Engineering ATP activated reversible nanochannel for gating of ion transport

Adenosine triphosphate (ATP) is an important purine molecule. It widely exists in cells and is closely related to a variety of significant physiological and pathological processes, such as energy metabolism, respiratory regulation, inflammation, and so forth. In vivo, ATP not only provides energy for organisms at the molecular level but also activates intracellular ion channels and regulates signaling pathways. Therefore, it is of great significance to construct ATP-responsive nanochannels for understanding complex biological processes. In this work, we designed and fabricated multi-amino conjugated rhodamine B (NH2-RhB) functionalized artificial nanochannels, which exhibited high performance for ATP response with current and fluorescence dual signals. Significantly, owing to the non-covalent bonding of NH2-RhB and ATP, the system performed reversible properties for regulating ion transport and behaved as an ionic gate that can flexibly switch between the "on" and "off" state under the condition of ATP and pH. The platform showed high selectivity for ATP and the detection limit can be as low as 48.2 fM. Moreover, finite-element theoretical simulation was employed to reveal the mechanism of ATP-activated nanochannel regulating ion flux. It proved that the surface charge density of the NH2-RhB functionalized nanochannels can be regulated by dealing with ATP and pH. This work shows promising applications of biomimetic nanochannel with gating properties and offers prospects for the development of biosensing, nano-device, and nanofluidic logic gates.