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Oblitas RLD, Camargo Junior FBD, Magalhães WV, Sá Teixeira FD, Salvadori MC. Characterization of the mechanical properties of the cortex region of human hair fibers by multiparametric atomic force microscopy mapping. Ultramicroscopy 2024; 259:113925. [PMID: 38281370 DOI: 10.1016/j.ultramic.2024.113925] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2023] [Revised: 11/01/2023] [Accepted: 01/11/2024] [Indexed: 01/30/2024]
Abstract
We show the benefit of the use of atomic force microscopy (AFM) in spectroscopy force mode (FV: force volume) for evaluation of the cosmetic active effectiveness in improving the mechanical properties of human hair fibers cortex region. For this, we characterized human hair fibers without and with chemical damage caused by bleaching process. Fiber and resin (embedding material) data were obtained simultaneously in the mapping in order to have the resin data as a reference to ensure a coherent comparison between data from the different fiber groups. Our AFM results, which were evaluated using statistical tests, demonstrated the degradation of fibers after bleaching, corroborating the findings of transmission electron microscopy analysis and the effectiveness of a cosmetic active ingredient in improving the Young's modulus (elastic modulus) (E) of the damaged fibers. We also found a radial decrease in the natural logarithm of Young's modulus ln(E) along the cross-section of the active group fiber, which is compatible with confocal Raman spectroscopy analysis by other authors, demonstrating variation of the active permeation with depth. We note that Young's modulus was also determined by a tensile tester (macro-scale technique), in which it was not possible to obtain statistically significant differences between the groups, evidencing the advantage of the FV-AFM analysis. We also found an increase in ln(E) accompanied by a decrease in maximum adhesion force between tip and sample (negative Pearson correlation coefficient). This result can be explained by the fact that structures composed of hydrophobic components have a higher Young's modulus than structures composed of hydrophilic components.
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Affiliation(s)
| | | | - Wagner Vidal Magalhães
- Departamento de Pesquisa, Desenvolvimento e Inovação, Chemyunion LTDA, Sorocaba, SP, Brazil
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Daniels G, Fraser A, Westgate GE. How different is human hair? A critical appraisal of the reported differences in global hair fibre characteristics and properties towards defining a more relevant framework for hair type classification. Int J Cosmet Sci 2023; 45:50-61. [PMID: 36374002 DOI: 10.1111/ics.12819] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2022] [Revised: 09/15/2022] [Accepted: 09/25/2022] [Indexed: 11/16/2022]
Abstract
This review critically appraises the reported differences in human hair fibre within three related domains of research: hair classification approaches, fibre characteristics and properties. The most common hair classification approach is based on geo-racial origin, defining three main groups: African, Asian and Caucasian hair. This classification does not account sufficiently for the worldwide hair diversity and intergroups variability in curl, shape, size and colour. A global classification into eight curl types has been proposed but may be too complex for reproducibility. Beyond that, hair cross-sectional shape and area have been found to have an inverse relation to curl: straighter fibres are circular with larger cross-sectional area, whilst the curlier fibres are elliptical with smaller cross-sectional area. These geometrical differences have been associated with bilateral vs homogenous distribution of cortical cell in curly vs straight hair respectively. However, there is no sufficient data demonstrating significant differences in hair amino composition, but proteomic studies are reporting associations of some proteins with curly hair. Eumelanin's relative abundance has been reported in all hair colours except for red hair which has a high pheomelanin content. Higher tensile and fatigue strength of straight hair are reported, however, curly hair fragility is attributed to knotting, and crack and flow formations rather than the structural variations. African hair has been found to have the highest level of lipids, whilst the water sorption of Caucasian hair is the highest, and that of Asian hair the lowest. Not all comparative studies clearly report their hair sampling approaches. Therefore, to strengthen the robustness of comparative studies and to facilitate cross-study data comparisons, it is recommended that the following hair defining characteristics are reported in studies: hair cross sectional diameter/area, curl type, hair assembly colour, as well as where possible donor data (age/gender) and sample pooling approach.
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Affiliation(s)
- Gabriela Daniels
- Cosmetic Science Research Group, London College of Fashion, London, UK
| | - Ashiana Fraser
- Cosmetic Science Research Group, London College of Fashion, London, UK
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The information content of tensile tests of human hair (wet) is limited: Variables mainly cluster in just two principal components. J Mech Behav Biomed Mater 2022; 129:105145. [DOI: 10.1016/j.jmbbm.2022.105145] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2021] [Revised: 10/07/2021] [Accepted: 02/26/2022] [Indexed: 01/21/2023]
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Plowman JE, Harland DP, Richena M, Thomas A, Hefer CA, van Koten C, Scobie DR, Grosvenor AJ. Wool fiber curvature is correlated with abundance of K38 and specific keratin-associated proteins. Proteins 2021; 90:973-981. [PMID: 34859500 DOI: 10.1002/prot.26289] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2021] [Revised: 11/08/2021] [Accepted: 11/26/2021] [Indexed: 01/07/2023]
Abstract
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. However, to examine the relationship between fiber curvature, ultrastructure and protein composition fiber diameter variability has to be minimal. To achieve this 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.
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Affiliation(s)
| | | | - Marina Richena
- Proteins and Metabolites, AgResearch, Lincoln, New Zealand
| | - Ancy Thomas
- Proteins and Metabolites, AgResearch, Lincoln, New Zealand
| | | | | | - David R Scobie
- Proteins and Metabolites, AgResearch, Lincoln, New Zealand
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Correa N, Alunni Cardinali M, Bailey M, Fioretto D, Pudney PDA, Palombo F. Brillouin microscopy for the evaluation of hair micromechanics and effect of bleaching. JOURNAL OF BIOPHOTONICS 2021; 14:e202000483. [PMID: 33768666 DOI: 10.1002/jbio.202000483] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/08/2020] [Revised: 02/19/2021] [Accepted: 03/16/2021] [Indexed: 06/12/2023]
Abstract
Brillouin microscopy is a new form of optical elastography and an emerging technique in mechanobiology and biomedical physics. It was applied here to map the viscoelastic properties of human hair and to determine the effect of bleaching on hair properties. For hair samples, longitudinal measurements (i.e. along the fibre axis) revealed peaks at 18.7 and 20.7 GHz at the location of the cuticle and cortex, respectively. For hair treated with a bleaching agent, the frequency shifts for the cuticle and cortex were 19.7 and 21.0 GHz, respectively, suggesting that bleaching increases the cuticle modulus and-to a minor extent-the cortex modulus. These results demonstrate the capability of Brillouin spectroscopy to address questions on micromechanical properties of hair and to validate the effect of applied treatments.
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Affiliation(s)
- Noemi Correa
- School of Physics, University of Exeter, Exeter, UK
| | | | | | - Daniele Fioretto
- Department of Physics and Geology, University of Perugia, Perugia, Italy
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Luengo GS, Fameau AL, Léonforte F, Greaves AJ. Surface science of cosmetic substrates, cleansing actives and formulations. Adv Colloid Interface Sci 2021; 290:102383. [PMID: 33690071 DOI: 10.1016/j.cis.2021.102383] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2020] [Revised: 02/04/2021] [Accepted: 02/06/2021] [Indexed: 12/22/2022]
Abstract
The development of shampoo and cleansing formulations in cosmetics is at a crossroads due to consumer demands for better performing, more natural products and also the strong commitment of cosmetic companies to improve the sustainability of cosmetic products. In order to go beyond traditional formulations, it is of great importance to clearly establish the science behind cleansing technologies and appreciate the specificity of cleansing biological surfaces such as hair and skin. In this review, we present recent advances in our knowledge of the physicochemical properties of the hair surface from both an experimental and a theoretical point of view. We discuss the opportunities and challenges that newer, sustainable formulations bring compared to petroleum-based ingredients. The inevitable evolution towards more bio-based, eco-friendly ingredients and sustainable formulations requires a complete rethink of many well-known physicochemical principles. The pivotal role of digital sciences and modelling in the understanding and conception of new ingredients and formulations is discussed. We describe recent numerical approaches that take into account the specificities of the hair surface in terms of structuration, different methods that study the adsorption of formulation ingredients and finally the success of new data-driven approaches. We conclude with practical examples on current formulation efforts incorporating bio-surfactants, controlling foaming and searching for new rheological properties.
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Ngoepe MN, Cloete E, van den Berg C, Khumalo NP. The evolving mechanical response of curly hair fibres subject to fatigue testing. J Mech Behav Biomed Mater 2021; 118:104394. [PMID: 33691230 DOI: 10.1016/j.jmbbm.2021.104394] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2020] [Revised: 02/05/2021] [Accepted: 02/10/2021] [Indexed: 10/22/2022]
Abstract
Cyclic testing of human hair reveals important details about the behaviour of fibres over many cycles of loading. Phenomena which are observed under static tensile tests give important clues about the form and behaviour of hair fibres, but these do not necessarily remain constant on the inevitable march to failure. In previous work, we demonstrated that curly fibres exhibited a toe-region during tensile tests. The form of curly fibres could be altered by mechanical manipulation but the curl could be recovered upon immersion in water. In this study, where straight and curly fibres are subject to cyclic loading, this characteristic toe-region was shown to be present in the first cycle of loading (for curly fibres). As the number of cycles increased (and the curly fibres progressively became straighter), the stress-strain response of curly fibres started to resemble that of straight fibres. This observation supports our previous hypothesis, which states that the toe-region can be attributed to the presence of a hydrogen bonding mechanism, which is present in curly fibres only, and can be altered by mechanical force. Interestingly, the alteration in load-bearing pattern in curly fibres did not necessarily translate to increased endurance, demonstrating that the relationship between fatigue and strength is a complex one in hair fibres.
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Affiliation(s)
- Malebogo N Ngoepe
- Department of Mechanical Engineering, University of Cape Town, Cape Town, South Africa.
| | - Elsabe Cloete
- Hair and Skin Research Lab, Division of Dermatology, Department of Medicine, Groote Schuur Hospital and University of Cape Town, Cape Town, South Africa
| | - Claire van den Berg
- Hair and Skin Research Lab, Division of Dermatology, Department of Medicine, Groote Schuur Hospital and University of Cape Town, Cape Town, South Africa
| | - Nonhlanhla P Khumalo
- Hair and Skin Research Lab, Division of Dermatology, Department of Medicine, Groote Schuur Hospital and University of Cape Town, Cape Town, South Africa
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Bryson WG, McCormack AC, Plowman JE, Grosvenor AJ, Murphy CJ, Nagase S, Itou T, Koike K. Improved two-dimensional electrophoretic mapping of Japanese human hair proteins; application to curved and straight Japanese human hairs; and protein identification by MALDI MS and MS/MS quadrupole time-of-flight mass spectrometry. Int J Cosmet Sci 2020; 42:346-358. [PMID: 32251525 DOI: 10.1111/ics.12621] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2020] [Accepted: 03/27/2020] [Indexed: 11/29/2022]
Abstract
OBJECTIVES To evaluate improved protein extraction and two-dimensional electrophoresis (2DE) separation methods with Japanese reference human hair (JRH); to determine whether fibre curvature is related to protein composition in curly and straight Japanese women's human hair (JHH) samples; and to identify proteins from JRH 2DE maps and expression differences between curly and straight JHH. METHODS Hair keratin and keratin-associated proteins (KAPs) were extracted intact with dithiothreitol or tris(2-carboxyethyl) phosphine from JRH or from curved or straight JHH. Extracted proteins were isoelectric-focused on first-dimensional pH gradient gel strips, then separated by molecular weight on laboratory-made, second-dimension, large format gels. The software compared protein abundance between duplicate 2DE gels of curved and straight JHH. Thirty-eight proteins from a JRH 2DE gel were enzyme-cleaved for MALDI-TOF-MS analysis to determine peptide composition, and where possible, de novo sequencing gave peptide sequence data. An in-house human hair protein database incorporating ninety-eight annotated protein sequences assisted MS analysis. RESULTS 2DE gels of tris(2-carboxyethyl) phosphine-extracted JRH improved keratin and KAP resolution and number compared to those of dithiothreitol-extracted JRH and published commercially made second-dimensional gels. Silver-stained 2DE gels of the straight or curved JHH sets were remarkably similar. Over-staining to reveal basic proteins caused poor resolution of the major acidic protein classes. Software comparisons of fifty-nine resolved proteins revealed two were significantly different in abundance between curved and straight hairs but in insufficient amounts for MS analysis. MS identified twelve proteins from a JRH CBBG-stained 2DE gel: six type II keratins, three type I keratins and three high sulphur proteins. A further eight were potential conformational isoforms and isoelectric variants of the identified proteins bringing the total to twenty identified or partially identified proteins. CONCLUSION Root-end human hair extraction with tris(2-carboxyethyl) phosphine improves protein resolution and visualizes more proteins on large format 2DE gels. The two minor protein differences between duplicate straight or curved JHH 2DE gels were unlikely to change fibre structure from straight to curved hair. MS results confirmed that multiple isoforms exist of various hair proteins. Low sequence coverage prevented distinction between members in rows of homologous protein spots of similar molecular weight.
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Affiliation(s)
- W G Bryson
- Formerly of Canesis Network Limited, 55 Westlake Drive, Halswell, Christchurch, 8025, New Zealand
| | - A C McCormack
- MYOB NZ Limited, PO Box 2864, 17 Sir William Pickering Drive, Christchurch, 8053, New Zealand
| | - J E Plowman
- Lincoln Research Centre, AgResearch Limited, Private Bag 4749, Christchurch, Canterbury, New Zealand
| | - A J Grosvenor
- Lincoln Research Centre, AgResearch Limited, Private Bag 4749, Christchurch, Canterbury, New Zealand
| | - C J Murphy
- Hutt Central, 3A Epuni St, Lower Hutt, 5011, New Zealand
| | - S Nagase
- Hair Care Products Research Laboratories, Kao Corporation, 2-1-3, Bunka, Sumida, Tokyo, 131-8501, Japan
| | - T Itou
- Hair Care Products Research Laboratories, Kao Corporation, 2-1-3, Bunka, Sumida, Tokyo, 131-8501, Japan
| | - K Koike
- Hair Care Products Research Laboratories, Kao Corporation, 2-1-3, Bunka, Sumida, Tokyo, 131-8501, Japan
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Cloete E, Khumalo NP, Ngoepe MN. The what, why and how of curly hair: a review. Proc Math Phys Eng Sci 2019; 475:20190516. [PMID: 31824224 PMCID: PMC6894537 DOI: 10.1098/rspa.2019.0516] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2019] [Accepted: 10/16/2019] [Indexed: 12/17/2022] Open
Abstract
An attempt to understand and explain a peculiarity that was observed for curly fibres during experimentation revealed disparate literature reporting on several key issues. The phenotypical nature of curly fibres is only accurately understood within the larger scope of hair fibres, which are highly complex biological structures. A brief literature search produced thousands of research items. Besides the large amount of information on the topic, there was also great variability in research focus. From our review, it appeared that the complexity of hair biology, combined with the variety of research subtopics, often results in uncertainty when relating different aspects of investigation. During the literature investigation, we systematically categorized elements of curly hair research into three basic topics: essentially asking why fibres curl, what the curly fibre looks like and how the curly fibre behaves. These categories were subsequently formalized into a curvature fibre model that is composed of successive but distinctive tiers comprising the elements in curly hair research. The purpose of this paper is twofold: namely to present (i) a literature review that explores the different aspects of curly human scalp hair and (ii) the curvature fibre model as a systemized approach to investigating curly hair.
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Affiliation(s)
- Elsabe Cloete
- Hair and Skin Research Lab, Division of Dermatology, Department of Medicine, Groote Schuur Hospital and University of Cape Town, Cape Town, South Africa
| | - Nonhlanhla P. Khumalo
- Hair and Skin Research Lab, Division of Dermatology, Department of Medicine, Groote Schuur Hospital and University of Cape Town, Cape Town, South Africa
| | - Malebogo N. Ngoepe
- Department of Mechanical Engineering, University of Cape Town, Cape Town, South Africa
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