Electronic properties for detection of DNA methylation

Detection of DNA methylation is of great significance for early diagnosis and precise treatments of related cancers. We calculated electronic properties of base pairs including cytosine (C), 5-methylcytosine (5mC), 5-hydroxymethylcytosine (5hmC), 5-formylcytosine (5fC) and 5-carboxylcytosine (5caC) with guanine (G). Calculation results show that modifications can regulate the energy gap of base pairs mainly by changing distributions of frontier orbitals and would not reduce the efficiency of charge transfer in DNA. 5fCG and 5caCG have better electrical transport properties due to the narrower gap and higher electron affinity compared with that of CG. Modified base pairs would remain stable when charge transport and not notably strengthen or weaken hydrogen bonding interactions of paired bases. Moreover, transverse electronic transport properties of benzamide with C and 5mC were studied by using the density functional theory (DFT) combined with the non-equilibrium green function (NEGF). The obtained current values of two systems have obvious difference under 0-0.2V biases, thus realizing the distinction of methylated cytosine. (paper)