Permeability of Silicone-Water Interfaces in Water-in-Oil Emulsions

Water-in-silicone oil emulsions, stabilized by silicone-polyether surfactants, are marginally permeable to polar, but uncharged, molecules such as phenolphthalein and crystal violet. However, charged compounds, including these compounds in basic and acidic pH regimes respectively, and proteins transfer much less readily from the internal water phase to external bulk water. Transfer experiments were followed colorimetrically. These experiments shed light on the possible mechanisms by which proteins may be released from these emulsions in bioactive form: simple breaking of the emulsion does not appear to be the mechanism of action.