title: Characterization of stratum corneum molecular dynamics by natural-abundance ¹³C solid-state NMR.
abstract: Despite the enormous potential for pharmaceutical applications, there is still a lack of understanding of the molecular details that can contribute to increased permeability of the stratum corneum (SC). To investigate the influence of hydration and heating on the SC, we record the natural-abundance (13)C signal of SC using polarization transfer solid-state NMR methods. Resonance lines from all major SC components are assigned. Comparison of the signal intensities obtained with the INEPT and CP pulse sequences gives information on the molecular dynamics of SC components. The majority of the lipids are rigid at 32°C, and those lipids co-exist with a small pool of mobile lipids. The ratio between mobile and rigid lipids increases with hydration. An abrupt change of keratin filament dynamics occurs at RH = 80-85%, from completely rigid to a structure with rigid backbone and mobile protruding terminals. Heating has a strong effect on the lipid mobility, but only a weak influence on the keratin filaments. The results provide novel molecular insight into how the SC constituents are affected by hydration and heating, and improve the understanding of enhanced SC permeability, which is associated with elevated temperatures and SC hydration.
authors.affiliation: Division of Physical Chemistry, Center for Chemistry and Chemical Engineering, Lund University, Lund, Sweden. Sebastian.Bjorklund@fkem1.lu.se
authors.forename: Sebastian
authors.initials: S
authors.lastname: Björklund
authors.forename: Agnieszka
authors.initials: A
authors.lastname: Nowacka
authors.forename: Joke A
authors.initials: JA
authors.lastname: Bouwstra
authors.forename: Emma
authors.initials: E
authors.lastname: Sparr
authors.forename: Daniel
authors.initials: D
authors.lastname: Topgaard
mesh_terms: D000818:Animals; D001692:Biological Transport; D002518:Ceramides / Q000737:chemistry* / Q000302:isolation & purification; D003599:Cytoskeleton / Q000737:chemistry*; D004817:Epidermis / Q000737:chemistry* / Q000378:metabolism; D006358:Hot Temperature; D006813:Humidity; D007633:Keratins / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D056004:Molecular Dynamics Simulation; D010539:Permeability; D044367:Phase Transition; D013552:Swine; D014867:Water / Q000737:chemistry* / Q000378:metabolism
chemical_list: D002518:Ceramides; D014867:Water; D007633:Keratins