Artificial ion channels are introduced into a photosystem II photoelectrical conversion system to mimic the photocurrent regulating of the natural PSII energy system on the thylakoid membrane. In the composite system, PSII complexes act as pumps to convert light into currents and artificial ion channels act as valves to regulate light-induced ionic currents.

A novel and simple design is introduced to construct bichannel nanofluid diodes by combining two poly(ethylene terephthalate) (PET) films with columnar nanochannel arrays varying in size or in surface charge. This type of bichannel device performs obvious ion current rectification, and the pH-dependent tunability and degree of rectification can be improved by histidine modification. The origin of the ion current rectification and its pH-dependent tunability are attributed to the cooperative effect of the two columnar half-channels and the applied bias on the mobile ions. As a result of surface groups on the bichannel being charged with different polarities or degrees at different pH values, the function of the bichannel device can be converted from a nanofluid diode to a normal nanochannel or to a reverse diode.

Calcein-modified multiporous films with conical channels are introduced in a nanofluid device to enhance the calcium-responsive intensity and stability of ionic currents. Calcein with more carboxyls enhances the response of channels to calcium ions, and the capability of immobilized calcein for Ca(2+)-binding could be regulated by the deprotonation of these carboxyls.

One of the key processes of photosynthesis is to control the influx of atmospheric carbon dioxide (CO 2 ). Ion channels fulfill this process by regulating the opening and closing of stomatal pores in plants' leaves. Inspired by this natural process, we have developed an amidine-modified gas-responsive system that closely mimics stomatal pores: CO 2 rather than the variation in the pH value directly modulates the conductance state of the channel. The CO 2 -activated chemical reaction of amidine groups is reversible and produces an excess surface charge on the pore walls of asymmetric nanochannels, which makes the ions pass preferentially through the nanochannels in one direction relative to the conductance in the other direction, resulting in a significant ion current rectification. Furthermore, the influence of the different molecular conformation of the amidine-containing molecules on the current is investigated and discussed. The conclusive simulation of our system based on the Poisson and Nernst-Planck (PNP) model is also in good agreement with the experimental results. Accordingly, we have successfully mimicked the mechanism of stomatal closure in plants with our gas-activated nanosystem.

We developed an ion-gating nanochannel composite system by immobilizing a Cu(2+)-responsive self-cleaving DNAzyme into PET conical multinanochannels, which could control the ion transport by regulating the surface charge density of the channels.