The very specific binding of the HgII ion unexpectedly and significantly stabilizes naturally occurring thymine-thymine base mispairing in DNA duplexes. Following this finding, we prepared DNA duplexes containing metal-mediated base pairs at the desired sites, as well as novel double helical architectures consisting only of thymine-HgII-thymine pairs.

Very specific binding of the Ag(i) ion unexpectedly stabilized DNA duplexes containing the naturally occurring cytosine-cytosine (C-C) mismatch-base pair; because the C-C pair selectively binds to the Ag(i) ion, we developed a DNA-based Ag(i) sensor that employed an oligodeoxyribonucleotide containing C-C pairs used for Ag(i) binding sites.

Mercury gauge: An oligodeoxyribonucleotide(ODN)‐based sensor, which carries energy‐donor and ‐acceptor moieties (fluorescein, F, and dabcyl, D, respectively), selectively detects HgII ions in aqueous solution. Upon binding HgII ions, the ODN takes on a hairpin structure (see picture); this results in a decrease in the fluorescence emission through enhanced FRET (fluorescence resonance energy transfer) from F to D.