Imaging potassium-flux through individual electropores in droplet interface bilayers

•Optical imaging of potassium flux through individual electropores•Droplet interface bilayer imaging quantifies membrane permeabilization.•Kryptofix-222 improves resolution of APG-4 fluorescence response.

Using total internal reflection fluorescence microscopy of droplet interface bilayers containing the potassium-sensitive fluorophore APG-4, we imaged the ionic flux through individual electropores. We are able to monitor up to 30 individual pores in parallel and show voltage dependent responses in fluorescence that corresponds to the measured ionic current. These experiments help quantify the scope and current limitations of optical single channel recordings of potassium flux. This article is part of a Special Issue entitled: Pore-Forming Toxins edited by Mauro Dalla Serra and Franco Gambale.