Single Particle and Polymer Tracking in Two-Dimensional Energy Landscapes

生物细胞膜是蛋白质和脂类(即纳米级物体)扩散传输的复合膜，可以教我们如何控制从纳米到微米尺度的扩散二维传输。在非均一类脂膜中，从简单的空间排斥到复杂的粘性或静电相互作用，各种各样的相互作用都可以局部影响探针粒子的运动。在这里，我们重点研究刚性区域的空间排斥和吸引的偶极-偶极/电荷相互作用对局域扩散的影响。我们以前的结果表明，Langmuir单分子膜、支撑双层膜和巨泡中的磁区结构的变化可以在一维和二维扩散以及布朗和次扩散之间切换。首先，我们将跟踪点状探针(乳胶球、量子点、耦合到脂类的量子点)在由区域大小和形状调制的变化的能量景观中的运动。我们不仅将学习如何在一维和二维以及布朗和亚扩散传输之间有控制地切换，而且我们还将在这些复杂的电影中对复杂的能量景观进行分类。其次，我们分析了聚合物在这样的能量环境中的扩散行为。聚合物作为点扩散链(DNA、肌动蛋白细丝)的连接链具有内部自由度。首先知道单点扩散器的作用，可以更好地理解它们的行为。对于许多生物过程，自然界更喜欢二维扩散而不是基于定向分子马达的运输。了解膜中的扩散是如何被调节的，将有助于理解为什么进化经常选择这条路线。

Membranes of biological cells exemplify a complex film for diffusive transport of proteins and lipids (i.e. nano-sized objects) and can teach us how to control diffusive two-dimensional transport from the nano- to micro-scale. In inhomogeneous lipid membranes a wide variety of interactions from simple steric repulsion to complex viscous or electrostatic interactions can locally influence the motion of a probe particle. Here, we focus on the impact of the interplay between steric repulsion of rigid domains and attractive dipole-dipole/charge interactions on local diffusion. Our previous results indicate that changes in the domain structure in Langmuir monolayers, supported bilayers, and giant vesicles can switch between one- and two-dimensional diffusion as well as Brownian and subdiffusion. First, we will track the motions of point-like probes (latex spheres, quantum dots, quantum dots coupled to lipids) in changing energy landscapes modulated by domain-size and shape. We will not only learn how to switch in a controlled fashion between one- and two dimensional as well as Brownian and subdiffusive transport, but we will also catalogue the complex energy landscapes in these complex films. Secondly, we analyze the diffusive behavior of polymers in such an energy landscape. Polymers as connected chain of point diffusors (DNA, actin filaments) have internal degrees of freedom. Their behavior can be better understood knowing first what a single point diffusor does. For many biological processes nature prefers two-dimensional diffusive over directed molecular motorbased transport. Understanding how diffusion in membranes can be modulated will help to comprehend why evolution has frequendy chosen this route.