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© 1986 Society of Cosmetic Chemists
Journal of the Society of Cosmetic Chemists, Vol. 37, No. 3, 125-139

Surfactant structure effects on swelling of isolated human stratum corneum
L. D. Rhein , C. R. Robbins , K. Fernee , R. Cantore



Many surfactants in solution induce swelling of isolated human stratum corneum beyond that of water (1–3). The highest levels of swelling observed were for anionic surfactants, and very little swelling occurs with cationics and nonionics (3). Stratum corneum swelling is frequently accompanied by curling of the membrane edges (4). We have now extended these studies to examine effects of other surfactants on swelling of stratum corneum.

Swelling caused by surfactants increased with time, was concentration-dependent, was saturable with increasing concentration, and was reversible. Apparent saturation for sodium lauryl sulfate (SLS) occurs near the critical micelle concentration. The extent of swelling was reduced with increased ethoxylation of alkyl (C 12 –C 14 ) sulfate. When Mg 2+ or triethanolamine were the counter ions rather than Na + , swelling by lauryl sulfate was reduced. For homologous series of various anionic surfactants (alkyl benzene sulfonates, alpha olefin sulfonates, alkyl sulfates, and paraffin sulfonates), maximal swelling occurred at either C12 or C14 carbon atoms. For cationic surfactants, membrane shrinkage rather than swelling occurred at the longer incubation times. Surfactant interactions to reduce swelling were found, e.g. addition of alkyl ethoxy sulfates or amphoterics to SLS produced less swelling than the SLS alone. The results suggest mechanisms of action and a basis for in vivo irritancy of surfactants.

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© 1986 Society of Cosmetic Chemists
Journal of the Society of Cosmetic Chemists