A Synthetic Phospholipid Derivative Mediates Ion Transport Across Lipid Bilayers

Inspired by the natural phospholipid structures for cell membrane, a synthetic phospholipid LC with an ion recognition group benzo-18-crown-6 (B18C6) moiety was prepared which has been demonstrated to be able to transport ions across the lipid bilayers. Fluorescent vesicle assay shows that LC has an excellent transport activity, and the EC₅₀ value for K⁺ is 11.2 μM. The voltage clamp measurement exhibits regular square-like current signals with considerably long opening times, which indicates that LC achieves efficient ion transport through a channel mechanism and its single channel conductivity is 17 pS. Both of the vesicle assay and patch clamp tests indicate that LC has selectivity for Rb⁺, whose ionic radius is larger than the cavity of crown ether. It suggests that the sandwich interaction may play a key role in the ion transport across lipid bilayers. All these results help us to speculate that LC transports ions via a channel mechanism with a tetrameric aggregate as the active structure. In addition, LC had obvious toxicity to HeLa cells, and the IC₅₀ was 100.0 μM after coculture for 36 h. We hope that this simple synthetic phospholipid will offer novel perspectives in the development of more efficient and selective ion transporters.