Ionophoric properties of polysorbate 80.

Polysorbate 80, a surfactant often assumed to be inert, was found to bind a number of biochemically important ions (K+, Na+, NH4+, Ca2+) and transport them through a model membrane (CH2Cl2). The rates and fluxes of potassium ions were found to depend on the initial concentration of potassium ion, the polysorbate 80 concentration, the temperature, and the stirring rate. The thermodynamic constants for the process were determined and its mechanism is discussed.