S-layer supported functional lipid membranes

Research project P 14419 S-layer supported functional lipid membranes Dietmar PUM 08.05.2000 Target of the proposed project is to use a monolayer of crystalline bacterial-cell-surface-layer (S-layer) proteins as intermediate and stabilizing layer for the development of solid supported functional lipid membranes. S-protein monolayers shall act as ultrathin water carrying layers between substrate and lipid layer providing an ionic reservoir space and natural environment for functional lipid membranes. We would like to follow two main strategies which differ in the type of supporting substrates used: (i) Polymer membranes with open cell foam like structures or radiation track membranes (pore size > 0.2m) and (ii) silicon based substrates with metal electrodes or an integrated Ion Sensitive Field Effect Transistor (ISFET) architecture. After direct assembly or deposition of an S-layer on the supporting substrates and the deposition of a phospholipid bilayer transmembrane functions (e.g. ion channels) will be reconstituted using standard procedures (e.g. reconstitution or vesicle fusion). Further, we expect that the assembly of an additional S-layer on the exposed surface of the functional lipid membrane will lead to an increase in mechanical and chemical long term robustness of the layered supramolecular architecture. Electrophysical parameters (e.g. membrane thickness, capacitance, lifetime, break down voltage) and the characteristics of functional lipid membranes will be determined by electrochemical measurements, surface plasmon resonance

Target of this project was the use a monolayer of crystalline bacterial-cell-surface-layer (S-layer) proteins as intermediate and stabilizing layer for the development of solid supported functional lipid membranes. S-layer protein monolayers act as ultrathin water carrying layers between substrate and lipid layer providing an ionic reservoir space and natural environment for functional lipid membranes. Two main strategies which differ in the type of supporting substrates were followed: (i) Polymer membranes with open cell foam like structures and (ii) silicon wafers with evaporated metal electrodes. After reassembly of S-layer proteins on the supporting substrates and the deposition of a phospholipid bilayer or tetraether lipid monolayers transmembrane functions had been reconstituted. Electrophysical parameters (e.g. membrane thickness, capacitance, lifetime, break down voltage) and the characteristics of the attached functional lipid membranes were determined by electrochemical measurements, surface plasmon resonance, and impedance spectroscopy. The present results have demonstrated that S-layer supported lipid membranes preserve the in-vivo functionalities of membrane-based proteins. Thus, S-layer supported lipid membranes have a significant application potential in biosensing, nanobiotechnology and biomimetics. Results had been published in international high impact journals.