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.