Fabrication And Applications Of New Supported Lipid Bilayer Membranes

Cells are the basic unit of lives. Almost all the metabolism processes in cells arerelated to biomembranes. However, the separation and purification of membraneproteins usually involve harsh conditions，so artificial lipid membranes are widely usedto study the structure, property and function of biomembranes. Ion-channels inbiomembranes are important ways to exchange substance between cells and theenvironment. Many scientists endeavor in the research of ion channel based on thesupported lipid bilayer membranes. Recently, polyaniline attracted a lot of attention inbiosensors due to its unique properties.In this paper, first we combined polyaniline and supported lipid bilayer membrane,deposited polyaniline on the gold plate using an electrochemical method. The cyclicvoltammatry (CV) curve in sulfuric solution and potassium ferricyanide solutionshowed that the conductivity of polyaniline was fine. Then we prepared lipid bilayermembrane on the polyaniline modified gold substrate, the formation of the lipid bilayermembrane was proved by the elecreochemical impedance spectroscopy (EIS) andfluorescence recovery after photobleaching (FRAP) method. Finally, the ionphore(valinomycins) was embedded in the membrane. Thus the potassium biosensor wasready to use. EIS data showed that the addition of K+leaded to the decrease ofmembrane resistance at the same time the increase of the membrane conductivity. Thispotassium biosensor showed linear response to the K+concentration from1to25mmol/L with good selectivity.The impedance of lipid bilayer membrane formed on the conventional supportedelectrode surface is not high enough to detect ion channel. In this paper, high impedancelipid bilayer membrane system was fabricated. First the electrode area on thetrimethoxyoctadecylsilane(ODS) modified ITO surface was manipulated. The minimumradius we can control was30μm. Then the high impedance system was fabricated onthe ODS modified ITO and bare ITO substrate, respectively. The formation of bilayerlipid membrane was confirmed by the comparision of drop shape before and after theaddition of egg PC to hexane, CV and EIS method. The EIS fitted data showed that thelipid bilayer membrane resistsnce on the ODS modified ITO elecreode was21.6MΩ.The lipid bilayer membrane resistsnce on the bare ITO substrate can reach to80MΩ.This value is higher than other lipid membrane system formed on the same substrate. Inthis lipid membrane system, there is no current leak, which leads to the high impedancesystem.