论文标题

由固有二分法驱动的主动响应胶体

Active responsive colloids driven by intrinsic dichotomous noise

论文作者

Göth, Nils, Baul, Upayan, Dzubiella, Joachim

论文摘要

我们研究了固有噪声对响应胶体(RCS)的结构和动力学的影响,该胶体(RCS)会积极改变其大小和相互作用。除粒子翻译外,胶体大小在我们的RC模型中明确解决了作为内部自由度(DOF)。 RCS之间的Hertzian对势会导致颗粒的排斥和收缩,从而导致系统对自我拥挤的明显响应能力。为了使胶体活跃起来,它们的大小是由二分法噪声在内部驱动的,在生长状态和缩小状态之间以预定义的速率随机切换(“呼吸”),这是由于最近在合成活性胶体上的实验所激发的。该二分法主动响应胶体(D-arc)模型的多分散性可以通过噪声的参数来调节。利用随机计算机模拟,我们研究了对D-Arcs的密集悬浮液的空间分布,放松时间和自扩散的影响。我们发现“内置”固有噪声对系统行为的实质性影响,特别是从单峰到双峰大小分布的过渡,以增加胶体密度的增加以及固有的噪声修饰扩散转化动力学。我们得出的结论是,控制大分子或细胞的内部DOF的噪声是活跃胶体材料的强大工具,可以使系统的集体结构自主变化和动力学对宏观特性对外部扰动的适应。

We study the influence of intrinsic noise on the structure and dynamics of responsive colloids (RCs) which actively change their size and mutual interactions. The colloidal size is explicitly resolved in our RC model as an internal degree of freedom (DOF) in addition to the particle translation. A Hertzian pair potential between the RCs leads to repulsion and shrinking of the particles, resulting in an explicit responsiveness of the system to self-crowding. To render the colloids active, their size is internally driven by a dichotomous noise, randomly switching ('breathing') between growing and shrinking states with a predefined rate, as motivated by recent experiments on synthetic active colloids. The polydispersity of this dichotomous active responsive colloid (D-ARC) model can be tuned by the parameters of the noise. Utilizing stochastic computer simulations, we study crowding effects on the spatial distributions, relaxation times, and self-diffusion of dense suspensions of the D-ARCs. We find a substantial influence of the 'built-in' intrinsic noise on the system's behavior, in particular, transitions from unimodal to bimodal size distributions for an increasing colloid density as well as intrinsic noise-modified diffusive translational dynamics. We conclude that controlling the noise of internal DOFs of a macromolecule or cell is a powerful tool for active colloidal materials to enable autonomous changes in the system's collective structure and dynamics towards the adaption of macroscopic properties to external perturbations.

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