Double Step Electrochemical Etching for Reuse of Gold Screen Printed Electrode

Gold (Au) is of considerable interest for electrochemically active surfaces because thiol-modified chemicals and biomolecules can be easily immobilized through a simple procedure. However, most Au surfaces are damaged after repetitive measurements, making them difficult to reuse. Here, we present a novel electrochemical (EC) etching method for Au surfaces that enables electrode reuse through a simple, nontoxic, and straightforward protocol. This process, referred to as double-step EC etching (DSEE), consists of two sequential steps: (i) a cyclic voltammetry (CV) sweep in a very low concentration of H₂SO₄, followed by (ii) a CV sweep in K₃Fe-(CN)₆. For comparison, alternative etching methods were also evaluated. After the assembly and subsequent desorption of cells and antigens, changes in the performance of the Au electrode as both an immunosensor and a cytosensor were examined using EC impedance spectroscopy and CV. Repetitive measurements were found to be feasible for up to five cycles while maintaining reproducibility. We believe that this Au electrode reuse method can be applied to long-term, cost-effective, and accurate monitoring of biological effects.