Abstract:
Biosensor read out signals can be enhanced by carefully designing the transducer surfaces to achieve an
optimal interaction between the recognition elements immobilised and the targeted analyte. This is particularly evident in the case of genosensors, where spacing and orientation of immobilised DNA capture
probes need to be controlled to maximise subsequent surface hybridisation with the target sequence
and achieve high binding signals. Addressing this goal, we present a novel approach based on the surface
nanostructuring of glassy carbon electrodes (GCEs) towards the development of highly sensitive electrochemical genosensors. Gold nanoparticles were sequentially electrochemically nucleated on glassy
carbon electrodes to form dense arrays of randomly distributed gold nanodomains. The number density of the electronucleated nanoparticles could be increased by repeatedly alternating between a short
electronucleation step and the subsequent insulation of the nucleated nanoparticles with thiolated DNA
probes. This approach allowed for the creation of highly structured surfaces whilst preventing aggregation of nanoparticles. The performances of planar gold electrodes and that of the nanopatterned surfaces
prepared following several rounds of deposition were compared for the amperometric detection of DNA.
Three rounds of deposition exhibited the highest sensitivity (44.89 nA × nM−1), with a dynamic detection
range spanning from 0.53 nM to 25 nM of the targeted sequence, i.e. one order of magnitude lower than
that obtained for the planar gold electrodes. The use of the nanostructured surface we report here may
find application not only in DNA biosensors but also for any sensing application requiring highly sensitive
measurements
