A Temperature-, pH- and Voltage-Responsive Nanogate with a Remarkably High Factor of Change in Ion Currents due to ON/OFF Switching.

Abstract

In biological cells, nuclear pore complexes (NPCs) embedded in cell membranes are capable of controlling the flow of ions, for example, Na+ , K+ , and Ca2+ by responding to stimuli, for example, pH and voltage. Inspired by NPCs, researchers have been endeavoring to develop nanogates to achieve the control of ion transport, but the developed nanogates only have a low factor of change in ion currents due to ON/OFF switching. As such nanopores with high temperature and pH responsivities were developed in this work. According to the experimental results, at a voltage of 3 V, the change in ion currents due to pH change is up to a factor of 170, which is remarkably high compared to other nanogates reported. Quantum chemical (QC) calculation results show that a protonated cytosine molecule (C+ ) and an unprotonated cytosine molecule (C) form three pairs of hydrogen bonds and consequently a nucleobase pair, CC+ , leading to the binding of various strands, assembly of a strand net, and blockage of ion transport. The nanogate developed is capable of responding to temperature change. At a voltage of 3 V, the factor of change in ion currents in response to temperature variation is as high as 110. Further experiments were performed to investigate the influence of the NaCl concentrations and small opening diameters exerted on nanogate performance.