cortex region increased, indicating that some of the proteins existing throughout the cortex region changed to the random coil form. Moreover, it has been found that the S-S band intensity existing from the cuticle region to the center of the cortex region of the virgin black human hair decreased remarkably, while the S-O band intensity increased significantly compared with that of the virgin white human hair by performing the bleaching treatment. From these experiments, we concluded that the melanin granules including metal ions act as a decomposition accelerator for the oxidizing agent, thereby leading to a higher level of disulfide (-SS-) group cleavage in the black human hair compared with that of the white human hair.