A regenerating self-assembled gold nanoparticle-containing electrochemical impedance sensor.

We report on the development of an electrochemical reductive desorption protocol for repeated regeneration of gold electrodes modified with multi-layers of self-assembled surfaces for use in electrochemical sensing. The gold electrodes were first modified with 1,6-hexanedithiol to which gold nanoparticles were attached in a subsequent modification step. Attachment of thiolated single-stranded nucleic acid oligomers to the gold nanoparticles completed the electrochemical sensor. The changes of electrode behavior after each assembly and desorption processes were investigated by cyclic voltammetry, electrochemical impedance spectroscopy and X-ray photoelectron spectroscopy techniques. The self-assembled sensor showed a wide dynamic range (0.1-100 nM), a low detection limit (20 pM) and high reproducibility (4.4% RSD) for complementary nucleic acid target molecules, along with reusability. On a single gold electrode, the complete sensor-target structure could be assembled and disassembled at least four times with 90% of its original signal intact.