Interfacial characteristics of the self-assembly system of poly- l-lysine 3-mercaptopropionic acid bgold electrode

Abstract

The interfacial characteristics of poly- l-lysine (PL) attached on self-assembled monolayers (SAMs) of 3-mercaptopropionic acid (MPA) were studied by an electrochemical method. The results indicated that PLMPA layer inhibited partly the diffusion process of redox species in solution, and the electrode surface behaved like a microelectrode array. Its permeation effect was also strongly affected by Mg 2+. The more Mg 2+ ions were added into the electrolyte solution, the greater the difficulty with which the electron transfer of potassium ferricyanide took place. The three different conformations of PL on the electrode surface had different influences on the electron transfer processes of ferricyanide. PL in random coil state hindered most strongly the electron transfer behavior of ferricyanide, while the α-helical PL had nearly no effect and the effect of the β-sheet state PL was intermediate of these.