The human iron storage protein ferritin represents an appealing template to realise a semisynthetic magnetic nanoparticle (MNP) for spatial manipulation or inductive heating applications on a nanoscale. Ferritin consists of a protein cage of well-defined size (12 nm), which is genetically modifiable, biocompatible, and into which a magnetic core is synthesised. Here, we probe the magnetic response and hence the MNP’s suitability for (bio-)nanotechnological or nanomedical applications, when the core is doped with 7 % cobalt or 7 % zinc, in comparison to the undoped iron oxide MNP. The samples exhibit almost identical core and hydrodynamic sizes, along with their tunable magnetic core characteristics as verified by structural and magnetic characterisation. Cobalt doping significantly increased the MNP’s anisotropy and hence the heating power in comparison to the other magnetic cores with potential application as a mild heat mediator. Spatial magnetic manipulation was tested with MNPs inside droplets, the cell cytoplasm, or the cell nucleus, where the MNP surface conjugation with mEGFP and poly(ethylene glycol) gave rise to excellent intracellular stability and traceability within the complex biological environment. A magnetic stimulus (smaller than fN forces) results in the quick and reversible redistribution of the MNPs. The obtained data suggest that semisynthetic ferritin MNPs are highly versatile nanoagents and promising candidates for theranostic or (bio-)nanotechnological applications.

中文翻译：

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具有高磁各向异性的半合成铁蛋白纳米粒子，用于空间磁操纵和感应加热

人类铁储存蛋白铁蛋白是实现半合成磁性纳米粒子（MNP）的一个有吸引力的模板，用于纳米尺度的空间操纵或感应加热应用。铁蛋白由尺寸明确 (12 nm) 的蛋白质笼组成，该蛋白质笼可进行基因修饰、具有生物相容性，并在其中合成了磁芯。在这里，我们探讨了当核心掺杂 7% 钴或 7% 锌时，与未掺杂的氧化铁 MNP 相比，MNP 的磁响应以及 MNP 对于（生物）纳米技术或纳米医学应用的适用性。这些样品表现出几乎相同的磁芯和流体动力学尺寸，以及通过结构和磁特性验证的可调磁芯特性。与其他磁芯相比，钴掺杂显着增加了 MNP 的各向异性，从而提高了加热功率，具有作为温和热介质的潜在应用。使用液滴、细胞质或细胞核内的 MNP 测试了空间磁操纵，其中 MNP 表面与 mEGFP 和聚乙二醇的缀合在复杂的生物环境中产生了优异的细胞内稳定性和可追溯性。磁刺激（小于 fN 力）会导致 MNP 快速且可逆地重新分布。获得的数据表明，半合成铁蛋白 MNP 是高度通用的纳米制剂，并且是治疗诊断或（生物）纳米技术应用的有希望的候选者。