INTERFACIAL CHARACTERISTICS OF THE SELF-ASSEMBLY SYSTEM OF POLY-L-LYSINE 3-MERCAPTOPROPIONIC ACID GOLD ELECTRODE

The interfacial characteristics of poly-L-lysine (PL) attached on self -assembled monolayers (SAMs) of 3-mercaptopropionic acid (MPA) were st udied by an electrochemical method. The results indicated that PL\MPA layer inhibited partly the diffusion process of redox species in solut ion, and the electrode surface behaved like a microelectrode array. It s permeation effect was also strongly affected by Mg2+. The more Mg2ions were added into the electrolyte solution, the greater the difficu lty with which the electron transfer of potassium ferricyanide took pl ace. The three different conformations of PL on the electrode surface had different influences on the electron transfer processes of ferricy anide. PL in random coil state hindered most strongly the electron tra nsfer behavior of ferricyanide,while the alpha-helical PL had nearly n o effect and the effect of the beta-sheet state PL was intermediate of these. (C) 1997 Elsevier Science S.A.