Figure 2.

(Left) Cyclic voltammetry (ν = 100 mV/s) of 4 μM MB/300 μM [K]₃[Fe(CN)₆] in Tris buffer, using the two-electrode multiplexed platform with a 127-μm spacer separating the primary- and secondary-electrode arrays. Data were recorded at four separate primary electrodes featuring an underlying 50/50 azide/phosphate monolayer, covalently modified with either well-matched (blue) or mismatched (red) alkyne-labeled DNA duplexes (18-mers). The solid traces were obtained at electrodes prepared by Cu(phendione)₂²⁺ activation at the corresponding secondary electrodes, while the dashed traces were obtained by activating Cu(phendione)₂²⁺ directly at the primary electrodes. (Right) Charges obtained by integrating the cyclic voltammograms. Electrodes prepared by catalyst activation at the secondary electrode display modest, though significantly better mismatch discrimination.