Modeling Diffusion and Permeation Across the Stratum Corneum Lipid Barrier

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Main Authors: Thomas, Rinto, Prabhakar, Praveen Ranganath, Tobias, Douglas J., von Domaros, Michael
Format: Preprint
Published: 2025
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_version_ 1866908773899042816
author Thomas, Rinto
Prabhakar, Praveen Ranganath
Tobias, Douglas J.
von Domaros, Michael
author_facet Thomas, Rinto
Prabhakar, Praveen Ranganath
Tobias, Douglas J.
von Domaros, Michael
contents Human skin oils are a major sink for ozone in densely occupied indoor environments. Understanding how the resulting volatile and semivolatile organic oxidation products influence indoor air chemistry requires accurate representations not only of their emission into indoor air but also of their transport across the outermost skin barrier, the stratum corneum. Using molecular dynamics simulations, we investigate the passive permeation of acetone, 6-methyl-5-hepten-2-one, and water -- two representative products of skin-oil oxidation and a reference compound -- through a model stratum corneum lipid membrane. We determine position-dependent diffusivities using two complementary analyses based on the same set of simulations and evaluate their accuracy through a propagator analysis. The two approaches provide upper and lower bounds for the true diffusivity, which, when combined with previously reported free-energy profiles, yield permeabilities relevant for modeling macroscopic skin transport. Our results show that permeation is governed primarily by energetic barriers rather than by molecular mobility, and that the predicted transport coefficients vary by about one order of magnitude depending on the chosen diffusivity estimator. These findings provide molecular-level constraints for parameters used in indoor air chemistry models and establish a transferable framework for linking atomistic transport mechanisms to large-scale simulations of human exposure and indoor air quality.
format Preprint
id arxiv_https___arxiv_org_abs_2510_14606
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Modeling Diffusion and Permeation Across the Stratum Corneum Lipid Barrier
Thomas, Rinto
Prabhakar, Praveen Ranganath
Tobias, Douglas J.
von Domaros, Michael
Soft Condensed Matter
Biological Physics
Chemical Physics
Human skin oils are a major sink for ozone in densely occupied indoor environments. Understanding how the resulting volatile and semivolatile organic oxidation products influence indoor air chemistry requires accurate representations not only of their emission into indoor air but also of their transport across the outermost skin barrier, the stratum corneum. Using molecular dynamics simulations, we investigate the passive permeation of acetone, 6-methyl-5-hepten-2-one, and water -- two representative products of skin-oil oxidation and a reference compound -- through a model stratum corneum lipid membrane. We determine position-dependent diffusivities using two complementary analyses based on the same set of simulations and evaluate their accuracy through a propagator analysis. The two approaches provide upper and lower bounds for the true diffusivity, which, when combined with previously reported free-energy profiles, yield permeabilities relevant for modeling macroscopic skin transport. Our results show that permeation is governed primarily by energetic barriers rather than by molecular mobility, and that the predicted transport coefficients vary by about one order of magnitude depending on the chosen diffusivity estimator. These findings provide molecular-level constraints for parameters used in indoor air chemistry models and establish a transferable framework for linking atomistic transport mechanisms to large-scale simulations of human exposure and indoor air quality.
title Modeling Diffusion and Permeation Across the Stratum Corneum Lipid Barrier
topic Soft Condensed Matter
Biological Physics
Chemical Physics
url https://arxiv.org/abs/2510.14606