Wolf Andreas, Heinlein Markus, Kent Noah, Müssig Stephan, Mandel Karl
Department of Chemistry and Pharmacy, Professorship for Inorganic Chemistry, Friedrich-Alexander-University Erlangen-Nürnberg (FAU), Egerlandstraße 1, 91058, Erlangen, Germany.
Fraunhofer Institute for Silicate Research ISC, Neunerplatz 2, 97082, Wuerzburg, Germany.
Small. 2025 Apr;21(13):e2412311. doi: 10.1002/smll.202412311. Epub 2025 Feb 21.
Magnetic supraparticles (SPs) can be employed as micron-sized particulate additives in arbitrary objects to serve as ID-tag or recorder of environmental triggers. Combined with magnetic particle spectroscopy (MPS), which enables read-out of the magnetic information in ambient conditions within seconds, magnetic SPs represent a powerful approach to equip materials with information. The encoded information relies on magnetic interactions within the SPs (intra-SP interactions) of chosen nanoparticles (NPs). However, possible magnetic interactions between SPs (inter-SP interactions), that might alter the MPS signal as well, have been neglected so far. Herein, it is elucidated that significant inter-SP interactions exist and that they can be tailored via adjustments in the SP structure, i.e., by defined adjustments of their intra-interaction as revealed by 3D-MuMax simulations and experiments in viscous fluids. Superparamagnetic iron oxide nanoparticle-based SP powders with strong inter-SP interactions exhibit significantly different MPS signals compared to their state after being incorporated into a matrix. Powders with weak inter-SP interactions (achieved by integration of non-magnetic SiO nanoparticles) show almost no signal change before and after incorporation. Both extremes of inter-SP interactions can be beneficial for various application scenarios and can be tailored on the nano-scale due to the interdependency of intra- and inter-SP interactions.
磁性超粒子（SPs）可作为微米级颗粒添加剂用于任意物体中，充当环境触发因素的身份标签或记录器。结合能够在数秒内读取环境条件下磁信息的磁颗粒光谱法（MPS），磁性超粒子是一种为材料赋予信息的强大方法。编码信息依赖于所选纳米颗粒（NPs）的超粒子内部（粒子内相互作用）的磁相互作用。然而，超粒子之间可能存在的磁相互作用（粒子间相互作用）也可能改变MPS信号，到目前为止一直被忽视。在此，我们阐明了显著的粒子间相互作用是存在的，并且可以通过调整超粒子结构来进行调控，即通过3D-MuMax模拟和粘性流体实验所揭示的对其内部相互作用进行特定调整。与掺入基质后的状态相比，具有强粒子间相互作用的基于超顺磁性氧化铁纳米颗粒的超粒子粉末表现出显著不同的MPS信号。具有弱粒子间相互作用的粉末（通过掺入非磁性SiO纳米颗粒实现）在掺入前后几乎没有信号变化。粒子间相互作用的这两种极端情况对各种应用场景都可能有益，并且由于粒子内和粒子间相互作用的相互依存性，可以在纳米尺度上进行调控。
