Nanoscale Molecular Characterization of Hair Cuticle Cells Using Integrated Atomic Force Microscopy–Infrared Laser Spectroscopy

Fellows, Alexander P.; Casford, Michael T. L.; Davies, Paul B.

doi:10.1177/0003702820933942

Cited by 21 publications

(16 citation statements)

References 40 publications

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“…After fitting, the band intensity profile of each structure can readily be calculated using the fitted areas. Greater detail on deconvolution procedures can be found elsewhere in the literature as well as in the experimental section 26–28,40 . The intensity profiles based on the deconvoluted spectra in Figure 4 can be found in Figure 5 where three separate spectral regions (Amide‐II, Amide‐I and >1700 cm −1 ) have been separated from each other and normalised independently (the bands >1700 cm −1 are also shown in the Amide‐I profiles for comparison).…”

Section: Resultsmentioning

confidence: 99%

“…Next, further background subtraction was applied to remove underlying broad spectral variations using a spline curve with subsequent smoothing using a 7 pt low‐pass FFT‐filter to remove high‐frequency noise contributions whilst minimising the effects on the underlying (broader) spectral features. (The effectiveness of this protocol to minimise spectral deviations was critically appraised by comparison with the raw spectra, applying the same procedures used previously 26 …”

Section: Methodsmentioning

confidence: 99%

“…The application of this technique to hair and other biological surfaces has provided very significant gains in chemical resolution 19–24 . For example, Marcott et al measured the chemical distribution of structural lipids across the complete cross‐section of the hair fibre, showing the high lipid concentration present in the medulla and CMC, 25 and Fellows et al have applied the technique to show the sub‐structures associated with the cuticle 26 . The current work reports the application of AFM‐IR to the medulla, providing complementary results to electron microscopy for determining its structure, in particular by gaining nanoscale chemical resolution of the different sub‐units.…”

Section: Introductionmentioning

confidence: 99%

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Using hybrid atomic force microscopy and infrared spectroscopy (AFM‐IR) to identify chemical components of the hair medulla on the nanoscale

Fellows

Casford

Davies

2021

Journal of Microscopy

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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.

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Section: Resultsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Using hybrid atomic force microscopy and infrared spectroscopy (AFM‐IR) to identify chemical components of the hair medulla on the nanoscale

Fellows

Casford

Davies

2021

Journal of Microscopy

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“…Applying these hybrid techniques means that the thermal and chemical properties can be obtained and be directly compared to the physical and mechanical structure as observed through traditional AFM measurements [ 17 , 18 , 19 ]. The information obtained from these advanced AFM techniques has proven to be invaluable in many fields, from materials chemistry [ 20 , 21 , 22 ] to biophysics [ 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 ], where chemical mapping of nanoscale features has elucidated structures and processes that would have otherwise escaped detection. In this work, the nanoscale mixing of 50:50 PEEK-PBI blends was investigated for the first time using these novel techniques to gain better insight into its compositional heterogeneity.…”

Section: Introductionmentioning

confidence: 99%

Probing the Nanoscale Heterogeneous Mixing in a High-Performance Polymer Blend

et al. 2022

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The blend of polyetheretherketone (PEEK) and polybenzimidazole (PBI) produces a high-performance blend (PPB) that is a potential replacement material in several industries due to its high temperature stability and desirable tribological properties. Understanding the nanoscale structure and interface of the two domains of the blend is critical for elucidating the origin of these desirable properties. Whilst achieving the physical characterisation of the domain structures is relatively uncomplicated, the elucidation of structures at the interface presents a significant experimental challenge. In this work, we combine atomic force microscopy (AFM) with an IR laser (AFM-IR) and thermal cantilever probes (nanoTA) to gain insights into the chemical heterogeneity and extent of mixing within the blend structure for the first time. The AFM-IR and nanoTA measurements show that domains in the blend are compositionally different from those of the pure PEEK and PBI polymers, with significant variations observed in a transition region several microns wide in proximity to domain boundary. This strongly points to physical mixing of the two components on a molecular scale at the interface. The versatility intrinsic to the combined methodology employed in this work provides nano- and microscale chemical information that can be used to understand the link between properties of different length scales across a wide range of materials.

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“…12 There are also higher 18-MEA concentrations in the cuticle centre than at its edges, which are more more prone to mechanical damage. 13 Moreover, hair from older individuals contains lower 18-MEA levels than younger ones. 14 The outer layers of hair are of particular interest since adsorption of formulation components, as well as lubrication between hair fibres, will largely depend on its surface properties.…”

Section: Introductionmentioning

confidence: 99%

Coarse-grained molecular models of the surface of hair

Weiand

Ewen

Koenig

et al. 2021

Preprint

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We present a coarse-grained molecular model of the surface of human hair, which consists of a lipid monolayer, in the MARTINI framework. Using molecular dynamics simulations, we identify a lipid grafting distance that yields a monolayer thickness consistent with atomistic simulations and experimental measurements of hair surfaces. Coarse-grained models for fully-functionalised, partially damaged, and fully damaged hair surfaces are created by randomly replacing neutral thioesters with anionic sulfonate groups. This mimics the progressive removal of fatty acids from the hair surface by bleaching. We study the structure of the lipid monolayer at different degrees of damage using molecular dynamics simulations in vacuum as well as in polar (water) and non-polar (n-hexadecane) solvents. We also compare the wetting behaviour of water and n-hexadecane on the hair surfaces through contact angle measurements conducted using molecular dynamics simulations and experiments. Our model captures the experimentally-observed transition of the hair surface from hydrophobic (and oleophilic) to hydrophilic (and oleophobic) as the level of bleaching damage increases. By using surfaces with different damage ratios, we obtain contact angles from the simulations that are in good agreement with experiments for both solvents on virgin and bleached human hairs. In both the molecular dynamics simulations and further experiments using biomimetic surfaces, the cosine of the water contact angle increases linearly with the sulfonate group surface coverage. We expect that the proposed systems will be useful for future molecular dynamics simulations of the adsorption and tribological behaviour of hair surfaces.

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Nanoscale Molecular Characterization of Hair Cuticle Cells Using Integrated Atomic Force Microscopy–Infrared Laser Spectroscopy

Cited by 21 publications

References 40 publications

Using hybrid atomic force microscopy and infrared spectroscopy (AFM‐IR) to identify chemical components of the hair medulla on the nanoscale

Using hybrid atomic force microscopy and infrared spectroscopy (AFM‐IR) to identify chemical components of the hair medulla on the nanoscale

Probing the Nanoscale Heterogeneous Mixing in a High-Performance Polymer Blend

Coarse-grained molecular models of the surface of hair

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