BIOMIMETIC MACROMOLECULAR CHEMISTRY - DESIGN AND SYNTHESIS OF AN ARTIFICIAL ION CHANNEL BASED ON A POLYMER CONTAINING COFACIALLY STACKED CROWN-ETHER RINGS - INCORPORATION IN DIHEXADECYL PHOSPHATE VESICLES AND STUDY OF COBALT ION-TRANSPORT

We describe a synthetic model of a natural channel-forming ionophore. It is based on a polymer with a rigid backbone, viz. a polymer of an isocyanide, [R-N=C<]n. Each of the polymer side chains R contains a crown ether ring. Due to the rigid 4/1 helical structure of the polymer the crown ether rings are cofacially stacked and form four channels which run parallel to the polymer helix axis. The channels are better ion-complexing agents than low molecular weight crown ethers. Evidence is presented that the channel structures can be incorporated in the bilayers of dihexadecyl phosphate vesicles. Electron microscopic data, fluorescence experiments, as well as entrapment studies indicate that the vesicle bilayers are not disrupted by the channels. lon transport studies are presented which reveal that the channel structures enhance the permeability of the dihexadecyl phosphate membranes by forming transmembranous pores.