Effects of Mg2+ on Supported Bilayer Lipid Membrane on a Glassy Carbon Electrode during Membrane Formation

The effects of Mg2+ on supported bilayer lipid membrane (s-BLM) during membrane formation were investigated by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). There was an increase of the peak-to-peak separation between the cathodic and anodic waves from CV, and an obvious decrease of charge transfer resistance from EIS for the membrane formed in 0.1M MgCl2 compared with that in 0.1M KCl. The higher ionic strength of MgCl2 led to more lipid molecules dropping from the surface of the electrode before they were ready to be in directional arrangement to form s-BLM, so the membrane was not so dense. When reducing the concentration of MgCl2 to 0.03M or 0.05M, the total resistance decreased during the scanning process, which suggested the structure of the lipid membrane changed. The interaction between Mg2+ and hydrophilic parts of lipid molecules should be responsible for the phenomena.