arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 2007.01927cond-mat.softcond-mat.mtrl-scicond-mat.stat-mechphysics.bio-phq-bio.BM
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自限制组装的平衡机制

Equilibrium mechanisms of self-limiting assembly

Michael F. Hagan, Gregory M. Grason

AI总结:

本综述探讨了自限制组装的平衡机制,通过统计力学框架解析相同亚基如何通过非共价作用选择有限尺寸,并分类介绍了自闭合与开放边界两大组装系统及其物理机制与局限性。

摘要:

自组装是合成和生物系统中普遍存在的过程,广义上定义为多个亚基(如大分子、颗粒)自发组织成有序的多单元结构。绝大多数平衡组装过程会产生两种状态:一种由分散的解离亚基组成,另一种是无限制尺寸的体凝聚态。本综述聚焦于更专门的“自限制组装”类别,该类别描述了产生有限尺寸结构的平衡组装过程。这些系统提出了一个通用且基本的问题:涉及相同亚基之间非共价相互作用的热力学过程如何“测量”并选择组装结构的尺寸?在本综述中,我们首先介绍组装热力学的基本统计力学框架,并以此强调确保平衡组装在有限维度终止的关键物理要素。然后,我们介绍自限制组装系统的实例,并根据两大类别在该框架内对其进行分类:自闭合组装和开放边界组装。这些包括生物学和合成软物质中的著名案例——两亲性分子的胶束化以及锥形亚基的壳/管形成——以及较少为人所知的组装类别,如短程吸引/长程排斥系统和几何受挫组装。对于每一种自限制机制,我们描述了选择平衡组装尺寸的物理机制,以及有限尺寸选择的潜在局限性。最后,我们讨论了有限尺寸组装的替代机制,并将其与平衡单物种组装中的自限制所能实现的尺寸控制进行对比。

英文摘要:

Self-assembly is a ubiquitous process in synthetic and biological systems, broadly defined as the spontaneous organization of multiple subunits (e.g. macromolecules, particles) into ordered multi-unit structures. The vast majority of equilibrium assembly processes give rise to two states: one consisting of dispersed disassociated subunits, and the other, a bulk-condensed state of unlimited size. This review focuses on the more specialized class of {\it self-limiting assembly}, which describes equilibrium assembly processes resulting in finite-size structures. These systems pose a generic and basic question, how do thermodynamic processes involving non-covalent interactions between identical subunits ``measure'' and select the size of assembled structures? In this review, we begin with an introduction to the basic statistical mechanical framework for assembly thermodynamics, and use this to highlight the key physical ingredients that ensure equilibrium assembly will terminate at finite dimensions. Then, we introduce examples of self-limiting assembly systems, and classify them within this framework based on two broad categories: {\it self-closing assemblies} and {\it open-boundary assemblies}. These include well-known cases in biology and synthetic soft matter -- micellization of amphiphiles and shell/tubule formation of tapered subunits -- as well as less widely known classes of assemblies, such as short-range attractive/long-range repulsive systems and geometrically-frustrated assemblies. For each of these self-limiting mechanisms, we describe the physical mechanisms that select equilibrium assembly size, as well as potential limitations of finite-size selection. Finally, we discuss alternative mechanisms for finite-size assemblies, and draw contrasts with the size-control that these can achieve relative to self-limitation in equilibrium, single-species assemblies.

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