Fig. 1. Comparison of MCH-modified, ssDNA-modified and Cas-treated electrodes (with 10 nM target gene) using (a) cyclic voltammetry (CV), (b) square wave voltammetry (SWV), (c) electrochemical impedance spectroscopy (EIS) and (d) controlled potential coulometry. For cyclic voltammograms and Nyquist plots, 10 mM [Fe(CN)6]^3−/4− in 0.1 M PBS was used as the working solution, and 0.1 M PBS was used as the background electrolyte. Square wave voltammograms of silver-metallized electrodes were carried out using a step potential of 0.01 V, an amplitude of 60 mV, and a frequency of 200 Hz. The reversible cyclic voltammograms were carried out using a scan rate of 100 mV s⁻¹, while Nyquist plots were obtained by applying a 5 mV sine wave potential within a frequency range of 10⁻² to 10⁵ Hz. For coulometry, silver was deposited using a similar protocol as SWV, then applying 0.5 V potential for 30 seconds to collect the silver metallization amount on the electrode.