Droplet based measurement of specific capacitance and interfacial tensions

A method of determining the effect of a change in the chemical composition of an artificial cellular membrane, wherein the method comprises:

• (a) preparing an artificial cellular membrane at an interface between a first droplet and a second droplet of a first aqueous solution wherein the first aqueous solution comprises an amphiphilic molecule or mixture of amphiphilic molecules, and wherein the first droplet and the second droplet are each attached to separate electrodes and suspended in a hydrophobic liquid medium;
• (b) determining specific capacitance of the artificial cellular membrane, wherein the determining comprises determining a nominal capacitance and an artificial cellular membrane area at each of a plurality of artificial cellular membrane areas, wherein artificial cellular membrane area is varied by changing the position of the first or second droplet relative to the other of the first and second droplets, and optionally wherein the specific capacitance is calculated from the slope of a linear least squares regression of the nominal capacitance versus area data;
• (c) determining an artificial cellular membrane tension, wherein the determining comprises fixing the positions of the first and the second droplets relative to each other, measuring the contact angle of the droplets at a plurality of applied bias voltages, and calculating the monolayer and bilayer tension;
• (d) repeating steps (b)-(c) for an artificial membrane formed at the interface of a first and a second droplet of a second aqueous solution, wherein the second aqueous solution comprises an amphiphilic molecule or molecules, and wherein the chemical composition of the second aqueous solution differs from the chemical composition of first aqueous solution, and wherein the first and the second droplet of the second aqueous solution are each attached to separate electrodes and suspended in a hydrophobic liquid medium;
• and
• (e) comparing the data obtained in for the artificial cellular membrane formed with droplets of the first aqueous solution to that obtained for the artificial membrane formed with droplets of the second aqueous solution, thereby determining the effect of a change in chemical composition of the artificial cellular membrane.