Biological cells have long been of interest to researchers due to their capacity to actively control their shape. Accordingly, there is significant interest in generating simplified synthetic protocells that can alter their shape based on an externally or internally generated stimulus. To date, most progress has been made towards controlling the global shape of a protocell, whereas less is known about generating a local shape change. Here, we seek to better understand the possible mechanisms for producing local morphological changes in a popular protocell system, the block copolymer vesicle. Accordingly, we have combined Dissipative Particle Dynamics (DPD) and the Split Reactive Brownian Dynamics algorithm (SRBD) to produce a simulation tool that is capable of modeling the dynamics of self-assembled polymer structures as they undergo chemical reactions. Using this Reactive DPD or RDPD method, we investigate local morphological change driven by either the microinjection of a stimulus or an enzymatically-produced stimulus. We find that sub-vesicle-scale morphological change can be induced by either a solvent stimulus that swells the vesicle membrane, or by a reactant stimulus that alters the chemistry of the block polymer in the membrane corona. Notably, the latter method results in a more persistent local deformation than the former, which we attribute to the slower diffusion of polymer chains relative to the solvent. We quantify this deformation and show that it can be modulated by altering the interaction parameter of the parts of the polymer chain that are affected by the stimulus.

中文翻译：

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使用反应性耗散粒子动力学来了解聚合物囊泡的局部形状操纵

生物细胞由于能够主动控制其形状而长期以来一直受到研究人员的关注。因此，产生可基于外部或内部产生的刺激改变其形状的简化的合成原始细胞引起了极大的兴趣。迄今为止，在控制原始细胞的整体形状方面已经取得了大多数进展，而对于产生局部形状变化知之甚少。在这里，我们试图更好地了解在流行的原生细胞系统（嵌段共聚物囊泡）中产生局部形态变化的可能机制。因此，我们将耗散粒子动力学（DPD）和分裂反应布朗动力学（SRBD）结合起来，产生了一种能够对自组装聚合物结构进行化学反应动力学建模的仿真工具。使用这种反应性DPD或RDPD方法，我们研究了由显微注射刺激物或酶促刺激物驱动的局部形态变化。我们发现，可以通过溶胀囊泡膜的溶剂刺激或通过改变膜电晕中嵌段聚合物化学反应的反应物刺激来诱导亚囊泡规模的形态变化。值得注意的是，后一种方法比前一种方法导致更持久的局部变形，这归因于聚合物链相对于溶剂的扩散较慢。