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Raman Spectroscopy Case Study:
Characterising Bleached Hair Damage
Andrew Davies1
Graham Rance1
Nikki Weston2
1Nottingham Nanotechnology and Nanoscience Centre, University of Nottingham 2Advanced Materials Research Group, Faculty of Engineering, University of Nottingham
‘Blondes have more fun….?’
Research Case Study
• Hair is susceptible to changes and damage induced by:
o Mechanical factors:
Heating, blow drying and brushing
o Environmental factors:
Exposure to sunlight and salt water
o Internal factors:
Age and nutrition
o Chemical factors:
Bleaching and colouring treatments
Characterising Hair Damage
PVP – Red, PLGA – Green.
Research Case Study
• Hair is a hierarchical structure.
• Current techniques to evaluate the penetration of chemicals into the internal
volume simply give an average of the whole structure.
• Better characterisation would allow discreet localisation and assessment of
chemical damage.
Kuzuhara, A. Analysis of Structural Change in Keratin Fibers Resulting from Chemical Treatments Using Raman Spectroscopy. 2005. Biopolymers, 77 (6), 335-344
Confocal Raman Spectroscopy
a Research Case Study
• Confocal Raman mapping is an ‘in-situ’, non-destructive chemical analysis and
imaging technique.
• It uses the spontaneous inelastic scattering of light to generate spectra unique to
a material’s molecular composition and state.
• It requires no sample extraction, purification or labelling, and provides molecular
level information about the components in hair with high spectral resolution.
Research Case Study
Raman Mapping
10 μm
10 μm
400 600 800 1000 1200 1400 1600 1800 2000
0
10000
20000
30000
40000
Inte
nsity
Raman Shift / cm-1
1 m
11 m
21 m
41 m
400 600 800 1000 1200 1400 1600 1800 2000
0
10000
20000
30000
40000
50000
60000
70000
80000
Inte
nsity
Raman Shift / cm-1
1 m
11 m
21 m
41 m
• A cross section of bleached hair
was compared to non-bleached
hair.
• Samples were mapped along the
width of the cross section (red
line).
• The graphs opposite show
Raman spectra at various
distances from the outside of
the sample.
• SS (di-sulphide) groups form
cross-linkers in keratin fibres and
contribute to the physical and
mechanical properties of hair.
• The Raman shift for this band
occurs at 430 -550 cm-1
SS
SS
Non-Bleached Hair
Bleached Hair
Research Case Study
Content Tracking
0 10 20 30 40 50 60 70 80
0.00
0.05
0.10
0.15
0.20
0.25
0.30
0.35
0.40
SS
Co
nte
nt
(SS
/CH
)
Distance / m
Non-bleached hair
Bleached hair
Depth profile of the SS content (SS band normalised to the CH band)
Cuticle Cuticle Cortex • Bleaching decreases the SS
content at the cuticle,
destabilising hair structure.
• Bleach does not penetrate
significantly into the centre
of the cortex as SS content
in the centre is the same as
in the non-bleached
sample.
Summary
Research Case Study
• Confocal Raman spectroscopy can provide ‘in-situ’ analysis of chemical damage
across the hierarchical structure of a hair.
• It can be applied to look for subtle changes or differences in material chemistry.
• It has been used to show a reduction in SS bonds caused by bleaching, linked to a
reduction in the mechanical strength of hair.
• The reduction of SS bonds was not observed in the central cortex of the hairs,
suggesting bleach penetration was not sufficient to reach this far.
Further Information
For further information on how Raman spectroscopy, or the
Nottingham Nanotechnology and Nanoscience Centre could help with your applications, systems and designs please contact:
[email protected] +44(0)781 645 3130
ISAC is a University of Nottingham Centre of Excellence in partnership with the National Physical Laboratory
Research Case Study