Direct potential resolution and simultaneous detection of cytosine and 5-methylcytosine based on the construction of polypyrrole functionalized graphene nanowall interface

•An efficient electrochemical interface was constructed for the recognition of DNA methylation information.•The conductive graphene nanowall layer altered the mass transport regime of analytes.•The direct potential resolution between cytosine and 5-methylcytosine was 184 mV.•The present work realized the evaluation of DNA methylation level in CpG oligonucleotides.•This method exhibited advantages of rapidity, convenience, accuracy and universal analysis.

Herein, an efficient approach was developed for direct electroanalysis of DNA methylation based on the construction of polypyrrole functionalized graphene nanowall interface. Taking advantage of the physicochemical properties of graphene nanowall layer, the mass transport regime of analytes was changed from planar diffusion to thin layer diffusion. As a result, the oxidation signal of 5-methylcytosine (mC) was clearly distinguished from that of cytosine (C) with a direct potential resolution of 184 mV, which paved the way for simultaneous detection with high reliability. Moreover, the proposed method realized the evaluation of DNA methylation level in CpG oligonucleotides in a straightforward, rapid, convenient, label-free and hybridization-free way, suggesting that the system is promising for sensing applications.