Thermodynamics of Growing Active and Living Matter

活性物质和生命物质生长的热力学

• 批准号: EP/W027194/1
• 负责人: Elsen Tjhung
• 金额: $ 128.66万
• 依托单位: The Open University
• 依托单位国家: 英国
• 项目类别: Fellowship
• 财政年份: 2023
• 资助国家: 英国
• 起止时间: 2023 至 无数据
• 项目状态: 未结题
• 来源: https://gtr.ukri.org/projects?ref=EP%2FW027194%2F1
• 关键词: Thermodynamics; Growing; Active; Living; Matter

When we learnt classical thermodynamics from undergraduate physics/chemistry, we often assumed a large number of particles ~10^23, equilibrium, and quasi-static process. In this very restrictive limit, thermodynamic quantities such as heat dissipation Q, can be computed using the textbook formula Q= T\Delta S, where S is the configurational entropy. However, in real lives, most physical processes are neither quasi-static nor equilibrium. Furthermore, in many biological systems, the number of degrees of freedom is also much less than 10^23, and in this regime, thermal fluctuations become important. Thus, thermodynamic quantities such as heat, work and entropy need to be redefined properly (Stochastic Thermodynamics). The first aim of this research is to extend the theory of stochastic thermodynamics to include birth and death process, e.g., cellular division and apoptosis in living tissues and growing bacterial colonies.One important application of stochastic thermodynamics is the prospects of biological machines, which are powered by the swimming motility in some bacteria, or even cellular division and apoptosis in our bodies. For instance, it has been well known experimentally and theoretically that if we place an asymmetric cog inside a bath full of swimming bacteria, the cog can somehow rotate persistently in one direction. The bacteria themselves, in the absence of the cog, swim in a completely random direction; and yet the interaction between the bacteria and the asymmetric cog can break time reversal symmetry to create a macroscopic unidirectional current. Although this phenomenon has been well established in motile active matter (such as swimming bacteria), very little is known about non-motile growing active matter (such as cell division and apoptosis in living tissues and bacterial colonies).In this research, I will explore cellular division and apoptosis as a new route to the development of biological machines. This is important because unlike cell motility, cell division and apoptosis are universal properties of living matter. My design principles for such machines will pave the way for future possible applications in healthcare technologies and tissue engineering, such controlling the growth of tissue using non-uniform scaffolding.Finally, I will investigate the thermodynamic properties of these machines. In particular, I will quantify the informatic entropy production of the birth and death process inside biological tissues and bacterial colonies, i.e., particles dividing into two and disappearing elsewhere. To achieve this, I will extend the current theory of stochastic thermodynamics to include birth and death process and stochastic processes that are much faster than quasi-static (i.e., quenching). This information will be crucial in understanding how time reversal symmetry breaking at small scales (i.e., cell cycle) can be translated into large scales (i.e., collective motion in tissues and bacterial colonies). Apart from obvious applications to active/living matter, my research will also help to transform the science of thermodynamics, such as understanding the energy flow in a quenching process and/or processes close to a critical point, where thermal fluctuations are important.

当我们从本科物理/化学中学习经典热力学时，我们经常假设大量的粒子~10^23，平衡和准静态过程。在这个非常严格的限制中，热动力学量，如热耗散Q，可以使用教科书公式Q= T\Delta S计算，其中S是构型熵。然而，在真实的生活中，大多数物理过程既不是准静态的，也不是平衡的。此外，在许多生物系统中，自由度的数量也远小于10^23，在这种情况下，热涨落变得很重要。因此，热、功和熵等热力学量需要重新定义（随机热力学）。本研究的第一个目的是将随机热力学理论扩展到包括生灭过程，例如，随机热力学的一个重要应用是生物机器的前景，它是由某些细菌的游动运动提供动力的，甚至是我们体内的细胞分裂和凋亡。例如，在实验和理论上，我们都知道，如果我们把一个不对称的齿轮放在一个充满游泳细菌的浴缸里，齿轮可以以某种方式持续地朝一个方向旋转。在没有齿轮的情况下，细菌本身以完全随机的方向游动;然而细菌和不对称齿轮之间的相互作用可以打破时间反演对称性，从而产生宏观单向电流。虽然这种现象在运动的活性物质（如游动的细菌）中已经得到了很好的证实，但对于非运动的生长活性物质（如活组织和细菌菌落中的细胞分裂和凋亡）却知之甚少。在本研究中，我将探索细胞分裂和凋亡作为生物机器发展的新途径。这一点很重要，因为与细胞运动不同，细胞分裂和凋亡是生命物质的普遍特性。我的设计原则，这种机器将铺平道路，为未来可能的应用在医疗技术和组织工程，如控制组织的生长使用非均匀的scaffolding.最后，我将调查这些机器的热力学性质。特别是，我将量化生物组织和细菌菌落内部出生和死亡过程的信息熵产生，即，粒子一分为二，消失在别处。为了实现这一点，我将扩展当前的随机热力学理论，以包括出生和死亡过程以及比准静态快得多的随机过程（即，淬火）。这些信息对于理解小尺度下的时间反演对称性破缺（即，细胞周期）可以转化为大尺度（即，组织和细菌菌落中的集体运动）。除了明显的应用到活性/生命物质，我的研究也将有助于改变热力学的科学，如了解淬火过程中的能量流和/或接近临界点的过程，其中热波动是重要的。