A sensitive, fast and inexpensive method for direct electrochemical detection of target DNA sequences in non-amplified genomic DNA samples is described. Hybridization detection relies on the alteration in guanine oxidation signal following hybridization of the probe with complementary genomic DNA. Initially, the method was tested to detect target DNA on low cycle number PCR amplicons. Having obtained promising detection results from only 5 cycles product, the feasibility of target sequence detection in extracted genomic DNA without PCR amplification, but with the vortex mediated fragmentation of the large genomic DNA into small pieces was examined. Experimental variables affecting the efficiency of sensor were investigated. Detection experiments with various non-complementary genomic DNAs as well as a proper probe, non-specific with respect to all genomic samples confirmed the excellent selectivity of the approach. The sensitivity of the method for analyzing the vortex mediated fragmentized genomic DNA samples is estimated to be approximately of 0.58 ng/mu l. (C) 2010 Elsevier Ltd. All rights reserved.