Continuously Tunable Ion Rectification and Conductance in Submicrochannels Stemming from Thermoresponsive Polymer Self-Assembly.

A biomimetic conical submicrochannel (tip side ca. 400 nm) with functions of continuously tunable ion rectification and conductance based on thermoresponsive polymer layer-by-layer (LbL) self-assembly is presented. These self-assembled polymers with different layers exhibited a capability to regulate the effective channel diameter, and different ion rectifications/conductance were achieved. By controlling temperature, the conformation and wettability of the assembled polymers were reversibly transformed, thus the ion rectification/conductance could be further adjusted subtly. Owing to the synergistic effect, the ion conductance could be tuned over a wide range spanning three orders of magnitude. Moreover, the proposed system can be applied for on-demand on-off molecule delivery, which was important for disease therapy. This study opens a new door for regulating channel size according to actual demand and sensing big targets with different size with one channel.