a) Drawing shows a biological asymmetric hourglass-shaped ion channel with symmetric pH-gating ionic transport property. b) Our bioinspired smart single asymmetric hourglass nanochannel illustrates symmetric pH responsive ionic transport property after asymmetric functionalization of the large base side of the channel. c) Schematic representation of the cross section of the asymmetric hourglass PET nanochannel asymmetrically modified with PAA.

Synthetic stimuli-gated nanodevices displaying intelligent ion transport properties similar to those observed in biological ion channels have attracted increasing interests for their wide potential applications in biosensors, nanofluidics, and energy conversions. Here, bioinspired asymmetric shaped nanodevices are reported that can exhibit symmetric and linear pH-gating ion transport features based on polyelectrolyte-asymmetric-functionalized asymmetric hourglass-shaped nanochannels. The pH-responsive polymer brushes grafted on the inner channel surface are acted as a gate that open and close in response to external pH changing to linearly and symmetrically regulate transmembrane ionic currents of the channel. A complete experimental characterization of the pH-dependent ion transport behaviors of the nanodevice and a comprehensive discussion of the experimental results in terms of theoretical simulation are also presented. Both experimental and theoretical data shown in this work demonstrate the feasibility of using the asymmetric chemical modification method to achieve symmetric pH gating behaviors inside the asymmetric nanochannels, and lay the foundation to build diverse stimuli-gated artificial asymmetric shaped ion channels with symmetric gating ion transport features.

Advanced Functional Materials, 2015