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) (4 alpha-N(II)TAPc) modified glassy carbon electrode (GCE) in 0.2 M acetate buffer solution (pH 4.0). The SAM of 4 alpha-Ni(II)TAPc was formed on GCE by spontaneous adsorption of 1 mM 4 alpha-Ni(II)TAPc in dimethylformamide (DMF). It shows two pairs of redox waves corresponding to Ni-III/Ni-II and (NiPc-1)-Pc-III/(NiPc-2)-Pc-III 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 mu M, and a detection limit was found to be 3 x 10(-8) M (signal/noise = 3). (c) 2012 Elsevier Inc. All rights reserved.