Chitosan-(CHIT) and ionic liquid- (1-butyl-3-methylimidazolium hexafluorophosphate (IL)) modified single-use graphite electrodes (PGEs) were developed for the first time in the present study for the enhanced monitoring of DNA, and also for sequence-selective DNA hybridization by measuring the guanine oxidation signal. The electrochemical behaviour of the CHIT-IL modified electrodes was first investigated (with unmodified electrodes as controls) using electrochemical impedance spectroscopy (EIS) and differential pulse voltammetry (DPV). Sequence-selective DNA hybridization related to Hepatitis B virus (HBV) was also evaluated in the case of hybridization between amino-linked HBV probe and its complementary (target), a noncomplementary (NC) sequence, single base mismatch (MM), and also in the medium of target/mismatch (MM) mixtures (1:1). CHIT-IL modified PGEs presented a very effective discrimination of DNA hybridization owing to their superior selectivity and sensitivity. (C) 2013 Elsevier B.V. All rights reserved.