US-Bulgaria Research on Flexoelectricity in Bilayer Lipid Membranes

这项由锡拉丘兹大学的Janos H.Fendler博士和索非亚Georgi Nadjakov大学液晶和分子电子学实验室的Alexander G.Petrov博士共同开展的美国-保加利亚研究项目，将检测双层类脂膜中的挠曲电性。保加利亚的研究人员发现，双层类脂膜(BLM)的周期性弯曲会导致微伏范围的跨膜电位。保加利亚人对这种现象有理论上的合理性，并通过电学测量对其进行了检验，其中包括直接测定UF和间接测定c。美国人使用光学干涉测量法来确定超小型，静水压力作用下BLM的运动。在这个方案中，研究人员建议：(1)使用实时频闪干涉测量来直接确定周期性弯曲的BLM中的c；(2)同时测定BLM的电学和光学柔电系数，以验证BLM的弯曲电学理论：(3)研究各种结构不同的BLM；(4)用干涉全息术和光学干涉计量学研究逆曲电效应(跨膜电压感生膜曲率)；(5)在相同的BLM制备中，建立正向挠曲电效应(曲率产生的膜极化)和反向挠曲电效应之间的对应关系；(6)研究了光敏薄膜在光照下的挠曲电响应的变化，揭示了一种新的现象--光挠曲电性；以及(7)尝试通过向着色的BLM施加重复的激光脉冲来观察光折变现象。这个生物物理学项目通过使美国和东欧的顶尖专家能够将互补的人才结合在一起，并在相互感兴趣和能力很强的领域汇集资源，从而实现了促进科学知识的计划目标。

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.