Partition of sodium dodecyl sulfate into stratum corneum lipid liposomes

Abstract

Synthetic detergents produce deleterious effects on human skin as the result of being taken up by the stratum corneum (SC). The present study aimed to determine to what extent a typical detergent enters the SC lipid lamellae, and what effect this might have on the physical properties of the lipids. These effects were studied in large unilamellar liposomes prepared from SC lipids (50% by weight of epidermal ceramides, 28% cholesterol, 17% free fatty acids, and 5% cholesteryl sulfate) by extrusion through successive polycarbonate filters of decreasing pore size, finally 400 nm. Freeze-fracture electron microscopy and light-scattering particle size analysis indicated a uniform liposome diameter averaging 230 nm. Partitioning of sodium dodecyl sulfate (SDS) into the lipid phase from aqueous buffer solutions was measured using the SC lipid liposomes and [U-14C]SDS. The partition coefficient was 416, 450, and 588 at pH 8.5 and 524, 507, and 807 at pH 7 for three different concentrations (0.1%, 0.02%, and 0.004%) of SDS. This high degree of partitioning into the liposomes is consistent with the high level of SDS partitioning seen in full SC. At the maximum, the SDS represented 18% of the liposomal lipids. Preparation of stable liposomes from SC lipids to which 10% or 20% of SDS had been added confirmed the ability of the liposomes to survive these high concentrations of surfactant. The permeability of the liposomes was enhanced as a result of SDS partitioning into the bilayers, as measured by the increased release of trapped [U-14C]glucose from these vesicles, and by their increased permeability to water in osmotic shock experiments.(ABSTRACT TRUNCATED AT 250 WORDS)

Influence of cholesterol on the structure of stratum corneum lipid model membrane

“…In order to carry out these measurements successfully, it was important to prepare stable unilamellar vesicles of a SC lipid model system. The composition was chosen according to previous studies showing that to create stable ULVs, high pH of the environment is required [18,39]. Unlike pH values close to human skin, at pH 9, the charged components (palmitic acid and CS in the present system) are mainly ionized [40].…”

How Do Dermatological Vehicles Influence the Horny Layer?

“…Downing et al [13] were able to show that SLS can be incorporated up to a concentration of 18% in liposomes whose lipid composition corresponds to a large extent to that of the lipids of the stratum corneum. The liposomes with incorporated SLS proved to be far more permeable to glucose than liposomes of the same type without SLS.…”

Confocal Raman Microspectroscopy for Evaluating the Stratum Corneum Removal by 3 Standard Methods

“…This method was discussed in the 60s by Kligman et al [32] . The method is well established and used for various purposes [33][34][35] and to quantify active amounts in percutaneous penetration studies [36,37] .…”