Biological macromolecules have evolved over many millions of years into structures primed, in some cases, for both specific surface recognition and facile, directional electron tunnelling. The redox-active centres of metalloproteins play a central role in photosynthesis and respiration. The processes by which constructive man-made interfaces to these moieties can be generated have advanced greatly during the past two decades or so. Together with recent advances in molecular manipulation, analyses and lithographic fabrication, this knowledge has led to us to the point where bioelectronic devices can be designed and interrogated with good levels of reproducibility.