Tarun O B, Okur H I, Rangamani P, Roke S
Laboratory for fundamental BioPhotonics (LBP), Institute of Bioengineering (IBI), and Institute of Materials Science (IMX), School of Engineering (STI), and Lausanne Centre for Ultrafast Science (LACUS), École Polytechnique Fédérale de Lausanne (EPFL), CH-1015, Lausanne, Switzerland.
Department of Chemistry and National Nanotechnology Research Center (UNAM), Bilkent University, 06800, Ankara, Turkey.
Commun Chem. 2020 Feb 7;3(1):17. doi: 10.1038/s42004-020-0263-8.
Cell membranes are composed of a hydrated lipid bilayer that is molecularly complex and diverse, and the link between molecular hydration structure and membrane macroscopic properties is not well understood, due to a lack of technology that can probe and relate molecular level hydration information to micro- and macroscopic properties. Here, we demonstrate a direct link between lipid hydration structure and macroscopic dynamic curvature fluctuations. Using high-throughput wide-field second harmonic (SH) microscopy, we observe the formation of transient domains of ordered water at the interface of freestanding lipid membranes. These domains are induced by the binding of divalent ions and their structure is ion specific. Using nonlinear optical theory, we convert the spatiotemporal SH intensity into maps of membrane potential, surface charge density, and binding free energy. Using an electromechanical theory of membrane bending, we show that transient electric field gradients across the membrane induce spatiotemporal membrane curvature fluctuations.
细胞膜由一个水合脂质双层组成，其分子结构复杂多样，由于缺乏能够探测分子水平水合信息并将其与微观和宏观性质相关联的技术，分子水合结构与膜宏观性质之间的联系尚未得到很好的理解。在这里，我们展示了脂质水合结构与宏观动态曲率波动之间的直接联系。使用高通量宽场二次谐波（SH）显微镜，我们观察到在独立脂质膜界面处有序水的瞬态域的形成。这些域是由二价离子的结合诱导的，其结构具有离子特异性。使用非线性光学理论，我们将时空SH强度转换为膜电位、表面电荷密度和结合自由能的图谱。使用膜弯曲的机电理论，我们表明跨膜的瞬态电场梯度会引起时空膜曲率波动。
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