In this research, we developed a simple and reproducible electrochemical biosensor based on a gold electrode (GE) to detect DNA. Self-assembled monolayers (SAMs) of thiolated single-stranded DNA (SH-ssDNA), or BRCA1 5382 insC mutation detection (ssDNA), were immobilized on the electrode for a specific time. The immobilization of the probe and its hybridization with the target DNA were optimized using different experimental conditions. The modified electrode was characterized by electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV) and differential pulse voltammetry (DPV). It was observed that EIS approach had better analytical performance as compared with DPV. The linear range of the biosensor was estimated by EIS and found to be 1.0 x 10(-19)-1.0 x 10(-7) M with a detection limit of 4.6 x 10(-20) M. These results demonstrate that the new biosensor can be used to diagnose breast cancer. The biosensor showed excellent selectivity for discriminating complementary sequences from the noncomplementary sequence, so it can be used to detect breast cancer. Measurements of complementary DNA strains in the genome samples were done by EIS with satisfactory results. (C) 2015 Elsevier B.V. All rights reserved.