  Many questions concerning the biophysical and physiological properties of
skin are still open. Skin aging, permeability, dermal absorption, hydration and
drug transdermal delivery, are few examples of processes with its underlying
mechanisms unveiled. In this work we present a first-principles density
functional quantum atomistic model for single layer stratum corneum (SC) in
order to contribute to unveil the molecular interactions behind the skin
properties at this scale. The molecular structure of SC was modeled by an
archetype of its hygroscopic proteic portion inside of the corneocytes, the
natural moisturizing factor (NMF), coupled to glycerol molecules which
represent the lipid fraction of SC. The vibrational spectra was calculated and
compared to Fourier-Transform Infrared Absorption spectroscopy (FTIR)
experimental data obtained on animal model of SC. We noticed that bands in the
fingerprint region (800-1800 cm$^{-1}$) were correctly assigned. Moreover, our
calculations revealed the existence of two coupled vibration between hydroxyl
group of lipid and NMF methylene (1120 and 1160 cm$^{-1}$), which are of
special interest since they probe the lipid-amino acid coupling. The model was
also able to predict the shear modulus of dry SC in excellent agreement with
the reported value on literature. Others physical/chemical properties could be
calculated exploring the chemical accuracy and molecular resolution of our
model. Research in dermatology, cosmetology, and biomedical engineering in the
specific topics of drug delivery and/or mechanical properties of skin are
examples of fields that would potentially take advantage of our approach.
