An electrochemically actuated reversible DNA switch.

In this Letter, we have realized the electrical actuation of a DNA molecular device in a rapid and reliable manner with a microfabricated chip. The three-electrode chip containing Ir, IrO(2), and Ag electrodes deposited in designed shapes and positions on the SiO(2) surface was made by photolithography and magnetron reaction sputter deposition technology. In this design, the negative feedback property enabled the system to rapidly change and maintain the solution pH at arbitrary value by water electrolysis. As a proof-of-concept, we can drive a DNA switch based on the opening and close of an i-motif structure by switching the potential between the working and reference electrodes between -304 and -149 mV. We have demonstrated that DNA can be electrically switched within seconds, without obvious decay of the fluorescence amplitudes for at least 30 cycles, suggesting that this DNA switch is rapid in response and fairly robust. We have also demonstrated that this device could manipulate the DNA switch automatically by using chronoamperometry.