Ma Mingrou, Zhu Hui, Ling Jing, Gong Suqin, Zhang Yin, Xia Yunsheng, Tang Zhiyong
Key Laboratory of Functional Molecular Solids, Ministry of Education, College of Chemistry and Materials Science, Anhui Normal University, Wuhu 241000, China.
CAS Key Laboratory of Nanosystem and Hierarchical Fabrication, CAS Center for Excellence in Nanoscience, National Center for Nanoscience and Technology, Beijing 100190, China.
ACS Nano. 2020 Apr 28;14(4):4036-4044. doi: 10.1021/acsnano.9b08570. Epub 2020 Mar 25.
The exploration of magnetic resonance imaging (MRI) agents possessing excellent performances and high biosafety is of great importance for both fundamental science research and biomedical applications. In this study, we present that monodisperse FeO supraparticles (SPs) can act as -weighted MRI agents, which not only possess a distinct off-on MRI switch in the tumor microenvironment but also are readily excreted from living bodies due to its quasi-amorphous structure and hierarchical topology design. First, the FeO SPs have a surface-to-volume ratio obviously smaller than that of their building blocks by means of self-assembly processes, which, on the one hand, causes a rather low relaxivity (0.19 mM s) and, on the other hand, can effectively prevent their aggregation after intravenous injection. Second, the FeO SPs have a dramatic disassembly/degradation-induced active -weighted signal readout (more than 6 times the value enhancement and about 20 times the / ratio decrease) in the tumor microenvironment, resulting in a high signal-to-noise ratio for imaging performances. Therefore, they possess excellent imaging capacity, even with a tumor size as small as 5 mm. Third, the disassembled/decomposed behaviors of the FeO SPs facilitate their timely clearance/excretion from living bodies. In particular, they exhibit distinct renal clearance behavior without any kidney damage with the right dosage. Fourth, the favorable biodegradability of the as-prepared FeO SPs can further relieve the concerns about the unclear biological effects, particularly on nanomaterials, in general.
探索具有优异性能和高生物安全性的磁共振成像（MRI）造影剂对于基础科学研究和生物医学应用都非常重要。在本研究中，我们提出单分散的FeO超粒子（SPs）可作为T2加权MRI造影剂，其不仅在肿瘤微环境中具有独特的开-关MRI切换特性，而且由于其准无定形结构和分级拓扑设计，易于从活体中排出。首先，通过自组装过程，FeO SPs的表面体积比明显小于其构建单元，这一方面导致相当低的横向弛豫率（0.19 mM-1 s-1），另一方面可有效防止其在静脉注射后聚集。其次，FeO SPs在肿瘤微环境中具有显著的分解/降解诱导的活性T2加权信号读出（T2值增强超过6倍，T1/T2比值降低约20倍），从而实现高信噪比的成像性能。因此，即使肿瘤尺寸小至5 mm，它们也具有优异的T2成像能力。第三，FeO SPs的分解/降解行为有助于它们从活体中及时清除/排出。特别是，在合适的剂量下，它们表现出明显的肾清除行为且不会对肾脏造成任何损伤。第四，所制备的FeO SPs良好的生物降解性可进一步缓解人们对一般纳米材料尚不清楚的生物学效应的担忧。
