Ion‐Selective Electrodes Based on Hydrophilic Ionophore‐Modified Nanopores

We report the synthesis and analytical application of the first Cu(II)-selective synthetic ion channel based on peptide-modified gold nanopores. A Cu(II) 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 ca. 5 nm diameter pores. These membranes were used to construct Cu(II) ion-selective electrodes (ISEs) with extraordinary Cu(II) selectivities, approaching 6 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.