"Electrochemical investigations of biological processes have provided a wealth of information on the structure-function relationship of redox enzymes, while the underlying technology has formed the basis for biosensors such as the extremely successful glucose biosensor. However, many of today’s applications do not impose molecular control on the electrode-protein interaction, which limits their full potential in biosensing, biological photo harvesting, biofuel cells and energy storage. While electrochemistry of globular redox-enzymes is limited by poor control of the surface-protein interface, the absence of control with membrane proteins has made it impossible to study them electrochemically. This in spite of the huge importance of membrane enzymes for biosensing and energy generation.To solve these problems, I have combined the state-of-the-art in surface physics, colloid and organic chemistry, membrane biology and electrochemistry to develop membrane-modified electrodes with full control of protein-electrode interactions. In this ERC Starting Grant proposal I aim to consolidate this research by applying this methodology to hydrogenases and light-harvesting reaction centres, both of which have promising applications in biofuel cells. Second, I will show how the combination of our membrane-modified electrodes with fluorescence spectroscopy provides an exciting application in single enzyme research, a challenge that has been met for only a handful of membrane proteins. Single-enzyme kinetics of a proton-pumping haem-copper oxidase will provide new insights into the molecular mechanism of proton-pumping. My long term vision of this work is to create electrodes that communicate with living cells, which will allow us to study bioenergetics in living cells and pave the way to harness bioenergy in biofuel cell applications. In this proposal I describe a first start in this ambitious vision by connecting my electrodes to living bacteria via their cytoplasmic membrane."