Biological membranes are at once barriers and interfaces. They separate spaces and at the same time allow controlled transport and communication between them, the former being largely a function of the membrane lipids while the latter is the job of the membrane proteins.
Fig. 1: My first electrophysiological recording (Munich ca. 1982). Electrooculogram from a fellow medical student. She was reading “A la recherche du temps perdu”.
Fig. 2: My first action potential (Munich 1985). Intracellular recording from a rat sympathetic ganglion cell with a sharp electrode (a.k.a “glass nanopore”), filled with 3M KCl. Resistance approx. 50 MOhms.
Moreover, membranes generate all bioelectric signals and serve as the medium for cellular electrical signaling from graded, local potential changes to propagated action potentials by regulated flux of charged particles (ions). Finally, fusion and fission of membranes underlie transport of matter between cellular organelles and between them and the extracellular space (exo- and endocytosis) and a combination of exocytosis with regulated ion flux underlies synaptic communication between cells.
Electrophysiology is arguably still the most powerful, versatile, and quantitative method to study membrane function. It covers the entire spectrum from whole organismic systems (Fig. 1) to single cells (Fig. 2) and even single molecules (Fig. 3). As a real-time technique, electrophysiology lets you actually “feel the pulse” of single cells or even single molecules –a fascination that is sure to grip and never wanes.
At Behrendslab, electrophysiology is the basis of everything we do. Together with partners in microelectronics, microsystems technology and engineering, including companies spun out from the lab, we innovate to push it to new limits of resolution and throughput and combine it with other high resolution measurement techniques, such as optical recording, to enhance information content.
A current focus is the use of biological nanopores as sensors for single molecules in the context of future medical diagnostics. We play a central role in the Cluster4Future nanodiagBW, a large consortium of basic and applied research institutions and companies focusing on nanopore technology in the southwest of Germany.
Fig. 3: Single molecule detection (above) at high-resolution (110 kHz bandwidth) using an integrated nanopore-CMOS-amplifier device (below) developed in collaboration with the Hahn-Schickard Institute and Ionera GmbH. Freiburg 2022.
