Patent ID: 8901042

Claim:
An assay for measuring the effect of a test substance on a lipid bilayer, comprising: providing vesicles composed of a lipid bilayer, a pair of an indicator and a monovalent cation, and gramicidin, wherein the vesicles encompass one member of the pair of the indicator and the monovalent cation, and comprise gramicidin in the lipid bilayer; wherein the lipid bilayer is formed using phospholipids selected from the group consisting of di-C 22:1 -, di-C 20:1 -, di-C 18:1 -, 1-C 16 -2-C 18:1 -acyl chains, and combinations thereof, in the absence or presence of cholesterol; and wherein molecules of gramicidin present in the lipid bilayer are in a monomer-dimer equilibrium in favor of monomer; treating at least a portion of the vesicles with said test substance; exposing the vesicles to a solution containing the other member of the pair of the indicator and the monovalent cation, wherein movement of said monovalent cation across the lipid bilayer through a conducting gramicidin channel causes the indicator to generate a detectable signal, wherein said detectable signal is indicative of the rate of monovalent cation movement across the lipid bilayer and is indicative of the density of conducting gramicidin channels in the lipid bilayer; comparing the detectable signal generated from the vesicles treated with the test substance with the detectable signal generated from the vesicles not treated with the test substance, wherein a difference in the detectable signals correlates with the effect of said test substance on said lipid bilayer; and determining the effect of said test substance on said lipid bilayer based on the comparison.