Macromolecule transport in and effective pore size of ethanol pretreated human epidermal membrane

Abstract This study has examined the transport behavior of macromolecules of up to about 18 000 molecular weight (Mol. Wt) and the feasibility of using the theory of restricted diffusion of molecules through cylindrical pores to predict/characterize the pore sizes of synthetic membranes and ethanol pretreated human epidermal membrane (HEM). To minimize membrane and skin variabilities, experiments were conducted consecutively with each membrane using a two-chamber diffusion cell. Reference permeants or electrical resistance measurements were used to monitor possible membrane changes during a given set of runs. All HEM specimens exhibited the same pattern of significantly decreasing permeability with increasing polystyrene sulfonate (PSS) molecular weight. Previously obtained permeability data for ethanol pretreated HEM with polypeptides (leuprolide, CCK-8 and insulin) were found to be consistent with those for PSS; comparable permeability coefficients were observed for polypeptides and PSS's of comparable sizes. An analysis based on the theory of restricted diffusion for PSS transport across a synthetic Nuclepore® membrane yielded results consistent with the nomical pore size ( ∼ 75 A ) of this membrane. A similar analysis of the PSS data obtained with ethanol pretreated HEM yielded estimates of effective pore size for this membrane in the range, 22–54 A.