Electrochemical DNA biosensors offer simple and rapid tools for detection of DNA sequences or damaged genes associated with human disease. The performance of electrochemical DNA sensors is critically dependent on the quality of the DNA immobilisation. Many DNA biosensors have been focused on studying DNA hybridisation preformed under relatively mild assay conditions, while the development of stable DNA biosensors to study DNA damage under a much harsher condition typically in the presence of reactive oxygen species is more challenging. In this article, we developed an electrochemical DNA biosensor based on a stable diazonium-modified screen-printed carbon electrode (SPCE) for the detection of damage in DNA sequences related to the BRCA1 gene by using electrochemical impedance spectroscopy (EIS). The successful preparation of the DNA sensor was confirmed by FTIR-ATR, contact angle and electrochemical measurements. The DNA sensor exhibited good reproducibility and high stability and could also have potential for investigation of the glutathione antioxidant effect. (C) 2018 Elsevier B.V. All rights reserved.