Nanomechanical responses of human hair

Samanta, Arnab; Bhattacharya, Manjima; Dalui, Srilzanta; Acharya, Megha; Das, Priyanka; Chanda, Dipak Kr.; Acharya, Saikat; Sivaraman, Sankar Kalidas; Nath, Shekhar; Mandal, Abhijit; Ghosh, Jiten; Mukhopadhyay, Anoop Kumar

doi:10.1016/j.jmbbm.2015.10.010

Cited by 10 publications

(3 citation statements)

References 33 publications

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“…From Figure 7, it was also found that diameter is reduced by approximately 2 μm irrespective of the position as a result of tensile stretching and it could be due to high Poisson's ratio ~0.8 reported for keratin fiber. [21]…”

Section: Resultsmentioning

confidence: 99%

“…The following discussion describes the investigation of structure–property relationship with respect to the tensile properties obtained from hair in order to obtain a better understanding of the heterogeneous and composite structure of hair. Stress–strain plot of a human hair is normally split into three regions,[2122] but the plots are split into four regions in this study [Figures 3 and 4]. Postyield incremental modulus until ~33% strain is reported in the literature[1192324] as the third region, but the fourth region, that is, decrease of postyield modulus between ~33% and 45% strain is not discussed earlier.…”

Section: Discussionmentioning

confidence: 99%

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Effect of scalp position on tensile properties of single hair fibers

2018

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Background:Hair tensile properties play a crucial role in cosmetology regarding functionality and quality. Commonly, scalp positions are subjected to varying magnitudes of environmental and physical stimuli and correspondingly different hair balding patterns are observed.Aim:This study is aimed at comparing the tensile properties of hair from four different scalp positions and quantifying the differences using statistical methods. Further, the second aim is to investigate the structure–property relationship with respect to the tensile properties obtained from hair in order to obtain a better understanding of the heterogeneous and composite structure of hair.Materials and Methods:Hair samples were subjected to tensile testing and position wise data was compared using relative rating and grey relational analysis. Scanning electron microscopy was used to study the fractography of tensile specimens.Results:The modulus, yield stress, maximum stress, and work of elongation were in the range of 2–6 GPa, 60–190 MPa, 130–340 MPa, and 30–100 MJ/m3, respectively. The postyield incremental modulus change at around 33% strain correlated well with fracture features wherein significant macrofibril pullout was observed indicating the fourth region in the stress–strain plot.Conclusion:From the statistical analysis, it was found that there was no significant difference in terms of rating of hair samples from different scalp positions. This may be attributed to the presence of microscopic and nanoscopic structural heterogeneities.

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Section: Resultsmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Effect of scalp position on tensile properties of single hair fibers

2018

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“…The main constituent of hair fibres of relevance to their mass, volume and associated mechanical properties, however, is the cortex, [1,6,11] which is the subject of the present study. As with the two other macroscopic regions, the physical structure of the cortex has been widely studied and consists of long, spindle‐shaped and tightly packed cortical cells embedded in a cell membrane complex (CMC).…”

Section: Introductionmentioning

confidence: 99%

Chemically characterizing the cortical cell nano‐structure of human hair using atomic force microscopy integrated with infrared spectroscopy (AFM‐IR)

Fellows

Casford

Davies

2021

Intern J of Cosmetic Sci

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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 was to overcome this limitation and gain unprecedented chemical resolution of cortical cell nano‐structure 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 characterize 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 2.5 × 2.5 μm 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). Localized 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 characterize 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 stabilization interactions of the constituent proteins within each cortical component.

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Brillouin microscopy for the evaluation of hair micromechanics and effect of bleaching

Correa

Cardinali

Bailey

et al. 2021

Journal of Biophotonics

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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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Nanomechanical responses of human hair

Cited by 10 publications

References 33 publications

Effect of scalp position on tensile properties of single hair fibers

Effect of scalp position on tensile properties of single hair fibers

Chemically characterizing the cortical cell nano‐structure of human hair using atomic force microscopy integrated with infrared spectroscopy (AFM‐IR)

Brillouin microscopy for the evaluation of hair micromechanics and effect of bleaching

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