Raman Microscopy and Imaging: Applications to Skin Pharmacology and Wound Healing - Emerging Raman Applications and Techniques in Biomedical and Pharmaceutical Fields - page 367

In their initial studies, Tfayli et al. [33] acquired spectra from an Episkin
model. This model is comprised of human adult keratinocytes which produce
stratified epidermis following a 13 h culture period. Raman spectra from this
model were compared with normal human skin. Significant differences were
noted, particularly in spectral features arising from the 850/830 tyr Fermi
doublet (which is sensitive to the H-bonding state of the -OH group [34]) and
in the protein amide III region. Usable spectra were acquired to a depth of
15-20 m.

We have been successful in acquiring useful Raman data from a similar
model. The particular version we have used, EpiDerm TM (full thickness-EFT
200) from MatTEK Corp., also contains epidermal layers and is mitotically
and metabolically active. Raman image planes, 60

μ

μ m( z -direction) × 30 μ m

( x -direction), were constructed from spectra acquired with a step size of 5 m

in each direction. The results of factor analysis in the C-H stretching region
are shown in Fig. 15.5a-c. Two factors with significant scores from the SC of
human and cultured skin are presented in Fig. 15.5. The loadings are shown in
Fig. 15.5a, while score images are presented in Fig. 15.5b and c. Two issues of

μ

Fig. 15.5. Factor analysis results for the C-H stretching region (2800-3050 cm − 1
region) in human skin and in cultured skin model Epiderm TM . Data from human
skin (8 × 12 pixels) and cultured skin (7 × 12 pixels) have been concatenated. Pixels
marked with x's were excluded from the analysis. a Factor loadings for the methylene
stretching region. The dashed vertical line marks 2876 cm − 1 and emphasizes the
shift in frequency between factors 1 and 2. b Scoreplotsforfactor1aredepicted
for human skin in the left set of 8 × 12 pixels and for cultured skin in the right set
of 7 × 12 pixels. c Score plots for factor 2 are depicted for human skin in the left set
of 8 × 12 pixels and for cultured skin in the right set of 7 × 12 pixels