This U.S.-Bulgaria research project between Dr. Janos H. Fendler of Syracuse University and Dr. Alexander G. Petrov of the Laboratory of Liquid Crystals and Molecular Electronics of Georgi Nadjakov University, Sofia, will examine flexoelectricity in bilayer lipid membranes. The Bulgarian researchers have found that periodic bending of a bilayer lipid membrane (BLM) results in microvolt-range transmembrane potential. The Bulgarians have a theoretical rationalization of the phenomenon and have examined it by electrical measurements which included the direct determination of Uf and indirect determination of c. The Americans have used optical interferometry to determine ultrasmall, hydrostatic-pressure-induced movements of BLMs. In this proposal, the researchers propose to: (1) use real-time stroboscopic interferometric measurements to determine directly c in the periodically bent BLMs; (2) determine simultaneously electrical and optical flexoelectric coefficients of BLMs, to test theories of flexoelectricity; (3) investigate a variety of structurally different BLMs; (4) study converse flexoelectric effect (transmembrane voltage-induced membrane curvature) with interferometric holography and optical interferometry; (5) establish a correspondence between the direct flexoelectric effect (curvature-generated membrane polarization) and the converse one on the same BLM preparation; (6) investigate changes of the flexoelectric response of a photosensitive BLM under illumination to reveal a new phenomenon, photoflexoelectricity; and (7) attempt to observe photoflexoelectric phenomena by applying repetitive laser pulses to a pigmented BLM. This project in biophysics fulfills the program objective of advancing scientific knowledge by enabling leading experts in the United States and Eastern Europe to combine complementary talents and pool resources in areas of strong mutual interest and competence.
