Electrochemical detection of cytosine and 5-methylcytosine on Au(111) surfaces

• Adsorption–desorption of both molecules on Au is surface structure sensitive.
• On Au(111), a linear correlation between concentration and peak potential is observed.
• The presence of mC mainly determines the resulting electrochemical response.
• In mC-C mixtures, the presence of mC can be electrochemically determined.
• FTIRs studies do not provide clear evidences of the mC voltammetric selectivity.

In this communication we report a voltammetric study of the adsorption–desorption of cytosine (C) and methylcytosine (mC) on well-defined gold (Au) electrodes. The voltammetric measurements clearly indicate that these processes are extremely sensitive to the Au surface structure and in particular to the presence of (111) surface domains. Interestingly, on Au(111) surfaces, a linear correlation between the C and mC concentrations (logarithm scale) and the peak potential of the main voltammetric feature is found. In addition, in the simultaneous presence of both molecules, mC governs the electrochemical response, which has allowed its accurate quantification in C-mC mixtures. In situ FTIR spectroscopic measurements have been carried out to deepen on this mC electrochemical sensitivity. This research may contribute to the future development of an electrochemical sensor for the determination of the degree of methylation in DNA.

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