Ion‐Selective Electrodes Based on Hydrophilic Ionophore‐Modified Nanopores

We report the synthesis and analytical application of the first Cu(2+)‐selective synthetic ion channel based on peptide‐modified gold nanopores. A Cu(2+)‐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 Cu(2+) 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.