Methylene blue as an electrochemical discriminator of single- and double-stranded oligonucleotides immobilised on gold substrates.
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.
Tani
A
A
School of Chemical Sciences, University of East Anglia, Norwich, UK.
Thomson
A J
AJ
Butt
J N
JN
D000818:Animals; D002417:Cattle; D004563:Electrochemistry / Q000379:methods; D004791:Enzyme Inhibitors; D006046:Gold; D008751:Methylene Blue; D009841:Oligonucleotides / Q000032:analysis*
D004791:Enzyme Inhibitors; D009841:Oligonucleotides; D006046:Gold; D008751:Methylene Blue