Foster Jamie S, Lloyd Gareth O
Institute of Chemical Sciences, School of Engineering and Physical Sciences, Heriot-Watt University, Edinburgh, Scotland, EH14 4AS, UK.
Department of Chemistry, School of Natural Sciences, Joseph Banks Laboratories, Lincoln, LN6 7DL, UK.
Faraday Discuss. 2025 Aug 28;260(0):82-93. doi: 10.1039/d5fd00016e.
Autocatalytic and/or self-replicating systems are important aspects of understanding the link between living systems (origins of life) and chemical networks. As a result, many scientists around the world are attempting to better understand these phenomena by producing chemical networks and linking them to self-assembly and pathway complexity (systems chemistry). We present here a superficially autocatalytic, self-replicating system that utilises dynamic imine chemistry coupled with self-assembling supramolecular hydrogelation kinetics driven by a nucleation autocatalytic cycle (autoinduction). The dynamic nature of the imine bond within water allows "error-checking" correction and driving of the imine equilibrium to the starting materials, but when coupled to the self-assembly process it gives rise to one reaction product from a possible thirteen intermediates and/or products (of a mixed four-step reaction). This product represents a thermodynamic minimum within the system's and reaction network's energy landscape. The self-assembly in solution of the replicator results in the formation of supramolecular polymers, which would normally markedly reduce the catalytic efficiency of the system if a template mechanism of autocatalysis is in play. By overcoming the limiting effects of the self-assembly process, it is possible to demonstrate exponential growth in replicator concentration once nucleation has occurred. It is only once the completed imine can undergo non-reversible tautomerisation that the product is prevented from reacting with water. We thus suggest that this sigmoidal kinetic characterisation is not inherent to autocatalysis kinetics (lowering reaction barriers and/or templating), but rather a result of the nucleation-based assembly allowing for intermediates to be prevented from reacting with water in a water-deficient environment (an autoinduction autocatalytic mechanism). Not only does this study provide a basis with which to explore aspects of self-replication connected with self-assembly, but it also explores how nucleation and self-assembly growth can play a crucial role in self-replication. By controlling the kinetics of the autocatalytic chemical reaction at one end of the hierarchical assembly process, we can influence the physical properties of the supramolecular gel at the other end. This may have wide-ranging applications with -formed small molecular gelators where specific mechanical properties (rheology) are desired.
自催化和/或自我复制系统是理解生命系统（生命起源）与化学网络之间联系的重要方面。因此，世界各地的许多科学家都在尝试通过构建化学网络并将其与自组装及途径复杂性（系统化学）联系起来，以更好地理解这些现象。我们在此展示了一个表面上具有自催化作用的自我复制系统，该系统利用动态亚胺化学，结合由成核自催化循环（自动诱导）驱动的自组装超分子水凝胶化动力学。水相中动态的亚胺键性质允许进行“错误检查”校正，并将亚胺平衡驱动至起始原料，但当与自组装过程相结合时，它从可能的十三种中间体和/或产物（混合四步反应的产物）中产生一种反应产物。该产物代表了系统和反应网络能量景观中的热力学最小值。复制子在溶液中的自组装导致超分子聚合物的形成，如果自催化的模板机制起作用，这通常会显著降低系统的催化效率。通过克服自组装过程的限制效应，一旦发生成核，就有可能证明复制子浓度呈指数增长。只有当完整的亚胺能够进行不可逆的互变异构时，产物才会被阻止与水反应。因此，我们认为这种S形动力学特征并非自催化动力学（降低反应壁垒和/或模板作用）所固有，而是基于成核的组装使得中间体在缺水环境中不与水反应的结果（一种自动诱导自催化机制）。这项研究不仅为探索与自组装相关的自我复制方面提供了基础，还探讨了成核和自组装生长如何在自我复制中发挥关键作用。通过控制分级组装过程一端的自催化化学反应动力学，我们可以影响另一端超分子凝胶的物理性质。这对于需要特定机械性能（流变学）的小分子凝胶剂可能具有广泛的应用。
