Driven, directed or crowded: dynamics of soft matter near and far from equilibrium

驱动、定向或拥挤：软物质接近和远离平衡的动力学

• 批准号: RGPIN-2019-04970
• 负责人: Yethiraj, Anand
• 金额: $ 5.34万
• 依托单位: Memorial University of Newfoundland
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2021
• 资助国家: 加拿大
• 起止时间: 2021-01-01 至 2022-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=737983
• 关键词: Driven; directed; crowded; dynamics; soft

A unifying framework for understanding non-equilibrium physics does not exist. In this research program we will study dynamics in three classes of experimental model systems that are out of equilibrium which address complementary aspects of non-equilibrium behavior: energy injection and dissipation, modification of interparticle interactions and role of environment. The first objective is to create dynamically responsive materials. First, we wish to make micron-scale, monodisperse, asymmetric Brownian designer droplets in large quantities. Making complex colloidal structures for phase behavior studies is challenging. Our hypothesis is that driving systems far from equilibrium, in this case via electrohydrodynamic drop breakup, will enable us to create smaller structures. Second, self-driven motion in living cells (termed as activity) is inherently nanoscale; however, all colloidal analogs of active matter have been micron-scale and 2-dimensional. We will devise a nanoscale light-activated motor, using bacteriorhodopsin (a light-activated proton pump) embedded in a lipid bicelle, and examine, using experiments in a non-living model system, the role of activity in directing organization in living systems. A second objective is to study kinetics of colloidal cluster formation. Competing colloidal interactions can result in structures of intermediate order: e.g., the combination of long-range electrostatic repulsions and short-range depletion forces gives clusters, gels, and glassy states. We will examine, for the first time, the combination of depletion and anisotropic dipolar forces. With this, we hope to address the long-standing question: does the dipolar gas-liquid transition exist? We will then switch dipolar interactions on and off to study kinetics of cluster formation quantitatively. Parallel to this, we will examine peculiar clustering phenomena that are observed but not understood. We will test our hypothesis that this clustering is a consequence of charge regulation, which can give rise to spontaneous charge asymmetries in a homogeneous colloidal system. A third objective is to understand the effect of the crowded environment on molecular dynamics and conformations in living cells: this is referred to as macromolecular crowding. While several qualitative insights have emerged as to its nature, a true quantitative understanding is not achieved even in simple model systems. Using synthetic polymers both as crowder and probe molecule, we will examine the role of charge, polydispersity, and hydrodynamic interactions using a diverse set of experimental tools. We will compare synthetic polymer probe molecules with real proteins, as well as synthetic crowders with real bacterial cell material. Control of colloidal self-assembly has led to fundamental advances and to new materials. The vision is that extending the study of self-assembly to systems far from equilibrium, where intuition often fails, will lead to new fundamental insights.

不存在理解非平衡物理的统一框架。在该研究计划中，我们将研究三类实验模型系统的动态，这些模型系统不平衡，这些系统无法衡量非平衡行为的互补方面：能量注入和耗散，颗粒间相互作用的修改以及环境的作用。 第一个目标是创建动态响应材料。首先，我们希望大量制作微米尺度，单分散，不对称的布朗设计师液滴。为相行为研究制作复杂的胶体结构是具有挑战性的。我们的假设是，在这种情况下，通过电水动力学分解，驱动系统远非平衡，将使我们能够创建较小的结构。其次，活细胞中的自我驱动运动（称为活性）本质上是纳米级。但是，活性物质的所有胶体类似物都是微米级和二维的。我们将使用嵌入脂质bicelle中的细菌紫红素（一种光活化的质子泵）设计纳米级的光激活电动机，并使用非生存模型系统中的实验来检查活动在实现生命系统中的活动中的作用。第二个目标是研究胶体簇形成的动力学。竞争性胶体相互作用会导致中间顺序的结构：例如，远程静电排斥力和短距离耗竭力的组合可为簇，凝胶和玻璃状态提供。我们将首次研究耗竭和各向异性偶极力的组合。这样，我们希望解决一个长期存在的问题：偶性气体液体过渡是否存在？然后，我们将打开和关闭偶极相互作用，以定量研究簇形成的动力学。与此相关的是，我们将研究观察到但尚未理解的特殊聚类现象。我们将测试我们的假设，即这种聚类是电荷调节的结果，这可能会导致同质胶体系统中自发的电荷不对称。第三个目标是了解拥挤的环境对活细胞中分子动力学和构象的影响：这被称为大分子拥挤。尽管已经出现了几种定性见解，但即使在简单的模型系统中，也无法实现真正​​的定量理解。我们将使用合成聚合物作为Crowder和探针分子，我们将使用一组不同的实验工具来检查电荷，多分散性和流体动力相互作用的作用。我们将将合成聚合物探针分子与真实蛋白质以及具有真实细菌细胞材料的合成人群进行比较。控制胶体自组装已导致基本进步和新材料。愿景是，将自组装的研究扩展到远离直觉失败的均衡的系统将导致新的基本见解。