The relationship between water loss, mechanical stress, and molecular structure of human stratum corneum ex vivo.
Proper hydration of the stratum corneum (SC) is important for maintaining skin's vital functions. Water loss causes development of drying stresses, which can be perceived as 'tightness', and plays an important role in dry skin damage processes. However, molecular structure modifications arising from water loss and the subsequent development of stress has not been established. We investigated the drying stress mechanism by studying, ex vivo, the behaviors of the SC components during water desorption from initially fully hydrated samples using Raman spectroscopy. Simultaneously, we measure the SC mechanical stress with a substrate curvature instrument. Very good correlations of water loss to the mechanical stress of the stratum corneum were obtained, and the latter was found to depend mainly on the unbound water fraction. In addition to that, the water loss is accompanied with an increase of lipids matrix compactness characterized by lower chain freedom, while protein structure showed an increase in amount of α-helices, a decline in α-sheets, and an increase in folding in the tertiary structure of keratin. The drying process of SC involves a complex interplay of water binding, molecular modifications, and mechanical stress. This article provides a better understanding of the molecular mechanism associated to SC mechanics.
Laboratory of analytical chemistry, Analytical Chemistry Group of Paris-Sud (GCAPS-EA4041), Faculty of pharmacy, University of Paris-Sud, 5 rue Jean Baptiste Clement, 92296, Chatenay Malabry, France.
Raoul
R
Vyumvuhore
Ali
A
Tfayli
Krysta
K
Biniek
Hélène
H
Duplan
Alexandre
A
Delalleau
Michel
M
Manfait
Reinhold
R
Dauskardt
Arlette
A
Baillet-Guffroy
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D004817:Epidermis / Q000378:metabolism*; D005260:Female; D006801:Humans; D050356:Lipid Metabolism; D008875:Middle Aged; D011506:Proteins / Q000378:metabolism; D013314:Stress, Mechanical; D014867:Water / Q000378:metabolism*; D055815:Young Adult
D011506:Proteins; D014867:Water
Raman spectroscopy; mechanical stress; skin hydration; stratum corneum