An SECM study on the influence of cationic, membrane-active peptides on a gold-supported self-assembled monolayer

• SECM study of electron transfer through a SAM on gold is investigated.
• Membrane active peptides such as Tat and melittin are incorporated in SAMs.
• The identity of the peptide and mediator determines the rate of electron transfer.
• Electrostatic interactions between the mediator and surface dominate electron transfer.

The influence of the membrane active peptides, Tat44–57 (activator in HIV-1) and melittin (active content of bee venom), on self-assembled monolayers of 6-mercaptohexanoic acid (MHA) on gold electrodes has been studied with scanning electrochemical microscopy (SECM). It was found that MHA, when deprotonated at physiological pH, significantly affected the relative rates of electron transfer between the [Fe(CN)6]4− solution based mediator and the underlying gold electrode, predominantly by the electrostatic interaction between the mediator and MHA. Upon the introduction of Tat44–57 or melittin to the electrolyte, the relative rate of electron transfer through the MHA layer could be increased or decreased depending on the mediator used. However, in all cases it was found that these peptides have the ability to be incorporated into synthetic SAMs, which has implications for future electrochemical studies carried out using cell mimicking membranes immobilised on such layers.

Figure optionsDownload as PowerPoint slide