A Biomimetic Multi-Stimuli-Response Ionic Gate Using a Hydroxypyrene Derivation-Functionalized Asymmetric Single Nanochannel

摘要

Biological nanochannels which can open and close in response to ambient stimuli play key roles in performing proper cellular and biological processes. In some cases, some of these nanochannels are responsive to not only one but a legion of chemical and physical stimuli. The channelrhodopsin-2 (ChR2), which can be found both in oocytes of xenopus laevis and mammalian cells, is a directly light/pH-switched ionic gate. This gate opens rapidly after absorption of a photon to generate a large permeability for monovalent and divalent cations, while closing ChR2 can be achieved by intracellular H~+. This expression of ChR2 may be used as a powerful tool to increase cytoplasmic cations concentration or to depolarize the cell membrane, simply by illumination and pH. The efficiency of regulating the ion transportation through biological membranes using pH or light as an environmental trigger has been a source of inspiration for chemists to mimic such processes using solid-state nanochannels. For example, a number of authors have demonstrated pH-gated ionic transport nanodevices by modifying pH-sen-sitive molecules such as polymer bruches and C4-DNA into a synthetic nanochannel, while others have presented light-gated nanochannels by grafting light-driven molecules, such as azobenzene and spiropyran. However, to build a light, pH, and light-and-pH cooperative nanofluidic system simultaneously with only one exoticism, precisely as nature does in ChR2, is a non-trivial task.