Triplex DNA logic gate based upon switching on/off their structure by Ag+/cysteine†
Abstract
The formation of intramolecular triplex DNA can be regulated by Ag+ and Cys (cysteine), which switch off/on the fluorescence of the oligonucleotides, 5′-TAMRA-TTC TCT TCC TCT TCC TTC TGA CGA CAG TTG ACT CTT CCT TCT CCT TCT CTT-BHQ-2-3′ (Oligo 1) and 3′-GAA GGA AGA GGA AGA GAA-5′ (Oligo 2). Based on this principle, sensors for Ag+ and Cys are developed. The sensor for Ag+ has a linear range of 2.5 nM–40 nM and a detection limit of 1.8 nM, whereas the sensor for Cys has a linear range of 10.0 nM–120.0 nM and a detection limit of 8.2 nM. Furthermore, the fluorescence is reversible with the alternate addition of Ag+ and Cys. We constructed a DNA logic gate using Ag+ and Cys as the input, and the fluorescence intensity as the output. The DNA logic gate is simple; moreover, it has a fast response and good reversibility.