School of Chemical Engineering, Universiti Sains Malaysia, 14300 Nibong Tebal, Penang, Malaysia.
Department of Biochemical Engineering, School of Chemical Engineering and Technology, Frontier Science Center for Synthetic Biology and Key Laboratory of Systems Bioengineering (MOE), Tianjin University, Tianjin 300350, China.
Langmuir. 2023 Apr 11;39(14):4904-4916. doi: 10.1021/acs.langmuir.2c03164. Epub 2023 Mar 29.
The possible magnetophoretic migration of iron oxide nanoparticles through the cellulosic matrix within a single layer of paper is challenging with its underlying mechanism remained unclear. Even with the recent advancements of theoretical understanding on magnetophoresis, mainly driven by cooperative and hydrodynamics phenomena, the contributions of these two mechanisms on possible penetration of magnetic nanoparticles through cellulosic matrix of paper have yet been proven. Here, by using iron oxide nanoparticles (IONPs), both nanospheres and nanorods, we have investigated the migration kinetics of these nanoparticles through grade 4 Whatman filter paper with a particle retention of 20-25 μm. By performing droplet tracking experiments, the real-time stained area growth of the particle droplet on the filter paper, under the influences of a grade N40 NdFeB magnet, were recorded. Our results show that the spatial and temporal expansion of the IONP stain is biased toward the magnet and such an effect is dependent on (i) particle concentration and (ii) particle shape. The kinetics data were first analyzed by treating it as a radial wicking fluid, and later the IONP distribution within the cellulosic matrix was investigated by optical microscopy. The macroscopic flow front velocities of the stained area ranged from 259 μm/s to 16 040 μm/s. Moreover, the microscopic magnetophoretic velocity of nanorod cluster was also successfully measured as ∼214 μm/s. Findings in this work have indirectly revealed the strong influence of cooperative magnetophoresis and the engineering feasibility of paper-based magnetophoretic technology by taking advantage of magnetoshape anisotropy effect of the particles.
单个纸层中纤维素基质内的氧化铁纳米颗粒可能会发生磁泳迁移，但这种迁移的潜在机制尚不清楚。尽管最近在磁泳方面的理论理解取得了进展，主要是由于协同作用和流体力学现象，但这两种机制对磁性纳米颗粒可能穿透纸张纤维素基质的贡献尚未得到证实。在这里，我们使用了氧化铁纳米颗粒（IONP），包括纳米球和纳米棒，研究了这些纳米颗粒通过 4 级沃特曼滤纸（保留粒径为 20-25μm）的迁移动力学。通过进行液滴跟踪实验，记录了在 N40 钕铁硼磁铁的影响下，粒子液滴在滤纸上实时染色区域的生长情况。我们的结果表明，IONP 染色的空间和时间扩展偏向磁铁，这种效应取决于（i）粒子浓度和（ii）粒子形状。首先通过将其处理为径向吸吮流体来分析动力学数据，然后通过光学显微镜研究 IONP 在纤维素基质内的分布。染色区域的宏观流动前沿速度范围为 259μm/s 至 16040μm/s。此外，还成功测量了纳米棒簇的微观磁泳速度约为 214μm/s。这项工作的发现通过利用粒子的磁形状各向异性效应，间接地揭示了协同磁泳的强烈影响以及基于纸张的磁泳技术的工程可行性。
