School of Mechanics and Engineering Science, Zhengzhou University, Zhengzhou 450001, China.
Graduate School of Science and Technology, Shinshu University, Nagano 390-8621, Japan.
ACS Appl Mater Interfaces. 2021 Mar 10;13(9):10667-10673. doi: 10.1021/acsami.0c17890. Epub 2021 Mar 1.
In this study, we demonstrated that arrays of cell clusters can be fabricated by self-assembled hexagonal superparamagnetic cone structures. When a strong out-of-plane magnetic field was applied to the ferrofluid on a glass substrate, it will induce the magnetic poles on the upper/lower surfaces of the continuous ferrofluid to increase the magnetostatic energy. The ferrofluid will then experience hydrodynamic instability and be split into small droplets with cone structures because of the compromising surface tension energy and magnetostatic energy to minimize the system's total energy. Furthermore, the ferrofluid cones were orderly self-assembled into hexagonal arrays to reach the lowest energy state. After dehydration of these liquid cones to form solid cones, polydimethylsiloxane was cast to fix the arrangement of hexagonal superparamagnetic cone structures and prevent the leakage of magnetic nanoparticles. The U-343 human neuronal glioblastoma cells were labeled with magnetic nanoparticles through endocytosis in co-culture with a ferrofluid. The number of magnetic nanoparticles internalized was (4.2 ± 0.84) × 10 per cell by the cell magnetophoresis analysis. These magnetically labeled cells were attracted and captured by hexagonal superparamagnetic cone structures to form cell cluster arrays. As a function of the solid cone size, the number of cells captured by each hexagonal superparamagnetic cone structure was increased from 48 to 126 under a 2000 G out-of-plane magnetic field. The local magnetic field gradient of the hexagonal superparamagnetic cone was 117.0-140.9 G/mm from the cell magnetophoresis. When an external magnetic field was applied, we observed that the number of protrusions of the cell edge decreased from the fluorescence images. It showed that the local magnetic field gradient caused by the hexagonal superparamagnetic cones restricted the cell growth and migration.
在这项研究中，我们展示了可以通过自组装的六方超顺磁锥结构来制造细胞簇阵列。当强的面外磁场施加到玻璃基底上的铁磁流体时，它将增加连续铁磁流体上下表面上的磁极，以增加静磁能。铁磁流体随后会经历流体动力学不稳定性，并由于表面张力能和静磁能的妥协而分裂成具有锥结构的小液滴，以最小化系统的总能量。此外，铁磁流体锥有序地自组装成六方阵列以达到最低能量状态。在这些液体锥脱水形成固体锥之后，聚二甲基硅氧烷被浇铸以固定六方超顺磁锥结构的排列并防止磁性纳米颗粒的泄漏。通过与铁磁流体共培养，U-343 人神经胶质母细胞瘤细胞通过胞吞作用被磁性纳米颗粒标记。通过细胞磁泳分析，每个细胞内化的磁性纳米颗粒数为(4.2±0.84)×10。这些磁性标记的细胞被六方超顺磁锥结构吸引并捕获，形成细胞簇阵列。作为固体锥尺寸的函数，在 2000 G 的面外磁场下，每个六方超顺磁锥结构捕获的细胞数从 48 个增加到 126 个。从细胞磁泳中得到的六方超顺磁锥的局部磁场梯度为 117.0-140.9 G/mm。当施加外部磁场时，我们从荧光图像中观察到细胞边缘的突起数量减少。这表明六方超顺磁锥产生的局部磁场梯度限制了细胞的生长和迁移。
