Biophysical Society Conference | Tahoe 2024

Molecular Biophysics of Membranes

Poster Abstracts

31-POS Board 8 DYNAMICS WITHIN THE LONG PERIODICITY PHASE (LPP) OF THE STRATUM CORNEUM Alexandra Stuer 1 ; Peter D Olmsted 1 ; 1 Georgetown University, Physics, Washington, DC, USA The Human Stratum Corneum (SC) is the protective outermost layer of the epidermis. This primary barrier for permeation comprises corneocytes embedded in a complex lipid matrix with many different lipids in a gel-like state. In dermatology or cosmetics, the performance of a particular active ingredient, "active", requires understanding how and whether the active penetrates the lipid matrix. The complexity (composition and structure) and slow dynamics of the lipid matrix create significant challenges that hinder computational studies to investigate molecule permeation across the skin with atomistic resolution. Here we investigate this phenomenon at atomistic resolution using MD simulations to understand the dynamics during permeation in the lipid region. More specifically, we focus on the mobility of the LPP's lipids as well as of the actives. We try to understand their lateral movement within the layers of the LPP as well as between different layers, a phenomenon described in literature as 'flip-flop' and their re-organisation during long production runs. In addition, we examine diffusion of the active inside the LPP both laterally and along the z direction. We conclude that the heterogeneity of the LPP is strongly affected by the mobility of cholesterol and the free fatty acids between the inner bilayers and the slab. The cholesterol depleted and rigid Ceramide-EOS abundant outer leaflet of the bilayers is relatively immobile both along the xy-plane as well as along the bilayer normal. We propose that cholesterol rich regions affect the mobility of small permeants.

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