Electrochemical monitoring of surface confined interaction between 6-Thioguanine and DNA by using single-use graphite electrode

In the present work, the electrochemical detection of interaction between 6-TG and calf thymus double stranded DNA (dsDNA) was explored by using single-use pencil graphite electrode (PGE) in combination with differential pulse voltammetry (DPV) and electrochemical impedance spectroscopy (EIS) techniques. Firstly, the electrochemical behaviour of 6-TG was investigated voltammetrically by using PGE, and the two oxidation signals of 6-TG were measured at +0.25 V and +0.78 V. Experimental parameters, such as 6-TG concentration and interaction time were optimized based on the changes at the 6-TG signal observed at +0.25 V since the latter one overlapped with the oxidation signal of guanine measured at +0.95 V. The results based on the impedimetric analysis for interaction between 6-TG and dsDNA were consistent with the voltammetric results. The electrochemical monitoring of surface confined interaction between 6-TG and single stranded Oligo (A)(25), or double stranded Oligo (A)(25)-Oligo (T)(25) was explored based on the changes at the oxidation signals of 6-TG and adenine by using DPV. The single-use graphite sensor represented a sensitive, rapid and cost effective detection protocol for electrochemical monitoring of the interaction between 6-TG and DNA. (C) 2014 Elsevier B.V. All rights reserved.