G-Quadruplexes Light up Localized DNA Circuits

DNA circuits tethered to nanoplatforms can perform cascade reactions for signal amplification. One DNA single strand activates a strand-displacement cascade generating numerous outputs, and therefore amplifying the signal. These localized circuits present, however, an important limitation: the spontaneous activation of the cascade reaction. Current methods to stabilize these circuits employ combination of protective DNA strands, which need to be removed to activate the device. This protection–deprotection process generates an important amount of unwanted side reactions. This is indeed an important limitation for the large potential application of these amplification circuits. In the present work, G-quadruplex DNA structures were used to stabilize localized DNA circuits. This new protocol generates nanoplatforms that no longer requires protective–deprotective systems and is therefore completely neutral to the sample. In addition, cations such as Pb2+ or Ca2+ can be also employed to activate the device enlarging the potential applications from biosensors devices to metal detector sensors.