Department of Physics, Kyushu University, Motooka 744, Fukuoka 819-0395, Japan.
Department of Applied Physics, Aalto University School of Science, Puumiehenkuja 2, Espoo, 02150, Finland.
Soft Matter. 2023 Jul 5;19(26):5016-5028. doi: 10.1039/d3sm00071k.
Topological defects in nematically aligned cell populations play a critical role in modulating collective motion, ranging from microbial colonies to epithelial tissues. Despite the potential of manipulating such topological defects to control diverse self-organized structures and collective dynamics, controlling the position of defects in active matter remains a challenging area of research. In this study, we investigated the geometry-guided control of defect positioning and alignment in a nematic cell population by imposing spatial constraints consisting of two or three overlapping circular boundaries. The confined cell population exhibited a paired and ordered distribution of half-integer topological defects that remained stable even when the size of the spatial constraint was altered using geometric parameters. These defects direct the inward flow of cells, induced by the curved boundary shape, towards the geometric center of the confined space. This inward flow contributes to an increase in a local cell density, and furthermore the geometry-induced nematic order provides mechanical stimulation to confined cells, as indicated by the elongated cell nucleus. Our geometry-based approach sets the foundation for controlling defect pairing and provides insights into the interplay among geometry, topology, and collective dynamics.
各向异性排列的细胞群体中的拓扑缺陷在调节从微生物菌落到上皮组织等各种集体运动中起着关键作用。尽管可以操纵这些拓扑缺陷来控制不同的自组织结构和集体动力学，但控制活性物质中的缺陷位置仍然是一个具有挑战性的研究领域。在这项研究中，我们通过施加由两个或三个重叠的圆形边界组成的空间约束，研究了各向异性细胞群体中缺陷定位和排列的几何控制。在受限的细胞群体中，观察到半整数拓扑缺陷的配对和有序分布，即使使用几何参数改变空间约束的大小，这些缺陷仍然保持稳定。这些缺陷将细胞的向内流动引导到受限空间的几何中心，这种向内流动导致局部细胞密度增加，此外，几何诱导的各向异性有序为受限细胞提供机械刺激，这可以从拉长的细胞核中看出来。我们的基于几何的方法为控制缺陷配对奠定了基础，并深入了解了几何形状、拓扑和集体动力学之间的相互作用。
