Ion-Selective Electrodes Based on Hydrophilic Ionophore-Modified Nanopores.

We report the synthesis and analytical application of the first Cu2+ -selective synthetic ion channel based on peptide-modified gold nanopores. A Cu2+ -binding peptide motif (Gly-Gly-His) along with two additional functional thiol derivatives inferring cation-permselectivity and hydrophobicity was self-assembled on the surface of gold nanoporous membranes comprising of about 5 nm diameter pores. These membranes were used to construct ion-selective electrodes (ISEs) with extraordinary Cu2+ selectivities, approaching six orders of magnitude over certain ions. Since all constituents are immobilized to a supporting nanoporous membrane, their leaching, that is a ubiquitous problem of conventional ionophore-based ISEs was effectively suppressed.