The differentiation of fully matched and unlabelled Influenza A (Inf A) or B (Inf B) target DNA obtained from polymerase chain reaction (PCR)-amplified real samples towards non-complementary sequences have been analyzed with an extremely simple electrochemical methodology by developed label-free electrochemical DNA biosensor without any surface modification. In the meanwhile, this is the first study that contains the solution of the guanine signal-based displaying problem of DNA hybridization which has been solved by designed biosensor. The monitoring of guanine oxidation signal affected by experimental conditions and the response showed significant differences depending on the nature and composition of DNA. In the presented work, the effect of differences in the number of inosine in probe DNA on hybridization imaging was also discussed. The electrochemical oxidation of guanine (approximately +1.00V) was measured at pencil graphite electrode (PGE) by using differential pulse voltammetry (DPV) technique and evaluated before and after hybridization between probe and target DNAs. Several hybridization solutions and rinsing protocols with different ionic strengths have been utilized to achieve optimum hybridization displaying response. The selectivity of developed genosensor was also tested at the same time with hybridization. The detection limits of sensors were calculated as 35 nM for Inf A and 21 nM for Inf B sequences. (C) 2018 Elsevier B.V. All rights reserved.