A simple electrochemical biosensor for the detection of methylated DNA and for methyltransferase activity monitoring

DNA methylation is one of the well-known epigenetic mechanism which plays a crucial role in the development of various diseases, such as cancer, cardiovascular diseases or diabetes. Electrochemical biosensors promise excellent results for clinical diagnostics, especially in term of their sensitivity, stability, selectivity, portability, they are cost-effective, easy-to-use and provides a fast response. In this study, simply, reliably and selective DNA based electrochemical biosensor for detection of methylated DNA was fabricated. The proposed biosensor was modified with the synthesised reduced graphene oxide combined with gold nanoparticles (rGO-AuNPs). This nanocomposite has shown a strong affinity to the DNA probe and demonstrated promising analytical characteristics. The electrochemical impedance spectroscopy (EIS) was used for the characterization of interface properties of the gold electrode (GE). Additionally, the sensitivity of the developed biosensor was performed by differential pulse voltammetry (DPV) to investigate the activity of enzyme methyltransferase M.SssI (MTase). Fabricated biosensor offers quite a low detection limit (LOD), which was 3.2 U/ml and limit of quantification (LOQ) was 3.3 U/ml.