Spectroscopy and Electrochemistry of Peptide-Based Self-Assembled Monolayers

Mono and bi-component peptide-based self-assembled monolayers (SAMs) immobilized on a gold surface were studied by electrochemical and spectroscopic techniques. The peptides investigated were exclusively formed by Ca-tetrasubstituted amino acids. These residues, due to their peculiar conformational properties, constrain the peptide in a helical conformation, as confirmed by X-ray diffraction structure determinations, and Circular Dichroism and NMR experiments in solution. Both mono-and bi-component peptide SAMs were functionalized with electroactive, fluorescent chromophores strongly absorbing in the UV region. While electrochemical experiments indicated the formation of densely-packed films on the gold surface, fluorescence spectroscopy revealed the occurrence of aromatic-aromatic interactions between the pyrene units functionalizing the peptide chains, obtaining important information on the structural and dynamical properties of the peptide SAMs investigated.