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

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. (C) 2015 Elsevier B.V. All rights reserved.