Surface potential generation by helical peptide monolayers and multilayers on gold surface

Self-assembled monolayers (SAMs) and multilayers of helical peptides were prepared and the surface potentials of the peptide layers were measured to evaluate the contribution of the dipole moment of helical peptides to the surface potential. hll the peptides have 2-aminoisobutyric acid (Aib), and adopt helical conformation in the peptide layers. The peptides were immobilized on gold surface by Au+-S- bond or hydrogen bonds to take a vertical orientation to the surface. When the helical peptides were connected to gold surface through the N terminal, the surface potentials were negative. On the other hand, the helical peptide layers exhibited positive surface potentials, when the peptides were connected through the C terminal. These results indicate that the dipole moment of helical peptide is the major factor for generation of the surface potential. The generation of surface potential by the helical peptides was also discussed in terms of a theoretical point of view.