Comparison of the structural behaviour of two flavins at the electrode/electrolyte interface under applied potential.

This proposal concerns the structural behaviour of two flavins that act as mediators between electroactive biofilms and electrodes by transferring electrons from the bacterial cell membrane to the electrode surface. This is currently the rate-limiting step in bioelectrochemical devices that use these light-harvesting biofilms to generate electricity and the nature of the biofilm/electrode interaction remains poorly understood. Specifically, it has been proposed from previous electrochemical measurements that the two flavins (that differ only by one phosphate group) may form very different structures at the electrode surface and may behave differently when a potential is applied. However, structural analysis of these systems is lacking and so neutron reflectometry offers the perfect technique to verify or reassess these predictions in situ using a custom-made electrochemical cell.