Electrochemical biosensor based on modified reduced graphene oxide with silver nanoparticles for detection of methylated DNA

DNA methylation is one of the most studied and basic epigenetic process related to several diseases such as diabetes, neurodegenerative or cardiovascular diseases and even cancer. Methylated DNA presents a new generation of biomarkers which can be used for point-of-care detection. Electrochemical biosensors provide simple, fast, cost-effective, easy-to-use, reliable and efficient detection in contrast with conventional diagnostic methods. These biosensors can be used for early diagnosis of mentioned diseases and increase patient recovery by early clinical interventions. In this study, methylated DNA was detected electrochemically by the developed biosensor. The bare gold electrode was modified by drop-casting reduced graphene oxide with silver nanoparticles which enhance electrochemical signal due to their strong affinity to thiol modified DNA probe via a disulfide bridge. Afterwards, the sensitivity and selectivity of the nanocomposite were examined. The faradic electrochemical impedance spectroscopy was used for determination of the hybridization of the DNA probe with a methylated DNA sequence. The fabricated biosensor shows promising analytical features with a wide detection of the linear range.