Flexible Single-Chain-Heteropolymer-Derived Transmembrane Ion Channels with High K⁺ Selectivity and Tunable pH-Gated Characteristics.

A series of single-chain random heteropolymer (RHP)-derived artificial ion channels with both high K⁺ selectivity and controllable pH-gated behaviors were fabricated by a facile "one-pot" polymerization method. The benzo-18-crown-6 moieties appended on lateral chains of RHPs can form ion-permeable nanopores and transport K⁺ over Na⁺ through the lipid bilayers. The ion permeation selectivity was significantly enhanced by incorporating a cholesterol group to serve as a membrane anchor. Interestingly, similar to natural gated protein channels, on-off switchable characteristics were also realized by integrating an additional acid-sensitive alkylamine group into the RHP-derived channel. The unique design strategies have endowed the RHP-derived ion channels with facile synthetic procedures, desirable membrane compatibility, high K⁺ selectivity, and tunable pH-gated properties. This work provides an entry point for future design of novel functional nanochannels.