BRITE Pivot: An Integrated Theory of Continuum and Statistical Mechanics of Active Soft Matter

生物膜是将细胞及其内部细胞器与环境分离的界面。这些膜不可避免地在细胞对机械刺激的反应、通过电化学信号传递信息或交换营养等过程中起着至关重要的作用。迄今为止，大多数研究完全集中在将生物膜视为“被动”膜，其仅由于分子的热振动而表现出波动。然而，越来越多的共识是，膜实际上是“活性”的，这是指它们利用来自外部来源的能量来执行特定功能的能力。这个促进工程变革和公平进步的研究思路（BRITE）枢轴奖支持了解活性膜力学的基础研究，并深入了解它们在关键生物现象中的作用。据设想，这一奋进将铺平道路，以更好地了解，控制，也许模仿生物技术和医疗保健应用的活性生物物质。该研究还将培养研究生在固体力学，流体力学，统计力学和生物物理学交叉的多学科领域。它将丰富PI机构的课程，其中超过50%的学生被归类为属于代表性不足的群体。本研究的目的是建立一个严格的框架，连续介质力学的活性膜，通过整合它与非平衡统计力学。几十年来，连续介质力学领域已经提供了显着的见解被动膜利用工具，从平衡统计力学假设膜处于热平衡。然而，主动力使膜脱离平衡。此外，主动波动的建模需要对嵌入在耗散能量的流体中的膜进行动态分析。这些因素使得传统的平衡统计力学无法模拟活性膜。本研究旨在发展一种新的综合理论来解释活性膜的力学。具体来说，PI将集中在生物学中普遍存在的三种现象- 1）活性膜之间的熵相互作用; 2）囊泡尺寸分布中活性波动的作用，以及3）活性膜中电场的弛豫。该理论框架将为通过理论和计算方法对更复杂的生物现象进行建模开辟道路，并为设计受控实验以了解活性软物质提供路线。该奖项反映了NSF的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Biological membranes are interfaces that separate cells and their internal organelles from their environment. These membranes inevitably play a crucial role in processes such as response of cells to mechanical stimuli, transmission of messages through electrochemical signals, or exchange of nutrients. To date, most studies have focused entirely on treating biological membranes as "passive" membranes that exhibit fluctuations due to thermal vibrations of molecules only. However, there is growing consensus that membranes are actually "active", which refers to their ability to harness energy from an extrinsic source to execute specific functions. This Boosting Research Ideas for Transformative and Equitable Advances in Engineering (BRITE) Pivot award supports fundamental research in understanding the mechanics of active membranes and furnishing insights into their role in critical biological phenomena. It is envisioned that this endeavor will pave the way to better understand, control, and perhaps mimic active biological matter for biotechnology and healthcare applications. The research will also train graduate students in a multidisciplinary area at the intersection of solid mechanics, fluid mechanics, statistical mechanics, and biophysics. It will enrich the curriculum at the PI's institution where over 50 percent of the student body is classified as belonging to underrepresented groups. The objective of this research is to establish a rigorous framework of continuum mechanics for active membranes by integrating it with non-equilibrium statistical mechanics. For decades, the field of continuum mechanics has provided remarkable insights into passive membranes by utilizing tools from equilibrium statistical mechanics which assumes the membranes to be in thermal equilibrium. However, active forces drive a membrane away from equilibrium. Furthermore, modeling of active fluctuations requires dynamic analysis of membranes embedded in a fluid that dissipates energy. These factors render conventional equilibrium statistical mechanics incapable of modeling active membranes. This research seeks to develop a new integrated theory to explain the mechanics of active membranes. Specifically, the PI will focus on three phenomena that are ubiquitous in biology – 1) entropic interactions between active membranes; 2) role of active fluctuations in vesicle size distribution, and 3) relaxation of electric fields in active membranes. The theoretical framework developed here will open avenues for the modeling of more complex biological phenomena by way of theory and computational methods and provide routes for designing controlled experiments to understand active soft matter.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.