Label-free electrochemical analysis of purine nucleotides and nucleobases at disposable carbon electrodes in microliter volumes

Abstract

We analyzed purine nucleotides in oligodeoxynucleotides (ODN) and nucleobase residues acid-hydrolyzed ODN at nanomolar concentrations in few tens of microliters of solution at commercially available unmodified graphite pencil electrodes, screen printed graphite electrodes (SPGEs) and SPGEs modified by graphene, single- and multi-walled carbon nanotubes. Our results suggest that specific properties of different graphite-based electrodes have significant impact on ODN analysis. Nanostructure-modified electrodes produced higher signals due to purine nucleobase oxidation but also higher background currents. The unmodified disposable carbon electrodes allowed analysis of both free nucleobases and ODNs. Our results show that unmodified SPGEs represent a good compromise for signal/noise ratio. Electrooxidation of purines at these electrodes was only little affected by the presence of pyrimidines in contrast to the pencil graphite electrode.