STABILIZED BILAYER-LIPID MEMBRANES FOR FLOW-THROUGH EXPERIMENTS

This work reports a technique for the stabilization of solventless bil ayer lipid membranes (BLMs), and the use of stabilized BLMs as flow de tectors. Microporous filters composed of glass fibers, polytetrafluoro ethylene (PTFE) and polycarbonate (nominal pore sizes from 1 to 5 mu m ) can serve as interfaces that separate two solution compartments. The micropores in the filter media can act as supports for formation and stabilization of BLMs. One of the solution compartments is used to cas t lipid films on the filters, while a carrier electrolyte solution con currently hows through the opposing compartment. Optimization of the h ow cell design, and the chemical composition and methods for preparati on of stabilized BLMs, are described. Lipid membranes composed of mixt ures of phosphatidyl choline and phosphatidic acid could respond rapid ly to pH alterations of the carrier electrolyte solution. Signals woul d reproducibly appear within a few seconds following the injection of an electrolyte of different pH than the carrier. Signals took the form of a single ion current transient with magnitude of tens of picoamper es (pA) and a duration of seconds. The mechanism of signal generation is explored by differential scanning calorimetry. The results show tha t a phase transition within a lipid membrane can be triggered by pH al terations of the electrolyte solution. Stabilized BLMs which provide a rtificial ion gating events hold prospects for chemical sensing of pro cess streams.