Electrochemical preparation of junction between a molecule and solid surface through a metal coordinative peptidic tag.

Molecular immobilization is a way of making a set molecules function as an interface. In order to fabricate a molecular interface, it is necessary to preserve the physical/chemical structure of the molecular layer. Almost all immobilization methods are based on chemical cross-linking reactions that lack orientation and reflect the original structure of the molecules. In order to fabricate a molecular interface which can be used in practical applications, we developed a novel method of molecular immobilization through electrochemical reactions. Our method is based on about the discovery of a novel interfacial phenomenon, i.e., that the coordinate metal ion in the peptidic ligand can be reduced and deposited on an electrode while preserving the bond between the metal and the ligand. The metal ion coordinative peptide tag (designed to contain less than 6 amino acids) can be deployed to objective molecule (e.g., proteins, peptides) in advance, either genetically or chemically. In the present electrochemical immobilization process, the coordinated Cu(2+) ion is reduced (deposited) on an electrode surface electrochemically, and the deposited metal remains bounded to the objective molecule-tagged peptidic ligand on a solid (electrode) surface. Using the EC tag tagged molecules, electrochemical molecular immobilization was performed, and an investigation of the surface properties was undertaken through both chemical quantifications and X-ray photoelectron spectroscopy (XPS). The complex formation between the ECtag tagged molecule and the metal ion was also investigated by photospectromitric analysis. All results suggest that ECtag tagged molecular immobilization is an interfacial phenomenon inducing neutral metal complex formation.