Broadly Accessible Assays with Signal Amplification across Lipid Bilayers

Abstract

Over the past decade, droplet interface bilayers (DIBs) have emerged as a robust platform for performing studies across lipid membranes with the potential for high-throughput applications. Here we explore the potential of DIBs for detecting the presence of analytes in a heterogeneous sample without the need for an external power source. We discuss the formation of DIBs by a broadly accessible and straightforward pipetting step leading to stable DIBs between two aqueous reservoirs with a proton gradient across the bilayer interface. When a pore-forming peptide is present, the pH of the reservoirs change, which can be detected by the unaided eye based on the color change of a pH sensitive dye. This approach takes advantage of bio-inspired amplification in the sense that one ion channel, after analyte-triggered activation, facilitates the flux of thousands of ions across the DIB. We describe our attempts to impede H+/OH- flux using known pore blockers in order to detect alterations in the rate of color change in the presence of these molecules. We also discuss the possibility of using pore-forming peptides engineered to alter their function in the presence of a specific analyte in order to detect this analyte within a sample. Our ultimate goal is to develop an assay to screen samples of biofluids in a broadly-accessible and robust manner that can be adapted to various analytes and biomarkers.