Fig. 1.

E-DNA sensors and coadsorbates used: Here we have employed linear probe E-DNA sensors (top left) as a test bed with which to characterize the effects of surface chemistry on the properties of an electrochemical E-DNA sensor. Because hybridization reduces the rate with which the terminal redox tag collides with the electrode surface and transfers electrons the Faradaic current arising from such linear probes is significantly reduced in the presence of a complementary target sequence (top, right). It is thus likely that this suppression and the motion of the unbound and bound probe will be linked to the nature, steric hindrance and charge of the co-adsorbate used for sensor fabrication. We have tested the effects of a range of thiol co-adsorbates (bottom) differing in their length and/or terminal functional groups and chosen to cover a range of charges and sterics (bottom).