Energy of Liposome Patch Adhesion to the Pipet Glass Determined by Confocal Fluorescence Microscopy

Abstract

The formation of the gigaseal in the patch clamp technique is dependent on the adhesion between the cell or liposome membrane and the glass pipet. The adhesion results in a capillary force causing creep of the patch membrane up the pipet. The membrane can be immobilized by counteracting the capillary force by positive pressure applied to the patch pipet. We use this phenomenon to develop a method for static measurement of the adhesion free energy of the lipid bilayer to the glass. Confocal fluorescent microscopy is used to track the bilayer creep inside the pipet and measure the immobilization pressure at various salt concentrations and pH. The adhesion energy is simply related to this pressure. For the studied phospholipid bilayers, its values were in the 0.3–0.7 mJ/m2 range, increased with salt concentration, and had a maximum as a function of pH. This method offers a way to measure bilayer–glass adhesion energy in patch clamp experiments that is more precise than dynamic methods.