Résumé
Aquaporins (AQPs) are biological water channels known for fast water transport (~108-109 molecules/s/channel) with ion exclusion. Few synthetic channels have been designed to mimic this high water permeability, and none reject ions at a significant level. Here, we report artificial imidazole-quartet water channels with 2.6-Å pores, similar to AQP channels, that encapsulate oriented dipolar water-wires in a confined chiral conduit. These channels are able to transport ~106 water molecules per second, which is within two orders of magnitude of AQPs’ rates, and reject all ions except protons. The proton conductance is high (~5 H+/s/channel) and approximately half that of the M2 proton channel at neutral pH. Chirality is a key feature influencing efficiency. Natural KcsA channel conduct K+ cations at high rates excluding Na+ cations. Biomimetic artificial channels have been designed in order to mimick the ionic activity of KcSA channels, but simple artificial systems presenting high K+/Na+ selectivity are rare. Here we report an artificial ion-channel of H-bonded hexyl-benzoureido-15-crown-5-ether, where K+ cations are highly preferred to Na+ cations. The K+-channel conductance are interpreted as arising in the formation of oligomeric highly cooperative channels, resulting in the cation-induced membrane polarization and enhanced transport rates without or under pH-active gradient. These channels are selectively responsive to the presence of K+ cations, even in the presence of a large excess of Na+. From the conceptual point of view these channels express a synergistic adaptive behaviour: the addition of the K+ cation drives the selection and the construction of constitutional polarized ion-channels toward the selective conduction of the K+ cation that promoted their generation in the first place.