Methylene blue as an electrochemical discriminator of single- and double-stranded oligonucleotides immobilised on gold substrates

Akiko Tani, Andrew J. Thomson, Julea Butt

Research output: Contribution to journalArticlepeer-review

103 Citations (Scopus)


Self-assembly of thiol-terminated oligonucleotides on gold substrates provides a convenient and versatile route to DNA-functionalised surfaces. Here we show that the square-wave voltammetric peak position of methylene blue complexed to thiol-terminated single-stranded oligonucleotides immobilised on gold electrodes differs from that of methylene blue complexed to thiol-terminated double-stranded oligonucleotides immobilised on gold electrodes. The peak potential of methylene blue at the single-stranded oligonucleotide array was consistently found to occur at potentials ca. 10–15 mV more positive than that at double-stranded oligonucleotide arrays, the precise difference being dependent on the direction of the voltammetry. This voltammetric behaviour mirrors that found for methylene blue bound to freely diffusing single- and double-stranded calf thymus DNA and suggests that the immobilised oligonucleotides retain the methylene blue binding properties of their freely diffusing counterparts. Thus methylene blue provides a simple electrochemical indicator for the status of oligonucleotide-functionalised gold surfaces.
Original languageEnglish
Pages (from-to)1756-1759
Number of pages4
JournalThe Analyst
Issue number10
Publication statusPublished - 25 Sep 2001

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