Water-insoluble statistical copolymer was synthesized by copolymerization of methyl methacrylate (MMA) with 2-(dimethylamino)ethyl methacrylate (DMA) via group transfer polymerization (GTP). The DMA residues of the precursor P(MMA-co-DMA) statistical copolymer were then quaternized by reacting with methyl iodide under mild conditions to get well-defined P(MMA-co-QDMA) cationic copolymer. Then, P(MMA-co-QDMA) copolymer was successfully used for surface modification of pencil graphite electrode (PGE) to develop a disposable DNA sensor. This P(MMA-co-QDMA) copolymer modified electrode (q-PGE) was examined for electrochemical monitoring of DNA by using differential pulse voltammetry (DPV) in contrast to unmodified one. The effect of both DNA concentration and sonication time was also examined based on the response of q-PGE. The detection limit was calculated to be 8.06 mu g/mL at q-PGE. Electrochemical impedance spectroscopy (EIS) was used for the characterization of the surface modification of q-PGE and consequently, the results were found to be in good agreement with the voltammetric measurements. (C) 2012 Elsevier B.V. All rights reserved.