Reactive derivatives of gramicidin enable light- and ion-modulated ion channels

Abstract

Detection of chemical processes on a single molecule scale is the ultimate goal of sensitive analytical assays. We have explored methods to detect chemical analytes in solution using synthetic derivatives of gramicidin A (gA). We exploited the functional properties of an ion channel-forming peptideg—gA—to report changes in the local environment near the opening of these semi-synthetic nanopores upon exposure to specific external stimuli. These peptide-based nanosensors detect reaction-induced changes in the chemical or physical properties of functional groups presented at the opening of the pore. This paper discusses the development of gA-based sensors for detecting external factors such as metal ions in solution or for detecting specific wavelengths of light. We propose that gA-based ion channel sensors offer tremendous potential for ultra sensitive functional detection since a single chemical modification of each individual sensing element can lead to readily detectable changes in channel conductance.