Ion channels are membrane proteins of interest to medical research, drug discovery, and biosensing applications. Expressing ion channels and inserting them into lipid bilayers for characterisation using electrophysiology is conventionally a multi-step process involving the growth and transformation of cell lines followed by cell lysis, protein purification and reconstitution. This is a labour intensive, time consuming and cumbersome process that is often limited by low yields. In vitro transcription/translation is a fast, cell-free and commercially available approach to expressing proteins. A cell-free expression mixture contains all the necessary components for expressing proteins from a supplied DNA template. One drawback of this approach is that commercial cell-free systems are expensive, which has restricted their use to a small number of specific applications. However this is not an issue for lab-on-chip technology, where sample volumes are reduced to the microliter scale.
The aim of this project is to simultaneously express and characterise ion channels on-chip inside microdroplets using in vitro transcription/translation and electrophysiology. This is achieved using a droplet dielectrophoresis device capable of forming lipid bilayers by manipulating two microdroplets into contact inside a well that contains a lipid-oil solution. This transforms the conventional multi-day, multi-step single ion-channel electrophysiology method into a quick and economical process.