Template-free galvanic nanostructuring of gold electrodes for sensitive electrochemical biosensors

Gold nanostructuring of smooth gold disk-electrodes has been performed by electrodeposition. FE-SEM images indicate a strongly enlarged electrochemically active surface of the modified electrodes. This could be approved by the gold oxide reduction peak in cyclic voltammetry. The electrodes were also applied for sequence-specific DNA detection. For this, complementary single stranded capture probes were immobilized on the electrodes and consecutively hybridized with complementary and noncomplementary [OsO4(bipy)]-labeled DNA targets. We found that intermediate dehybridization steps did not decrease the sensitivity for the specific target. Moreover, the surface modification increased the voltammetric signal by an approx. factor of 9. Further, an enhanced linear calibration range was observed. The presented simple nanostructuring process holds great promise for many electrochemical sensor applications.