Müssig Stephan, Wolf Andreas, Kämäräinen Tero, Mandel Karl
Department of Chemistry and Pharmacy, Professorship for Inorganic Chemistry, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Egerlandstraße 1, 91058 Erlangen, Germany.
Department of Chemistry and Pharmacy, Section Materials Chemistry, Chair of Particle-Based Materials Chemistry, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Egerlandstraße 1, 91058 Erlangen, Germany.
Acc Mater Res. 2025 May 23;6(7):842-852. doi: 10.1021/accountsmr.5c00027. eCollection 2025 Jul 25.
The ability to gather information about materials and products, such as their origin, physicochemical properties or history of experienced environmental stimuli, is valuable for quality control, predictive maintenance, delivery tracking, recycling, and more. Integrating additives capable of recording and storing information into materials offers a flexible approach to create "materials intelligence". Common strategies utilize luminescent markers or DNA sequences that enable object identification and environmental impact monitoring. In contrast to optical methods limited to surface-level analysis, magnetic fields penetrate materials, enabling nondestructive readout even from the inside of opaque or multicomponent objects. While magnetic particle technologies have traditionally been used for biosensing and imaging with highly sensitive instruments like magnetic resonance imaging, these methods are unsuitable for quick, on-site analysis of macroscopic objects. During the past decade, magnetic particle spectroscopy (MPS) has emerged as a faster and more accessible characterization technique. MPS measures the magnetic response of particles in ambient conditions under alternating fields, offering high temporal resolution (∼1-10 s) and more geometric freedom than other magnetometry techniques. Magnetic nanoparticles are a widely studied material class that have been synthesized and optimized, e.g., for various MPS-based application scenarios and to obtain fundamental understanding of magnetic particle systems. Supraparticles (SPs) represent the next structural hierarchy level, as they are composed of one or multiple types of (magnetic) nanoparticles in a defined particulate structure. By ingenious control of structure and composition of such SPs, we have shown that various kinds of information can be obtained from them upon readout with MPS. In this Account, we present SP design concepts facilitating to obtain information about environmental stimuli (e.g., temperature, moisture, UV light, chemical gases) based on irreversible spectral magnetic signal changes upon readout with MPS. Initially, the state of the art on nanoparticles, which provide information by stimulus-induced agglomeration, is summarized. Subsequently, SPs consisting of multiple different nanoparticle types and their capabilities to obtain information on environmental stimuli are considered. Specifically, the advantages of using one or more signal transducing magnetic nanoparticle types used in conjunction with one or more nonmagnetic secondary materials susceptible to the desired environmental stimuli (sensitizer) are discussed. Finally, our latest findings on pronounced large-scale SP structure formation (millimeter-scale) through strongly interacting SPs and their implications on the integration of SPs in macroscopic objects of interest are described. Each of the three structural hierarchy levels, namely nanoparticles, SPs, and the macroscopic object of interest, represents an opportunity on the material level to fine-tune magnetic interactions. However, since the magnetic interactions across these three structural hierarchy levels are interdependent, meaning changes at the nanoparticle level influence the interactions of SPs at the macroscopic level, their control and interpretation in MPS remain challenging and prone to misinterpretation. The application of magnetic SPs as information-providing additives for predictive maintenance, material reuse, recycling, and industrial digitization requires a thorough understanding of all three hierarchical levels. Only then can suitable materials and processes be developed, turning challenges into opportunities for transforming passive matter into perceptual, information-providing systems through the integration of magnetic SPs.
收集有关材料和产品的信息,例如其来源、物理化学性质或经历的环境刺激历史,对于质量控制、预测性维护、交付跟踪、回收利用等具有重要价值。将能够记录和存储信息的添加剂整合到材料中,为创造“材料智能”提供了一种灵活的方法。常见策略利用发光标记或DNA序列来实现物体识别和环境影响监测。与限于表面分析的光学方法不同,磁场能够穿透材料,即使对于不透明或多组分物体的内部也能进行无损读出。虽然磁性粒子技术传统上用于通过磁共振成像等高灵敏度仪器进行生物传感和成像,但这些方法不适用于对宏观物体进行快速、现场分析。在过去十年中,磁性粒子光谱学(MPS)已成为一种更快且更易于使用的表征技术。MPS在交变磁场下测量环境条件下粒子的磁响应,与其他磁力测量技术相比,具有高时间分辨率(约1 - 10秒)和更大的几何自由度。磁性纳米粒子是一类经过广泛研究的材料,已针对各种基于MPS的应用场景进行了合成和优化,并用于深入了解磁性粒子系统。超粒子(SPs)代表了下一个结构层次水平,因为它们由一种或多种类型的(磁性)纳米粒子以确定的颗粒结构组成。通过巧妙控制此类SPs的结构和组成,我们已经表明,在用MPS读出时可以从它们中获得各种信息。在本综述中,我们介绍了基于用MPS读出时不可逆的光谱磁信号变化来获取有关环境刺激(例如温度、湿度、紫外线、化学气体)信息的SP设计概念。首先,总结了通过刺激诱导团聚提供信息的纳米粒子的现有技术。随后,考虑了由多种不同类型纳米粒子组成的SPs及其获取环境刺激信息的能力。具体讨论了将一种或多种信号转导磁性纳米粒子类型与一种或多种对所需环境刺激敏感的非磁性二次材料(敏化剂)结合使用的优点。最后,描述了我们关于通过强相互作用的SPs形成明显的大规模SP结构(毫米级)的最新发现及其对将SPs整合到感兴趣的宏观物体中的影响。三个结构层次水平中的每一个,即纳米粒子、SPs和感兴趣的宏观物体,都代表了在材料层面微调磁相互作用的机会。然而,由于跨越这三个结构层次水平的磁相互作用是相互依存的,这意味着纳米粒子层面的变化会影响宏观层面SPs的相互作用,因此在MPS中对它们的控制和解释仍然具有挑战性且容易产生误解。将磁性SPs用作预测性维护、材料再利用、回收利用和工业数字化的信息提供添加剂,需要对所有三个层次水平有透彻的了解。只有这样,才能开发出合适的材料和工艺,通过整合磁性SPs将挑战转化为将被动物质转变为感知、信息提供系统的机会。
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