Liquid Crystalline Orientational Excitations in Biological Membranes

生物膜被认为是生命形成和增殖的关键。跨膜的物质交换负责其平衡操作以及动作电位的传播。了解这些过程的基本机制对于我们与许多疾病的斗争至关重要。与此同时，构成生物膜的分子的取向顺序已经与液晶（LC）进行了比较。然而，没有进一步详细比较LC中发生的各种激发模式的机制与生物组织（如生物膜）中发生的类似过程。我们认为，液晶材料的各向异性性质在生物膜中应该有非常重要的类比。也就是说，与髓鞘的分子“堆叠”平面（类似于近晶LC）的情况相比，“简单”分子双层膜（类似于近晶LC）中离子的各向异性扩散的临界差异是可能使用我们对近晶和近晶LC的物理学知识以更好地理解各种生物膜中发生的过程的一个很好的例子。此外，我们最近发现存在的定向分子微扰与长程传播距离。这为我们更好地理解髓鞘、朗维尔结和离子通道在动作电位传播过程中的触发机制提供了希望。一旦我们更好地理解这些机制，我们计划使用光活化的两亲性无毒偶氮苯，以控制这种分子系统（膜）中的取向顺序，从而控制材料（离子等）的机制。交换他们。事实上，我们已经开始了其中的一些实验，我们用大肠杆菌获得的第一个结果非常令人鼓舞。我们已经证明，光可以用来控制它们的游泳速度，这是它们毒力的关键因素。我们认为这种控制是通过偶氮苯分子的光致异构化作用使离子通道不稳定而实现的。在本研究中，我们将首先使用液晶和人工脂质双层进行基础研究。然后，我们将研究这些材料中的电荷迁移率在偶氮苯分子的存在下，在各种激发制度允许控制这些分子的反式和顺式种群之间的平衡。然后我们将研究具有双层膜的细菌。最后，我们将开发光遗传学工具，允许在大脑富含髓鞘的区域注射和选择性光激活偶氮苯分子，试图局部控制大脑激活水平。我们希望这些研究将有助于开发光电工具和技术（过程），用于主动控制具有众多医学应用的生物组织。

The biological membrane is considered as key for the formation and proliferation of life. The material exchange across this membrane is responsible for its equilibrium operation as well as during the action potential's propagation. The understanding of underlying mechanisms of these processes is paramount for our fight against many diseases. In the same time, the orientational order of molecules, composing the biological membrane, has already been compared with liquid crystals (LC). However, there was no further detailed comparison of the mechanisms of various excitation modes, taking place in LCs, with respect to similar processes taking place in the biological tissue, such as the biological membrane. We think that the anisotropic properties of LC materials should have very important analogies in biological membranes. Namely, the critical difference of anisotropic diffusion of ions in "simple" molecular double layer membranes (similar to nematic LCs) compared with the case of molecular "stacking" planes of myelin sheaths (similar to smectic LCs) is a good example of the possible use of our knowledge of the physics of nematic and smectic LCs to better understand the processes taking place in various biological membranes. In addition, we have recently discovered the existence of orientational molecular perturbations with long range propagation distances. This gives us the hope to better understand the role of myelin sheaths, the nodes of Ranvier and the triggering mechanism of ionic channels during the action potential's propagation. Once we understand these mechanisms better, we are planning to use photo activated amphiphilic non-toxic azobenzenes, to control the orientational order in such molecular systems (membranes) and thus the mechanisms of material (ionic, etc.) exchange across them. In fact, we have already started some of these experiments and our very first results, obtained with the Ecoli bacteria, are very encouraging. We have shown that light can be used to control their swimming speed which is a key factor for their virulence. We think that this control is obtained by the destabilization of ionic channel via the photoisomerization of azobenzene molecules. In the proposed research, we shall first use LCs and artificial lipid bilayers for our basic studies. Then, we shall study the charge mobility in these materials in the presence of azobenzene molecules during various excitation regimes allowing the control of the equilibrium between Trans and Cis populations of these molecules. Then we shall work with bacteria with bilayer membranes. Finally, we shall develop optogenetic tools allowing the injection and the selective photo activation of azobenzene molecules in myelin rich regions of the brain, trying to control locally the brain activation level. We hope that these studies will help to develop optoelectronic tools and techniques (processes) for the active control of the biological tissue with numerous medical applications.