Divergent Pair of Ultrasensitive Mechanoelectronic Nanoswitches Made out of DNA.

Mechanoelectronic DNA nanoswitches refer to designed oligonucleotide constructs that are composed of conduction-interrupted duplex stems functionally coupled to ligand recognition motifs; they have been shown to undergo remarkable conduction switching upon binding molecular ligands/analytes. Herein we report a divergent pair of such mechanoelectronic DNA switches, the "signal-on" 3'AA-1 switch and the "signal-off" NB-1 switch, both activated by and responded to mercury ions (Hg) at nM levels. We first investigated their charge transport efficiency at a biochemical level, by studying how distinct base sequence at the switches' central three-way junction and at the recognition motif (capable of forming T-Hg-T metallo-base pairs) influences their overall conductivity.

Self-biotinylation of DNA G-quadruplexes via intrinsic peroxidase activity.

The striking and ubiquitous in vitro affinity between hemin and DNA/RNA G-quadruplexes raises the intriguing possibility of its relevance to biology. To date, no satisfactory experimental framework has been reported for investigating such a possibility. Complexation by G-quadruplexes leads to activation of the bound hemin toward catalysis of 1- and 2-electron oxidative reactions, with phenolic compounds being particularly outstanding substrates.