Elucidating the structure of DNA linkers tethered to electrode surfaces

In surface-grown biofilms, bacteria are surrounded by an extracellular matrix (ECM) comprising sugars, proteins and DNA. The mechanisms of extracellular electron transport through the ECM remain largely unknown, but it has recently been suggested that DNA may play a key role. However, the conductivity of DNA is thought to depend strongly on its structure. In the ECM, DNA mostly exists as bundles of folded DNA called G-quadruplexes (‘GQ-DNA’). We recently completed a neutron reflectometry experiment at ISIS where we were able to monitor the structure of tethered DNA fragments on a gold electrode surface in situ as the potential was varied. Here, we wish to extend this method to these highly relevant GQ-DNA systems, to understand how structural changes relate to their electron-transport abilities, and to characterise formation of multilayered networks at the electrode surface.