Electrochemical sensor for guanine using a self-assembled monolayer of 1,8,15,22-tetraaminophthalocyanatonickel(II) on glassy carbon electrode

This article describes the selective determination of guanine (G) using the self-assembled monolayer (SAM) of 1,8,15,22-tetraaminophthalocyanatonickel(II) (4α-NiIITAPc) modified glassy carbon electrode (GCE) in 0.2 M acetate buffer solution (pH 4.0). The SAM of 4α-NiIITAPc was formed on GCE by spontaneous adsorption of 1 mM 4α-NiIITAPc in dimethylformamide (DMF). It shows two pairs of redox waves corresponding to NiIII/NiII and NiIIIPc-1/NiIIIPc−2 in 0.2 M acetate buffer solution. The SAM modified electrode exhibits excellent electrocatalytic activity toward the oxidation of G by enhancing its oxidation current with 150 mV less positive potential shift in contrast to bare GCE. Furthermore, the SAM modified electrode selectively determines G in the presence of high concentration of adenine (A). In differential pulse voltammetry measurements, the oxidation current response of G was increased linearly in the concentration range of 10 to 100 μM, and a detection limit was found to be 3 × 10−8 M (signal/noise = 3).